From 96b1761ed163309e5757e5d0e84cdb658cc8aae3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Sun, 26 Apr 2020 18:30:41 +0200
Subject: [PATCH 01/26] mv ocaml src

---
 {ocaml => src}/.gitignore                | 0
 {ocaml => src}/Makefile                  | 0
 {ocaml => src}/bench.ml                  | 0
 {ocaml => src}/dune                      | 0
 {ocaml => src}/dune-project              | 0
 {ocaml => src}/make-random/bench.ml      | 0
 {ocaml => src}/make-random/dune          | 0
 {ocaml => src}/make-random/makeRandom.ml | 0
 {ocaml => src}/make-random/test.ml       | 0
 {ocaml => src}/splitmix/dune             | 0
 {ocaml => src}/splitmix/sm64.ml          | 0
 {ocaml => src}/tests/dune                | 0
 {ocaml => src}/tests/ocamlrandom.ml      | 0
 {ocaml => src}/tests/splitmix.ml         | 0
 {ocaml => src}/tests/xoshiro.ml          | 0
 {ocaml => src}/xoshiro/dune              | 0
 {ocaml => src}/xoshiro/x256pp.ml         | 0
 {ocaml => src}/xoshiro/x256pp_c/x256pp.c | 0
 {ocaml => src}/xoshiro/x256pp_c/x256pp.h | 0
 19 files changed, 0 insertions(+), 0 deletions(-)
 rename {ocaml => src}/.gitignore (100%)
 rename {ocaml => src}/Makefile (100%)
 rename {ocaml => src}/bench.ml (100%)
 rename {ocaml => src}/dune (100%)
 rename {ocaml => src}/dune-project (100%)
 rename {ocaml => src}/make-random/bench.ml (100%)
 rename {ocaml => src}/make-random/dune (100%)
 rename {ocaml => src}/make-random/makeRandom.ml (100%)
 rename {ocaml => src}/make-random/test.ml (100%)
 rename {ocaml => src}/splitmix/dune (100%)
 rename {ocaml => src}/splitmix/sm64.ml (100%)
 rename {ocaml => src}/tests/dune (100%)
 rename {ocaml => src}/tests/ocamlrandom.ml (100%)
 rename {ocaml => src}/tests/splitmix.ml (100%)
 rename {ocaml => src}/tests/xoshiro.ml (100%)
 rename {ocaml => src}/xoshiro/dune (100%)
 rename {ocaml => src}/xoshiro/x256pp.ml (100%)
 rename {ocaml => src}/xoshiro/x256pp_c/x256pp.c (100%)
 rename {ocaml => src}/xoshiro/x256pp_c/x256pp.h (100%)

diff --git a/ocaml/.gitignore b/src/.gitignore
similarity index 100%
rename from ocaml/.gitignore
rename to src/.gitignore
diff --git a/ocaml/Makefile b/src/Makefile
similarity index 100%
rename from ocaml/Makefile
rename to src/Makefile
diff --git a/ocaml/bench.ml b/src/bench.ml
similarity index 100%
rename from ocaml/bench.ml
rename to src/bench.ml
diff --git a/ocaml/dune b/src/dune
similarity index 100%
rename from ocaml/dune
rename to src/dune
diff --git a/ocaml/dune-project b/src/dune-project
similarity index 100%
rename from ocaml/dune-project
rename to src/dune-project
diff --git a/ocaml/make-random/bench.ml b/src/make-random/bench.ml
similarity index 100%
rename from ocaml/make-random/bench.ml
rename to src/make-random/bench.ml
diff --git a/ocaml/make-random/dune b/src/make-random/dune
similarity index 100%
rename from ocaml/make-random/dune
rename to src/make-random/dune
diff --git a/ocaml/make-random/makeRandom.ml b/src/make-random/makeRandom.ml
similarity index 100%
rename from ocaml/make-random/makeRandom.ml
rename to src/make-random/makeRandom.ml
diff --git a/ocaml/make-random/test.ml b/src/make-random/test.ml
similarity index 100%
rename from ocaml/make-random/test.ml
rename to src/make-random/test.ml
diff --git a/ocaml/splitmix/dune b/src/splitmix/dune
similarity index 100%
rename from ocaml/splitmix/dune
rename to src/splitmix/dune
diff --git a/ocaml/splitmix/sm64.ml b/src/splitmix/sm64.ml
similarity index 100%
rename from ocaml/splitmix/sm64.ml
rename to src/splitmix/sm64.ml
diff --git a/ocaml/tests/dune b/src/tests/dune
similarity index 100%
rename from ocaml/tests/dune
rename to src/tests/dune
diff --git a/ocaml/tests/ocamlrandom.ml b/src/tests/ocamlrandom.ml
similarity index 100%
rename from ocaml/tests/ocamlrandom.ml
rename to src/tests/ocamlrandom.ml
diff --git a/ocaml/tests/splitmix.ml b/src/tests/splitmix.ml
similarity index 100%
rename from ocaml/tests/splitmix.ml
rename to src/tests/splitmix.ml
diff --git a/ocaml/tests/xoshiro.ml b/src/tests/xoshiro.ml
similarity index 100%
rename from ocaml/tests/xoshiro.ml
rename to src/tests/xoshiro.ml
diff --git a/ocaml/xoshiro/dune b/src/xoshiro/dune
similarity index 100%
rename from ocaml/xoshiro/dune
rename to src/xoshiro/dune
diff --git a/ocaml/xoshiro/x256pp.ml b/src/xoshiro/x256pp.ml
similarity index 100%
rename from ocaml/xoshiro/x256pp.ml
rename to src/xoshiro/x256pp.ml
diff --git a/ocaml/xoshiro/x256pp_c/x256pp.c b/src/xoshiro/x256pp_c/x256pp.c
similarity index 100%
rename from ocaml/xoshiro/x256pp_c/x256pp.c
rename to src/xoshiro/x256pp_c/x256pp.c
diff --git a/ocaml/xoshiro/x256pp_c/x256pp.h b/src/xoshiro/x256pp_c/x256pp.h
similarity index 100%
rename from ocaml/xoshiro/x256pp_c/x256pp.h
rename to src/xoshiro/x256pp_c/x256pp.h

From 4aa7f55647ef12e37bb24476b1f3641a3310cae3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Sun, 26 Apr 2020 19:05:30 +0200
Subject: [PATCH 02/26] Sm64 C reference implementation as an ocaml module

---
 c/Makefile                |  3 ---
 c/splitmix64.c            | 26 --------------------------
 c/splitmix64.h            |  3 ---
 c/testsplitmix.c          | 16 ----------------
 compare.sh                | 17 -----------------
 src/splitmix/dune         |  1 +
 src/splitmix/reference.c  | 13 +++++++++++++
 src/splitmix/reference.h  | 10 ++++++++++
 src/splitmix/reference.ml |  2 ++
 src/splitmix/stubs.c      | 23 +++++++++++++++++++++++
 10 files changed, 49 insertions(+), 65 deletions(-)
 delete mode 100644 c/splitmix64.c
 delete mode 100644 c/splitmix64.h
 delete mode 100644 c/testsplitmix.c
 delete mode 100755 compare.sh
 create mode 100644 src/splitmix/reference.c
 create mode 100644 src/splitmix/reference.h
 create mode 100644 src/splitmix/reference.ml
 create mode 100644 src/splitmix/stubs.c

diff --git a/c/Makefile b/c/Makefile
index 691c63f..ef136ec 100644
--- a/c/Makefile
+++ b/c/Makefile
@@ -1,8 +1,5 @@
 all: testxoshiro testocamlrandom testsplitmix
 
-testsplitmix: testsplitmix.c splitmix64.c splitmix64.h
-	cc -o $@ $< splitmix64.c
-
 testxoshiro: testxoshiro.c xoshiro256pp.c xoshiro256pp.h
 	cc -o $@ $< xoshiro256pp.c
 
diff --git a/c/splitmix64.c b/c/splitmix64.c
deleted file mode 100644
index 6dcbad8..0000000
--- a/c/splitmix64.c
+++ /dev/null
@@ -1,26 +0,0 @@
-/*  Written in 2015 by Sebastiano Vigna (vigna@acm.org)
-
-To the extent possible under law, the author has dedicated all copyright
-and related and neighboring rights to this software to the public domain
-worldwide. This software is distributed without any warranty.
-
-See <http://creativecommons.org/publicdomain/zero/1.0/>. */
-
-#include <stdint.h>
-
-/* This is a fixed-increment version of Java 8's SplittableRandom generator
-   See http://dx.doi.org/10.1145/2714064.2660195 and
-   http://docs.oracle.com/javase/8/docs/api/java/util/SplittableRandom.html
-
-   It is a very fast generator passing BigCrush, and it can be useful if
-   for some reason you absolutely want 64 bits of state. */
-
-static uint64_t x = 0xdead42beef37ca7a; /* The state can be seeded with any value. */
-
-uint64_t next() {
-	uint64_t z = (x += 0x9e3779b97f4a7c15);
-	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
-	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
-	return z ^ (z >> 31);
-}
-
diff --git a/c/splitmix64.h b/c/splitmix64.h
deleted file mode 100644
index 9b48294..0000000
--- a/c/splitmix64.h
+++ /dev/null
@@ -1,3 +0,0 @@
-#include <stdint.h>
-
-uint64_t next();
diff --git a/c/testsplitmix.c b/c/testsplitmix.c
deleted file mode 100644
index 2aa6e34..0000000
--- a/c/testsplitmix.c
+++ /dev/null
@@ -1,16 +0,0 @@
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include "splitmix64.h"
-
-
-int main(int argc, char* argv[]) {
-  int n = 10;
-  if (argc == 2) n = atoi(argv[1]);
-
-  for (int i = 0; i < n; i++)
-    printf("%016lx\n", next());
-
-  return 0;
-}
-
diff --git a/compare.sh b/compare.sh
deleted file mode 100755
index 4904341..0000000
--- a/compare.sh
+++ /dev/null
@@ -1,17 +0,0 @@
-#!/bin/sh
-
-set -e
-
-compare () {
-  echo "Comparing '$1' and '$2'..."
-  tmp="$(mktemp)"
-  "$1" 1000 > "$tmp"
-  test -z "$("$2" 1000 | diff "$tmp" -)"
-  rm -f "$tmp"
-}
-
-make -C ocaml tests
-make -C c all
-
-compare ocaml/_build/default/tests/splitmix.exe c/testsplitmix
-echo OK!
diff --git a/src/splitmix/dune b/src/splitmix/dune
index 72ad3ae..1852a11 100644
--- a/src/splitmix/dune
+++ b/src/splitmix/dune
@@ -1,3 +1,4 @@
 (library
  (name splitmix)
+ (foreign_stubs (language c) (names reference stubs))
  (libraries makeRandom))
diff --git a/src/splitmix/reference.c b/src/splitmix/reference.c
new file mode 100644
index 0000000..d653006
--- /dev/null
+++ b/src/splitmix/reference.c
@@ -0,0 +1,13 @@
+// Reference: http://prng.di.unimi.it/splitmix64.c
+
+#include <stdint.h>
+
+uint64_t sm64_state; /* The state can be seeded with any value. */
+
+uint64_t sm64_next() {
+	uint64_t z = (sm64_state += 0x9e3779b97f4a7c15);
+	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
+	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
+	return z ^ (z >> 31);
+}
+
diff --git a/src/splitmix/reference.h b/src/splitmix/reference.h
new file mode 100644
index 0000000..aef2394
--- /dev/null
+++ b/src/splitmix/reference.h
@@ -0,0 +1,10 @@
+#ifndef SPLITMIX64_H
+#define SPLITMIX64_H
+
+#include <stdint.h>
+
+uint64_t sm64_state;
+uint64_t sm64_next();
+
+#endif
+
diff --git a/src/splitmix/reference.ml b/src/splitmix/reference.ml
new file mode 100644
index 0000000..79543d1
--- /dev/null
+++ b/src/splitmix/reference.ml
@@ -0,0 +1,2 @@
+external seed: int64 -> unit = "caml_sm64_seed"
+external next: unit -> int64 = "caml_sm64_next"
diff --git a/src/splitmix/stubs.c b/src/splitmix/stubs.c
new file mode 100644
index 0000000..daf31ed
--- /dev/null
+++ b/src/splitmix/stubs.c
@@ -0,0 +1,23 @@
+#define CAML_NAME_SPACE
+#include <caml/mlvalues.h>
+#include <caml/memory.h>
+#include <caml/alloc.h>
+#include <stdint.h>
+#include "reference.h"
+
+CAMLprim value caml_sm64_seed(value seed) {
+  CAMLparam1(seed);
+  int64_t x = Int64_val(seed);
+  // reinterpret x as an unsigned integer
+  sm64_state = *(uint64_t*)(&x);
+  CAMLreturn(Val_unit);
+}
+
+CAMLprim value caml_sm64_next(value unit) {
+  CAMLparam1(unit);
+  uint64_t x = sm64_next();
+  // reinterpret x as a signed integer
+  value res = caml_copy_int64(*(int64_t*)(&x));
+  CAMLreturn(res);
+}
+

From 485e691de246dabe67e2058264ac44cb876254e9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Mon, 27 Apr 2020 00:39:19 +0200
Subject: [PATCH 03/26] Test Sm64 against reference implementation

---
 src/splitmix/dune     |  8 +++++++-
 src/splitmix/tests.ml | 18 ++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 src/splitmix/tests.ml

diff --git a/src/splitmix/dune b/src/splitmix/dune
index 1852a11..62a2772 100644
--- a/src/splitmix/dune
+++ b/src/splitmix/dune
@@ -1,4 +1,10 @@
 (library
  (name splitmix)
  (foreign_stubs (language c) (names reference stubs))
- (libraries makeRandom))
+ (libraries makeRandom)
+ (modules :standard \ Tests))
+
+(test
+ (name tests)
+ (modules Tests)
+ (libraries splitmix))
diff --git a/src/splitmix/tests.ml b/src/splitmix/tests.ml
new file mode 100644
index 0000000..197f7b0
--- /dev/null
+++ b/src/splitmix/tests.ml
@@ -0,0 +1,18 @@
+open Splitmix
+
+let test_compare nb f g =
+  for _ = 1 to nb do
+    assert (f () = g ())
+  done
+
+let () =
+  (* Chosen by fair dice rool. Guaranted to be random. *)
+  (* https://xkcd.com/221/ *)
+  let seed = 0xdd6d0e2e849e51adL in
+  let ocaml_state = ref seed in
+
+  Reference.seed seed;
+  test_compare
+    1_000_000
+    Reference.next
+    (fun () -> Sm64.next ocaml_state)

From 8f44bdde72efa149ba24dc919f8fcf1351ba8bfe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Mon, 27 Apr 2020 23:48:09 +0200
Subject: [PATCH 04/26] xoshiro256++ ref implementation as an OCaml module

---
 c/xoshiro256pp.c                            | 50 ---------------------
 src/xoshiro/dune                            |  2 +-
 src/xoshiro/reference.c                     | 45 +++++++++++++++++++
 c/xoshiro256pp.h => src/xoshiro/reference.h |  4 +-
 src/xoshiro/reference.ml                    |  2 +
 src/xoshiro/stubs.c                         | 23 ++++++++++
 6 files changed, 74 insertions(+), 52 deletions(-)
 delete mode 100644 c/xoshiro256pp.c
 create mode 100644 src/xoshiro/reference.c
 rename c/xoshiro256pp.h => src/xoshiro/reference.h (50%)
 create mode 100644 src/xoshiro/reference.ml
 create mode 100644 src/xoshiro/stubs.c

diff --git a/c/xoshiro256pp.c b/c/xoshiro256pp.c
deleted file mode 100644
index 30685eb..0000000
--- a/c/xoshiro256pp.c
+++ /dev/null
@@ -1,50 +0,0 @@
-/*  Written in 2019 by David Blackman and Sebastiano Vigna (vigna@acm.org)
-
-To the extent possible under law, the author has dedicated all copyright
-and related and neighboring rights to this software to the public domain
-worldwide. This software is distributed without any warranty.
-
-See <http://creativecommons.org/publicdomain/zero/1.0/>. */
-
-#include <stdint.h>
-#include <stdio.h>
-
-/* This is xoshiro256++ 1.0, one of our all-purpose, rock-solid generators.
-   It has excellent (sub-ns) speed, a state (256 bits) that is large
-   enough for any parallel application, and it passes all tests we are
-   aware of.
-
-   For generating just floating-point numbers, xoshiro256+ is even faster.
-
-   The state must be seeded so that it is not everywhere zero. If you have
-   a 64-bit seed, we suggest to seed a splitmix64 generator and use its
-   output to fill s. */
-
-static inline uint64_t rotl(const uint64_t x, int k) {
-	return (x << k) | (x >> (64 - k));
-}
-
-
-static uint64_t s[4] = {
-  0xdeadbeefdeadbeef,
-  0x4242424242424242,
-  0x3737373737373737,
-  0xca7aca7aca7aca7a
-};
-
-uint64_t next(void) {
-	const uint64_t result = rotl(s[0] + s[3], 23) + s[0];
-
-	const uint64_t t = s[1] << 17;
-
-	s[2] ^= s[0];
-	s[3] ^= s[1];
-	s[1] ^= s[2];
-	s[0] ^= s[3];
-
-	s[2] ^= t;
-
-	s[3] = rotl(s[3], 45);
-
-	return result;
-}
diff --git a/src/xoshiro/dune b/src/xoshiro/dune
index baefbf5..2fbfc89 100644
--- a/src/xoshiro/dune
+++ b/src/xoshiro/dune
@@ -2,4 +2,4 @@
 
 (library
  (name xoshiro)
- (foreign_stubs (language c) (names x256pp)))
+ (foreign_stubs (language c) (names x256pp stubs reference)))
diff --git a/src/xoshiro/reference.c b/src/xoshiro/reference.c
new file mode 100644
index 0000000..dc03d63
--- /dev/null
+++ b/src/xoshiro/reference.c
@@ -0,0 +1,45 @@
+// Reference:  http://prng.di.unimi.it/xoshiro256plusplus.c
+
+#include <stdint.h>
+
+static inline uint64_t rotl(const uint64_t x, int k) {
+	return (x << k) | (x >> (64 - k));
+}
+
+uint64_t x256pp_state[4] = {
+  0xd430ebc2f4d9e7b8,
+  0x44815975ddd19d52,
+  0xbb18c2b0b18d0bfe,
+  0x6c0681407295c644
+};
+
+uint64_t x256pp_next(void) {
+	const uint64_t result = rotl(x256pp_state[0] + x256pp_state[3], 23) + x256pp_state[0];
+
+	const uint64_t t = x256pp_state[1] << 17;
+
+	x256pp_state[2] ^= x256pp_state[0];
+	x256pp_state[3] ^= x256pp_state[1];
+	x256pp_state[1] ^= x256pp_state[2];
+	x256pp_state[0] ^= x256pp_state[3];
+
+	x256pp_state[2] ^= t;
+
+	x256pp_state[3] = rotl(x256pp_state[3], 45);
+
+	return result;
+}
+
+static uint64_t splitmix64(uint64_t* s) {
+	uint64_t z = (*s += 0x9e3779b97f4a7c15);
+	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
+	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
+	return z ^ (z >> 31);
+}
+
+void x256pp_seed(uint64_t seed) {
+  uint64_t s = seed;
+  for (int i = 0; i < 4; i++)
+    x256pp_state[i] = splitmix64(&s);
+}
+
diff --git a/c/xoshiro256pp.h b/src/xoshiro/reference.h
similarity index 50%
rename from c/xoshiro256pp.h
rename to src/xoshiro/reference.h
index 4f24453..ec5d146 100644
--- a/c/xoshiro256pp.h
+++ b/src/xoshiro/reference.h
@@ -3,6 +3,8 @@
 
 #include <stdint.h>
 
-uint64_t next();
+uint64_t x256pp_state[4];
+uint64_t x256pp_next();
+void x256pp_seed(uint64_t);
 
 #endif
diff --git a/src/xoshiro/reference.ml b/src/xoshiro/reference.ml
new file mode 100644
index 0000000..ee7ef1e
--- /dev/null
+++ b/src/xoshiro/reference.ml
@@ -0,0 +1,2 @@
+external seed: int64 -> unit = "caml_x256pp_seed"
+external next: unit -> int64 = "caml_x256pp_next"
diff --git a/src/xoshiro/stubs.c b/src/xoshiro/stubs.c
new file mode 100644
index 0000000..518cac6
--- /dev/null
+++ b/src/xoshiro/stubs.c
@@ -0,0 +1,23 @@
+#define CAML_NAME_SPACE
+#include <caml/mlvalues.h>
+#include <caml/memory.h>
+#include <caml/alloc.h>
+#include <stdint.h>
+#include "reference.h"
+
+CAMLprim value caml_x256pp_seed(value seed) {
+  CAMLparam1(seed);
+  int64_t x = Int64_val(seed);
+  // reinterpret x as an unsigned integer
+  x256pp_seed(*(uint64_t*)(&x));
+  CAMLreturn(Val_unit);
+}
+
+CAMLprim value caml_x256pp_next(value unit) {
+  CAMLparam1(unit);
+  uint64_t x = x256pp_next();
+  // reinterpret x as a signed integer
+  value res = caml_copy_int64(*(int64_t*)(&x));
+  CAMLreturn(res);
+}
+

From 95401e28666ea1fcfe6151571cbc9ad574a85a8d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Tue, 28 Apr 2020 00:58:31 +0200
Subject: [PATCH 05/26] Merge x256pp_c/* and stubs.c

---
 src/xoshiro/dune              |  4 +--
 src/xoshiro/stubs.c           | 19 ++++++++++++
 src/xoshiro/x256pp.ml         |  6 ++--
 src/xoshiro/x256pp_c/x256pp.c | 55 -----------------------------------
 src/xoshiro/x256pp_c/x256pp.h | 12 --------
 5 files changed, 23 insertions(+), 73 deletions(-)
 delete mode 100644 src/xoshiro/x256pp_c/x256pp.c
 delete mode 100644 src/xoshiro/x256pp_c/x256pp.h

diff --git a/src/xoshiro/dune b/src/xoshiro/dune
index 2fbfc89..ceca707 100644
--- a/src/xoshiro/dune
+++ b/src/xoshiro/dune
@@ -1,5 +1,3 @@
-(include_subdirs unqualified)
-
 (library
  (name xoshiro)
- (foreign_stubs (language c) (names x256pp stubs reference)))
+ (foreign_stubs (language c) (names stubs reference)))
diff --git a/src/xoshiro/stubs.c b/src/xoshiro/stubs.c
index 518cac6..2c872d3 100644
--- a/src/xoshiro/stubs.c
+++ b/src/xoshiro/stubs.c
@@ -21,3 +21,22 @@ CAMLprim value caml_x256pp_next(value unit) {
   CAMLreturn(res);
 }
 
+CAMLprim value caml_x256pp_bits(value unit) {
+  CAMLparam1(unit);
+  intnat res = x256pp_next() >> 34;
+  CAMLreturn(Val_long(res));
+}
+
+CAMLprim value caml_x256pp_bits62(value unit) {
+  CAMLparam1(unit);
+  long res = x256pp_next() >> 2;
+  CAMLreturn(Val_long(res));
+}
+
+CAMLprim value caml_x256pp_double(value f) {
+  CAMLparam1(f);
+  double res = (x256pp_next() >> 11) * 0x1.0p-53;
+  res *= Double_val(f);
+  CAMLreturn(caml_copy_double(res));
+}
+
diff --git a/src/xoshiro/x256pp.ml b/src/xoshiro/x256pp.ml
index 44a8ed5..cd69cf7 100644
--- a/src/xoshiro/x256pp.ml
+++ b/src/xoshiro/x256pp.ml
@@ -164,7 +164,7 @@ module Int64 = struct
 end
 
 module C = struct
-  external bits: unit -> int = "x256pp_bits"
-  external bits62: unit -> int = "x256pp_bits62"
-  external float: float -> float = "x256pp_double"
+  external bits: unit -> int = "caml_x256pp_bits"
+  external bits62: unit -> int = "caml_x256pp_bits62"
+  external float: float -> float = "caml_x256pp_double"
 end
diff --git a/src/xoshiro/x256pp_c/x256pp.c b/src/xoshiro/x256pp_c/x256pp.c
deleted file mode 100644
index c768a4d..0000000
--- a/src/xoshiro/x256pp_c/x256pp.c
+++ /dev/null
@@ -1,55 +0,0 @@
-#include "x256pp.h"
-#include <stdint.h>
-#include <stdio.h>
-
-static inline uint64_t rotl(const uint64_t x, int k) {
-	return (x << k) | (x >> (64 - k));
-}
-
-static uint64_t s[4] = {
-  0xdeadbeefdeadbeef,
-  0x4242424242424242,
-  0x3737373737373737,
-  0xca7aca7aca7aca7a
-};
-
-static uint64_t next(void) {
-	const uint64_t result = rotl(s[0] + s[3], 23) + s[0];
-
-	const uint64_t t = s[1] << 17;
-
-	s[2] ^= s[0];
-	s[3] ^= s[1];
-	s[1] ^= s[2];
-	s[0] ^= s[3];
-
-	s[2] ^= t;
-
-	s[3] = rotl(s[3], 45);
-
-	return result;
-}
-
-static long int buf = 0;
-static int buf_len = 0;
-static const uint64_t mask30 = (1 << 30) - 1;
-
-CAMLprim value x256pp_bits() {
-  if (buf_len == 0) {
-    buf = next();
-    buf_len = 2;
-  }
-  long int res = buf & mask30;
-  buf_len--;
-  buf = buf >> 32;
-  return Val_long(res);
-}
-
-CAMLprim value x256pp_bits62() {
-  return Val_long(next() >> 2);
-}
-
-CAMLprim value x256pp_double(value f) {
-  double d = (next() >> 11) * 0x1.0p-53 * Double_val(f);
-  return caml_copy_double(d);
-}
diff --git a/src/xoshiro/x256pp_c/x256pp.h b/src/xoshiro/x256pp_c/x256pp.h
deleted file mode 100644
index 77d8b8a..0000000
--- a/src/xoshiro/x256pp_c/x256pp.h
+++ /dev/null
@@ -1,12 +0,0 @@
-#ifndef X256PP_H
-#define X256PP_H 1
-
-#define CAML_NAME_SPACE
-#include <caml/mlvalues.h>
-#include <caml/alloc.h>
-
-CAMLprim value x256pp_bits();
-CAMLprim value x256pp_bits62();
-CAMLprim value x256pp_double(value);
-
-#endif

From 430acce2d480afd5bddb629a3ddde63fb4926445 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Tue, 28 Apr 2020 00:30:02 +0200
Subject: [PATCH 06/26] Test X256pp.Int64 against reference implementation

---
 src/xoshiro/tests/dune         |  3 +++
 src/xoshiro/tests/testInt64.ml | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 src/xoshiro/tests/dune
 create mode 100644 src/xoshiro/tests/testInt64.ml

diff --git a/src/xoshiro/tests/dune b/src/xoshiro/tests/dune
new file mode 100644
index 0000000..76caeda
--- /dev/null
+++ b/src/xoshiro/tests/dune
@@ -0,0 +1,3 @@
+(tests
+ (names testInt64)
+ (libraries splitmix xoshiro))
diff --git a/src/xoshiro/tests/testInt64.ml b/src/xoshiro/tests/testInt64.ml
new file mode 100644
index 0000000..4a9a9de
--- /dev/null
+++ b/src/xoshiro/tests/testInt64.ml
@@ -0,0 +1,20 @@
+open Xoshiro
+
+let test_compare nb f g =
+  for _ = 1 to nb do
+    assert (f () = g ())
+  done
+
+let ocaml_seed seed =
+  let s = ref seed in
+  for i = 0 to 3 do
+    X256pp.Int64.s.(i) <- Splitmix.Sm64.next s
+  done
+
+let () =
+  (* Chosen by fair dice rool. Guaranted to be random. *)
+  (* https://xkcd.com/221/ *)
+  let seed = 0xc6bb1e08d1a33f2fL in
+  Reference.seed seed;
+  ocaml_seed seed;
+  test_compare 1_000_000 Reference.next X256pp.Int64.next

From e7697eb71ec224e17d0a81993bc1b3296ca68b4e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Tue, 28 Apr 2020 01:17:32 +0200
Subject: [PATCH 07/26] Test X256pp.Int against reference implementation

---
 src/xoshiro/tests/dune       |  2 +-
 src/xoshiro/tests/testInt.ml | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 src/xoshiro/tests/testInt.ml

diff --git a/src/xoshiro/tests/dune b/src/xoshiro/tests/dune
index 76caeda..03ddcf3 100644
--- a/src/xoshiro/tests/dune
+++ b/src/xoshiro/tests/dune
@@ -1,3 +1,3 @@
 (tests
- (names testInt64)
+ (names testInt64 testInt)
  (libraries splitmix xoshiro))
diff --git a/src/xoshiro/tests/testInt.ml b/src/xoshiro/tests/testInt.ml
new file mode 100644
index 0000000..a195023
--- /dev/null
+++ b/src/xoshiro/tests/testInt.ml
@@ -0,0 +1,36 @@
+open Xoshiro
+
+let int_int_to_int64 (hi, lo) =
+  let open Int64 in
+  logxor (shift_left (of_int hi) 32) (of_int lo)
+
+let int64_to_int_int n =
+  let open Int64 in
+  let hi = to_int (shift_right_logical n 32) in
+  let lo = to_int (logand n 0xFFFFFFFFL) in
+  (hi, lo)
+
+let test_compare nb f g =
+  for _ = 1 to nb do
+    assert (f () = g ())
+  done
+
+let ocaml_seed seed =
+  let s = ref seed in
+  for i = 0 to 3 do
+    let hi, lo = Splitmix.Sm64.next s |> int64_to_int_int in
+    X256pp.Int.state.(2 * i) <- hi;
+    X256pp.Int.state.(2 * i + 1) <- lo
+  done
+
+let () =
+  (* Chosen by fair dice rool. Guaranted to be random. *)
+  (* https://xkcd.com/221/ *)
+  let seed = 0xc6bb1e08d1a33f2fL in
+  Reference.seed seed;
+  ocaml_seed seed;
+  test_compare
+    1_000_000
+    Reference.next
+    (fun () ->
+      X256pp.Int.next () |> int_int_to_int64)

From e1d51d18aa0c2eb6568a54849359b5a4dfaa4e37 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Tue, 28 Apr 2020 01:19:36 +0200
Subject: [PATCH 08/26] The c/ folder is obsolete

---
 c/.gitignore        |  3 ---
 c/Makefile          | 12 ------------
 c/ocamlrandom.c     | 24 ------------------------
 c/ocamlrandom.h     |  1 -
 c/testocamlrandom.c | 14 --------------
 c/testxoshiro.c     | 15 ---------------
 6 files changed, 69 deletions(-)
 delete mode 100644 c/.gitignore
 delete mode 100644 c/Makefile
 delete mode 100644 c/ocamlrandom.c
 delete mode 100644 c/ocamlrandom.h
 delete mode 100644 c/testocamlrandom.c
 delete mode 100644 c/testxoshiro.c

diff --git a/c/.gitignore b/c/.gitignore
deleted file mode 100644
index dba0160..0000000
--- a/c/.gitignore
+++ /dev/null
@@ -1,3 +0,0 @@
-/testocamlrandom
-/testxoshiro
-/testsplitmix
diff --git a/c/Makefile b/c/Makefile
deleted file mode 100644
index ef136ec..0000000
--- a/c/Makefile
+++ /dev/null
@@ -1,12 +0,0 @@
-all: testxoshiro testocamlrandom testsplitmix
-
-testxoshiro: testxoshiro.c xoshiro256pp.c xoshiro256pp.h
-	cc -o $@ $< xoshiro256pp.c
-
-testocamlrandom: testocamlrandom.c ocamlrandom.c ocamlrandom.h
-	cc -o $@ $< ocamlrandom.c
-
-clean:
-	rm -f testxoshiro testocamlrandom testsplitmix
-
-.PHONY: all clean
diff --git a/c/ocamlrandom.c b/c/ocamlrandom.c
deleted file mode 100644
index 6c90d48..0000000
--- a/c/ocamlrandom.c
+++ /dev/null
@@ -1,24 +0,0 @@
-static int s[55] = {
-  0x3ae2522b, 0x1d8d4634, 0x15b4fad0, 0x18b14ace, 0x12f8a3c4, 0x3b086c47,
-  0x16d467d6, 0x101d91c7, 0x321df177, 0x0176c193, 0x1ff72bf1, 0x1e889109,
-  0x0b464b18, 0x2b86b97c, 0x0891da48, 0x03137463, 0x085ac5a1, 0x15d61f2f,
-  0x3bced359, 0x29c1c132, 0x3a86766e, 0x366d8c86, 0x1f5b6222, 0x3ce1b59f,
-  0x2ebf78e1, 0x27cd1b86, 0x258f3dc3, 0x389a8194, 0x02e4c44c, 0x18c43f7d,
-  0x0f6e534f, 0x1e7df359, 0x055d0b7e, 0x10e84e7e, 0x126198e4, 0x0e7722cb,
-  0x1cbede28, 0x3391b964, 0x3d40e92a, 0x0c59933d, 0x0b8cd0b7, 0x24efff1c,
-  0x2803fdaa, 0x08ebc72e, 0x0f522e32, 0x05398edc, 0x2144a04c, 0x0aef3cbd,
-  0x01ad4719, 0x35b93cd6, 0x2a559d4f, 0x1e6fd768, 0x26e27f36, 0x186f18c3,
-  0x2fbf967a,
-};
-
-static int idx = 0;
-
-int bits() {
-  idx = (idx + 1) % 55;
-  int curval = s[idx];
-  int newval = s[(idx + 24) % 55] + (curval ^ ((curval >> 25) & 0x1F));
-  int newval30 = newval & 0x3FFFFFFF;
-  s[idx] = newval30;
-  return newval30;
-}
-
diff --git a/c/ocamlrandom.h b/c/ocamlrandom.h
deleted file mode 100644
index 6ca5c74..0000000
--- a/c/ocamlrandom.h
+++ /dev/null
@@ -1 +0,0 @@
-int bits();
diff --git a/c/testocamlrandom.c b/c/testocamlrandom.c
deleted file mode 100644
index 77bce0c..0000000
--- a/c/testocamlrandom.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <stdlib.h>
-#include <stdio.h>
-#include "ocamlrandom.h"
-
-int main(int argc, char* argv[]) {
-  int n = 10;
-  if (argc == 2) n = atoi(argv[1]);
-
-  for (int i = 0; i < n; i++)
-    printf("%08x\n", bits());
-
-  return 0;
-}
-
diff --git a/c/testxoshiro.c b/c/testxoshiro.c
deleted file mode 100644
index 39bdb2d..0000000
--- a/c/testxoshiro.c
+++ /dev/null
@@ -1,15 +0,0 @@
-#include <assert.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdint.h>
-#include "xoshiro256pp.h"
-
-int main(int argc, const char* argv[]) {
-  int n = 10;
-  if (argc == 2) n = atoi(argv[1]);
-
-  for (int i = 0; i < n; i++)
-    printf("%016lx\n", next());
-
-  return 0;
-}

From 640b0a2de48bc3f02e8f26955e2fcd7b11f3fde6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Tue, 28 Apr 2020 23:29:28 +0200
Subject: [PATCH 09/26] Remove obsolete tests

---
 Makefile                         | 12 ++++++++++++
 src/dune-project => dune-project |  0
 src/Makefile                     | 14 --------------
 src/tests/dune                   | 13 -------------
 src/tests/ocamlrandom.ml         | 10 ----------
 src/tests/splitmix.ml            | 13 -------------
 src/tests/xoshiro.ml             | 15 ---------------
 7 files changed, 12 insertions(+), 65 deletions(-)
 create mode 100644 Makefile
 rename src/dune-project => dune-project (100%)
 delete mode 100644 src/Makefile
 delete mode 100644 src/tests/dune
 delete mode 100644 src/tests/ocamlrandom.ml
 delete mode 100644 src/tests/splitmix.ml
 delete mode 100644 src/tests/xoshiro.ml

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..8d40edc
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,12 @@
+all: tests bench
+
+test:
+	dune test
+
+bench:
+	dune build ./bench.exe
+
+clean:
+	dune clean
+
+.PHONY: all clean bench test
diff --git a/src/dune-project b/dune-project
similarity index 100%
rename from src/dune-project
rename to dune-project
diff --git a/src/Makefile b/src/Makefile
deleted file mode 100644
index 1c48a5c..0000000
--- a/src/Makefile
+++ /dev/null
@@ -1,14 +0,0 @@
-all: tests bench
-
-tests:
-	dune build ./tests/ocamlrandom.exe
-	dune build ./tests/xoshiro.exe
-	dune build ./tests/splitmix.exe
-
-bench:
-	dune build ./bench.exe
-
-clean:
-	dune clean
-
-.PHONY: all clean bench tests
diff --git a/src/tests/dune b/src/tests/dune
deleted file mode 100644
index 5189e02..0000000
--- a/src/tests/dune
+++ /dev/null
@@ -1,13 +0,0 @@
-(executable
- (name xoshiro)
- (modules xoshiro)
- (libraries xoshiro))
-
-(executable
- (name ocamlrandom)
- (modules ocamlrandom))
-
-(executable
- (name splitmix)
- (modules splitmix)
- (libraries splitmix))
diff --git a/src/tests/ocamlrandom.ml b/src/tests/ocamlrandom.ml
deleted file mode 100644
index 00344a3..0000000
--- a/src/tests/ocamlrandom.ml
+++ /dev/null
@@ -1,10 +0,0 @@
-let () =
-  let n =
-    if Array.length Sys.argv = 2
-    then int_of_string Sys.argv.(1)
-    else 10
-  in
-
-  for _ = 1 to n do
-    Format.printf "%08x\n" (Random.bits ())
-  done
diff --git a/src/tests/splitmix.ml b/src/tests/splitmix.ml
deleted file mode 100644
index eb3e35a..0000000
--- a/src/tests/splitmix.ml
+++ /dev/null
@@ -1,13 +0,0 @@
-open Splitmix
-
-let () =
-  let n =
-    if Array.length Sys.argv = 2
-    then int_of_string Sys.argv.(1)
-    else 10
-  in
-
-  let state = ref 0xdead42beef37ca7aL in
-  for _ = 1 to n do
-    Format.printf "%016Lx@." (Sm64.next state)
-  done
diff --git a/src/tests/xoshiro.ml b/src/tests/xoshiro.ml
deleted file mode 100644
index e615baa..0000000
--- a/src/tests/xoshiro.ml
+++ /dev/null
@@ -1,15 +0,0 @@
-open Xoshiro
-
-let () =
-  let n =
-    if Array.length Sys.argv = 2
-    then int_of_string Sys.argv.(1)
-    else 10
-  in
-
-  for _ = 1 to n do
-    let hi, lo = X256pp.Int.next () in
-    Format.printf "%08x%08x " hi lo;
-    Format.printf "%016Lx " (X256pp.Int64.next ());
-    Format.printf "%08x@." (X256pp.C.bits ())
-  done

From adc429d4edced32592a1ddfcc98d7bbdee0764c9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Wed, 6 May 2020 15:11:45 +0200
Subject: [PATCH 10/26] Remove duplicate code

---
 src/splitmix/dune        |  8 +++++++-
 src/splitmix/reference.c | 16 ++++++++++++----
 src/splitmix/reference.h |  4 +++-
 src/splitmix/stubs.c     |  7 ++++---
 src/xoshiro/dune         |  9 ++++++++-
 src/xoshiro/reference.c  | 10 ++--------
 6 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/src/splitmix/dune b/src/splitmix/dune
index 62a2772..fbd8277 100644
--- a/src/splitmix/dune
+++ b/src/splitmix/dune
@@ -1,9 +1,15 @@
 (library
  (name splitmix)
- (foreign_stubs (language c) (names reference stubs))
+ (foreign_archives splitmix)
+ (foreign_stubs (language c) (names stubs))
  (libraries makeRandom)
  (modules :standard \ Tests))
 
+(foreign_library
+ (archive_name splitmix)
+ (language c)
+ (names reference))
+
 (test
  (name tests)
  (modules Tests)
diff --git a/src/splitmix/reference.c b/src/splitmix/reference.c
index d653006..f9897ff 100644
--- a/src/splitmix/reference.c
+++ b/src/splitmix/reference.c
@@ -2,12 +2,20 @@
 
 #include <stdint.h>
 
-uint64_t sm64_state; /* The state can be seeded with any value. */
-
-uint64_t sm64_next() {
-	uint64_t z = (sm64_state += 0x9e3779b97f4a7c15);
+uint64_t sm64_next_stateless(uint64_t* s) {
+	uint64_t z = (*s += 0x9e3779b97f4a7c15);
 	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
 	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
 	return z ^ (z >> 31);
 }
 
+static uint64_t state; /* The state can be seeded with any value. */
+
+void sm64_seed(uint64_t seed) {
+  state = seed;
+}
+
+uint64_t sm64_next() {
+  return sm64_next_stateless(&state);
+}
+
diff --git a/src/splitmix/reference.h b/src/splitmix/reference.h
index aef2394..0c8e72f 100644
--- a/src/splitmix/reference.h
+++ b/src/splitmix/reference.h
@@ -3,7 +3,9 @@
 
 #include <stdint.h>
 
-uint64_t sm64_state;
+uint64_t sm64_next_stateless(uint64_t*);
+
+void sm64_seed(uint64_t);
 uint64_t sm64_next();
 
 #endif
diff --git a/src/splitmix/stubs.c b/src/splitmix/stubs.c
index daf31ed..b5e5595 100644
--- a/src/splitmix/stubs.c
+++ b/src/splitmix/stubs.c
@@ -1,15 +1,16 @@
+#include <stdint.h>
+#include "reference.h"
+
 #define CAML_NAME_SPACE
 #include <caml/mlvalues.h>
 #include <caml/memory.h>
 #include <caml/alloc.h>
-#include <stdint.h>
-#include "reference.h"
 
 CAMLprim value caml_sm64_seed(value seed) {
   CAMLparam1(seed);
   int64_t x = Int64_val(seed);
   // reinterpret x as an unsigned integer
-  sm64_state = *(uint64_t*)(&x);
+  sm64_seed(*(uint64_t*)(&x));
   CAMLreturn(Val_unit);
 }
 
diff --git a/src/xoshiro/dune b/src/xoshiro/dune
index ceca707..ef6506c 100644
--- a/src/xoshiro/dune
+++ b/src/xoshiro/dune
@@ -1,3 +1,10 @@
 (library
  (name xoshiro)
- (foreign_stubs (language c) (names stubs reference)))
+ (foreign_archives xoshiro)
+ (foreign_stubs (language c) (names stubs)))
+
+(foreign_library
+ (archive_name xoshiro)
+ (language c)
+ (flags -lsplitmix)
+ (names reference))
diff --git a/src/xoshiro/reference.c b/src/xoshiro/reference.c
index dc03d63..0d0984f 100644
--- a/src/xoshiro/reference.c
+++ b/src/xoshiro/reference.c
@@ -1,6 +1,7 @@
 // Reference:  http://prng.di.unimi.it/xoshiro256plusplus.c
 
 #include <stdint.h>
+#include "../splitmix/reference.h"
 
 static inline uint64_t rotl(const uint64_t x, int k) {
 	return (x << k) | (x >> (64 - k));
@@ -30,16 +31,9 @@ uint64_t x256pp_next(void) {
 	return result;
 }
 
-static uint64_t splitmix64(uint64_t* s) {
-	uint64_t z = (*s += 0x9e3779b97f4a7c15);
-	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
-	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
-	return z ^ (z >> 31);
-}
-
 void x256pp_seed(uint64_t seed) {
   uint64_t s = seed;
   for (int i = 0; i < 4; i++)
-    x256pp_state[i] = splitmix64(&s);
+    x256pp_state[i] = sm64_next_stateless(&s);
 }
 

From e29fb078602201437b55291fbd7c45e48a284652 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Fri, 15 May 2020 12:20:25 +0200
Subject: [PATCH 11/26] git mv * prng/

---
 Makefile                                     | 12 ------------
 dune-project => prng/dune-project            |  0
 {src => prng/src}/.gitignore                 |  0
 {src => prng/src}/bench.ml                   |  0
 {src => prng/src}/dune                       |  0
 {src => prng/src}/make-random/bench.ml       |  0
 {src => prng/src}/make-random/dune           |  0
 {src => prng/src}/make-random/makeRandom.ml  |  0
 {src => prng/src}/make-random/test.ml        |  0
 {src => prng/src}/splitmix/dune              |  0
 {src => prng/src}/splitmix/reference.c       |  0
 {src => prng/src}/splitmix/reference.h       |  0
 {src => prng/src}/splitmix/reference.ml      |  0
 {src => prng/src}/splitmix/sm64.ml           |  0
 {src => prng/src}/splitmix/stubs.c           |  0
 {src => prng/src}/splitmix/tests.ml          |  0
 {src => prng/src}/xoshiro/dune               |  0
 {src => prng/src}/xoshiro/reference.c        |  0
 {src => prng/src}/xoshiro/reference.h        |  0
 {src => prng/src}/xoshiro/reference.ml       |  0
 {src => prng/src}/xoshiro/stubs.c            |  0
 {src => prng/src}/xoshiro/tests/dune         |  0
 {src => prng/src}/xoshiro/tests/testInt.ml   |  0
 {src => prng/src}/xoshiro/tests/testInt64.ml |  0
 {src => prng/src}/xoshiro/x256pp.ml          |  0
 25 files changed, 12 deletions(-)
 delete mode 100644 Makefile
 rename dune-project => prng/dune-project (100%)
 rename {src => prng/src}/.gitignore (100%)
 rename {src => prng/src}/bench.ml (100%)
 rename {src => prng/src}/dune (100%)
 rename {src => prng/src}/make-random/bench.ml (100%)
 rename {src => prng/src}/make-random/dune (100%)
 rename {src => prng/src}/make-random/makeRandom.ml (100%)
 rename {src => prng/src}/make-random/test.ml (100%)
 rename {src => prng/src}/splitmix/dune (100%)
 rename {src => prng/src}/splitmix/reference.c (100%)
 rename {src => prng/src}/splitmix/reference.h (100%)
 rename {src => prng/src}/splitmix/reference.ml (100%)
 rename {src => prng/src}/splitmix/sm64.ml (100%)
 rename {src => prng/src}/splitmix/stubs.c (100%)
 rename {src => prng/src}/splitmix/tests.ml (100%)
 rename {src => prng/src}/xoshiro/dune (100%)
 rename {src => prng/src}/xoshiro/reference.c (100%)
 rename {src => prng/src}/xoshiro/reference.h (100%)
 rename {src => prng/src}/xoshiro/reference.ml (100%)
 rename {src => prng/src}/xoshiro/stubs.c (100%)
 rename {src => prng/src}/xoshiro/tests/dune (100%)
 rename {src => prng/src}/xoshiro/tests/testInt.ml (100%)
 rename {src => prng/src}/xoshiro/tests/testInt64.ml (100%)
 rename {src => prng/src}/xoshiro/x256pp.ml (100%)

diff --git a/Makefile b/Makefile
deleted file mode 100644
index 8d40edc..0000000
--- a/Makefile
+++ /dev/null
@@ -1,12 +0,0 @@
-all: tests bench
-
-test:
-	dune test
-
-bench:
-	dune build ./bench.exe
-
-clean:
-	dune clean
-
-.PHONY: all clean bench test
diff --git a/dune-project b/prng/dune-project
similarity index 100%
rename from dune-project
rename to prng/dune-project
diff --git a/src/.gitignore b/prng/src/.gitignore
similarity index 100%
rename from src/.gitignore
rename to prng/src/.gitignore
diff --git a/src/bench.ml b/prng/src/bench.ml
similarity index 100%
rename from src/bench.ml
rename to prng/src/bench.ml
diff --git a/src/dune b/prng/src/dune
similarity index 100%
rename from src/dune
rename to prng/src/dune
diff --git a/src/make-random/bench.ml b/prng/src/make-random/bench.ml
similarity index 100%
rename from src/make-random/bench.ml
rename to prng/src/make-random/bench.ml
diff --git a/src/make-random/dune b/prng/src/make-random/dune
similarity index 100%
rename from src/make-random/dune
rename to prng/src/make-random/dune
diff --git a/src/make-random/makeRandom.ml b/prng/src/make-random/makeRandom.ml
similarity index 100%
rename from src/make-random/makeRandom.ml
rename to prng/src/make-random/makeRandom.ml
diff --git a/src/make-random/test.ml b/prng/src/make-random/test.ml
similarity index 100%
rename from src/make-random/test.ml
rename to prng/src/make-random/test.ml
diff --git a/src/splitmix/dune b/prng/src/splitmix/dune
similarity index 100%
rename from src/splitmix/dune
rename to prng/src/splitmix/dune
diff --git a/src/splitmix/reference.c b/prng/src/splitmix/reference.c
similarity index 100%
rename from src/splitmix/reference.c
rename to prng/src/splitmix/reference.c
diff --git a/src/splitmix/reference.h b/prng/src/splitmix/reference.h
similarity index 100%
rename from src/splitmix/reference.h
rename to prng/src/splitmix/reference.h
diff --git a/src/splitmix/reference.ml b/prng/src/splitmix/reference.ml
similarity index 100%
rename from src/splitmix/reference.ml
rename to prng/src/splitmix/reference.ml
diff --git a/src/splitmix/sm64.ml b/prng/src/splitmix/sm64.ml
similarity index 100%
rename from src/splitmix/sm64.ml
rename to prng/src/splitmix/sm64.ml
diff --git a/src/splitmix/stubs.c b/prng/src/splitmix/stubs.c
similarity index 100%
rename from src/splitmix/stubs.c
rename to prng/src/splitmix/stubs.c
diff --git a/src/splitmix/tests.ml b/prng/src/splitmix/tests.ml
similarity index 100%
rename from src/splitmix/tests.ml
rename to prng/src/splitmix/tests.ml
diff --git a/src/xoshiro/dune b/prng/src/xoshiro/dune
similarity index 100%
rename from src/xoshiro/dune
rename to prng/src/xoshiro/dune
diff --git a/src/xoshiro/reference.c b/prng/src/xoshiro/reference.c
similarity index 100%
rename from src/xoshiro/reference.c
rename to prng/src/xoshiro/reference.c
diff --git a/src/xoshiro/reference.h b/prng/src/xoshiro/reference.h
similarity index 100%
rename from src/xoshiro/reference.h
rename to prng/src/xoshiro/reference.h
diff --git a/src/xoshiro/reference.ml b/prng/src/xoshiro/reference.ml
similarity index 100%
rename from src/xoshiro/reference.ml
rename to prng/src/xoshiro/reference.ml
diff --git a/src/xoshiro/stubs.c b/prng/src/xoshiro/stubs.c
similarity index 100%
rename from src/xoshiro/stubs.c
rename to prng/src/xoshiro/stubs.c
diff --git a/src/xoshiro/tests/dune b/prng/src/xoshiro/tests/dune
similarity index 100%
rename from src/xoshiro/tests/dune
rename to prng/src/xoshiro/tests/dune
diff --git a/src/xoshiro/tests/testInt.ml b/prng/src/xoshiro/tests/testInt.ml
similarity index 100%
rename from src/xoshiro/tests/testInt.ml
rename to prng/src/xoshiro/tests/testInt.ml
diff --git a/src/xoshiro/tests/testInt64.ml b/prng/src/xoshiro/tests/testInt64.ml
similarity index 100%
rename from src/xoshiro/tests/testInt64.ml
rename to prng/src/xoshiro/tests/testInt64.ml
diff --git a/src/xoshiro/x256pp.ml b/prng/src/xoshiro/x256pp.ml
similarity index 100%
rename from src/xoshiro/x256pp.ml
rename to prng/src/xoshiro/x256pp.ml

From b2565441743715f22a06e0a28bd1c3e3bc0f8572 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Fri, 15 May 2020 16:05:11 +0200
Subject: [PATCH 12/26] Remove CAMLprim everywhere

---
 prng/src/splitmix/stubs.c |  4 ++--
 prng/src/xoshiro/stubs.c  | 10 +++++-----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/prng/src/splitmix/stubs.c b/prng/src/splitmix/stubs.c
index b5e5595..d03b481 100644
--- a/prng/src/splitmix/stubs.c
+++ b/prng/src/splitmix/stubs.c
@@ -6,7 +6,7 @@
 #include <caml/memory.h>
 #include <caml/alloc.h>
 
-CAMLprim value caml_sm64_seed(value seed) {
+value caml_sm64_seed(value seed) {
   CAMLparam1(seed);
   int64_t x = Int64_val(seed);
   // reinterpret x as an unsigned integer
@@ -14,7 +14,7 @@ CAMLprim value caml_sm64_seed(value seed) {
   CAMLreturn(Val_unit);
 }
 
-CAMLprim value caml_sm64_next(value unit) {
+value caml_sm64_next(value unit) {
   CAMLparam1(unit);
   uint64_t x = sm64_next();
   // reinterpret x as a signed integer
diff --git a/prng/src/xoshiro/stubs.c b/prng/src/xoshiro/stubs.c
index 2c872d3..ab46b1a 100644
--- a/prng/src/xoshiro/stubs.c
+++ b/prng/src/xoshiro/stubs.c
@@ -5,7 +5,7 @@
 #include <stdint.h>
 #include "reference.h"
 
-CAMLprim value caml_x256pp_seed(value seed) {
+value caml_x256pp_seed(value seed) {
   CAMLparam1(seed);
   int64_t x = Int64_val(seed);
   // reinterpret x as an unsigned integer
@@ -13,7 +13,7 @@ CAMLprim value caml_x256pp_seed(value seed) {
   CAMLreturn(Val_unit);
 }
 
-CAMLprim value caml_x256pp_next(value unit) {
+value caml_x256pp_next(value unit) {
   CAMLparam1(unit);
   uint64_t x = x256pp_next();
   // reinterpret x as a signed integer
@@ -21,19 +21,19 @@ CAMLprim value caml_x256pp_next(value unit) {
   CAMLreturn(res);
 }
 
-CAMLprim value caml_x256pp_bits(value unit) {
+value caml_x256pp_bits(value unit) {
   CAMLparam1(unit);
   intnat res = x256pp_next() >> 34;
   CAMLreturn(Val_long(res));
 }
 
-CAMLprim value caml_x256pp_bits62(value unit) {
+value caml_x256pp_bits62(value unit) {
   CAMLparam1(unit);
   long res = x256pp_next() >> 2;
   CAMLreturn(Val_long(res));
 }
 
-CAMLprim value caml_x256pp_double(value f) {
+value caml_x256pp_double(value f) {
   CAMLparam1(f);
   double res = (x256pp_next() >> 11) * 0x1.0p-53;
   res *= Double_val(f);

From 76a40dd506bad9a7ed070273ec24e0f9a9e0465a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Fri, 15 May 2020 16:18:48 +0200
Subject: [PATCH 13/26] consistency: #define WHATEVER_H 1

---
 prng/src/splitmix/reference.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/prng/src/splitmix/reference.h b/prng/src/splitmix/reference.h
index 0c8e72f..311677c 100644
--- a/prng/src/splitmix/reference.h
+++ b/prng/src/splitmix/reference.h
@@ -1,5 +1,5 @@
 #ifndef SPLITMIX64_H
-#define SPLITMIX64_H
+#define SPLITMIX64_H 1
 
 #include <stdint.h>
 

From 050a066e084a708809bb88322fe429fe4f4bb071 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Fri, 15 May 2020 16:48:47 +0200
Subject: [PATCH 14/26] mv some stuff WIP

---
 prng/src/xoshiro/tests/dune                       | 2 +-
 prng/src/xoshiro/tests/{testInt.ml => int.ml}     | 4 ++--
 prng/src/xoshiro/tests/{testInt64.ml => int64.ml} | 0
 3 files changed, 3 insertions(+), 3 deletions(-)
 rename prng/src/xoshiro/tests/{testInt.ml => int.ml} (93%)
 rename prng/src/xoshiro/tests/{testInt64.ml => int64.ml} (100%)

diff --git a/prng/src/xoshiro/tests/dune b/prng/src/xoshiro/tests/dune
index 03ddcf3..b7aba12 100644
--- a/prng/src/xoshiro/tests/dune
+++ b/prng/src/xoshiro/tests/dune
@@ -1,3 +1,3 @@
 (tests
- (names testInt64 testInt)
+ (names int64 int)
  (libraries splitmix xoshiro))
diff --git a/prng/src/xoshiro/tests/testInt.ml b/prng/src/xoshiro/tests/int.ml
similarity index 93%
rename from prng/src/xoshiro/tests/testInt.ml
rename to prng/src/xoshiro/tests/int.ml
index a195023..52460b0 100644
--- a/prng/src/xoshiro/tests/testInt.ml
+++ b/prng/src/xoshiro/tests/int.ml
@@ -1,11 +1,11 @@
 open Xoshiro
 
 let int_int_to_int64 (hi, lo) =
-  let open Int64 in
+  let open Stdlib.Int64 in
   logxor (shift_left (of_int hi) 32) (of_int lo)
 
 let int64_to_int_int n =
-  let open Int64 in
+  let open Stdlib.Int64 in
   let hi = to_int (shift_right_logical n 32) in
   let lo = to_int (logand n 0xFFFFFFFFL) in
   (hi, lo)
diff --git a/prng/src/xoshiro/tests/testInt64.ml b/prng/src/xoshiro/tests/int64.ml
similarity index 100%
rename from prng/src/xoshiro/tests/testInt64.ml
rename to prng/src/xoshiro/tests/int64.ml

From 0012f456206fd768072fb6b77fb72b4126855e2b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Fri, 15 May 2020 17:20:45 +0200
Subject: [PATCH 15/26] Hide x256pp_state (and fix a linker issue)

---
 prng/src/xoshiro/reference.c | 2 +-
 prng/src/xoshiro/reference.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/prng/src/xoshiro/reference.c b/prng/src/xoshiro/reference.c
index 0d0984f..6811f84 100644
--- a/prng/src/xoshiro/reference.c
+++ b/prng/src/xoshiro/reference.c
@@ -7,7 +7,7 @@ static inline uint64_t rotl(const uint64_t x, int k) {
 	return (x << k) | (x >> (64 - k));
 }
 
-uint64_t x256pp_state[4] = {
+static uint64_t x256pp_state[4] = {
   0xd430ebc2f4d9e7b8,
   0x44815975ddd19d52,
   0xbb18c2b0b18d0bfe,
diff --git a/prng/src/xoshiro/reference.h b/prng/src/xoshiro/reference.h
index ec5d146..fe5ad8f 100644
--- a/prng/src/xoshiro/reference.h
+++ b/prng/src/xoshiro/reference.h
@@ -3,8 +3,8 @@
 
 #include <stdint.h>
 
-uint64_t x256pp_state[4];
 uint64_t x256pp_next();
 void x256pp_seed(uint64_t);
 
 #endif
+

From 2add6b4a2751dafa13727b26fd519441265160d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Fri, 15 May 2020 17:23:21 +0200
Subject: [PATCH 16/26] More consistent naming of tests

---
 prng/src/splitmix/dune                        | 8 +-------
 prng/src/splitmix/tests/dune                  | 3 +++
 prng/src/splitmix/{tests.ml => tests/sm64.ml} | 0
 3 files changed, 4 insertions(+), 7 deletions(-)
 create mode 100644 prng/src/splitmix/tests/dune
 rename prng/src/splitmix/{tests.ml => tests/sm64.ml} (100%)

diff --git a/prng/src/splitmix/dune b/prng/src/splitmix/dune
index fbd8277..a314c11 100644
--- a/prng/src/splitmix/dune
+++ b/prng/src/splitmix/dune
@@ -2,15 +2,9 @@
  (name splitmix)
  (foreign_archives splitmix)
  (foreign_stubs (language c) (names stubs))
- (libraries makeRandom)
- (modules :standard \ Tests))
+ (libraries makeRandom))
 
 (foreign_library
  (archive_name splitmix)
  (language c)
  (names reference))
-
-(test
- (name tests)
- (modules Tests)
- (libraries splitmix))
diff --git a/prng/src/splitmix/tests/dune b/prng/src/splitmix/tests/dune
new file mode 100644
index 0000000..8b5b3e7
--- /dev/null
+++ b/prng/src/splitmix/tests/dune
@@ -0,0 +1,3 @@
+(test
+ (name sm64)
+ (libraries splitmix))
diff --git a/prng/src/splitmix/tests.ml b/prng/src/splitmix/tests/sm64.ml
similarity index 100%
rename from prng/src/splitmix/tests.ml
rename to prng/src/splitmix/tests/sm64.ml

From 7bed7ad37851dc8f8af861f726fbbde58ffa55aa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Fri, 15 May 2020 17:24:45 +0200
Subject: [PATCH 17/26] mv dune-project back to the root of the repository

---
 prng/dune-project => dune-project | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename prng/dune-project => dune-project (100%)

diff --git a/prng/dune-project b/dune-project
similarity index 100%
rename from prng/dune-project
rename to dune-project

From c452226407198d50945d5a3cb8380661199a2b92 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Mon, 18 May 2020 14:34:13 +0200
Subject: [PATCH 18/26] Internal testutils library

---
 .../splitmix/tests/{sm64.ml => sm64_ocaml.ml} |  0
 prng/src/testutils/dune                       |  8 +++
 prng/src/testutils/testutils.c                | 52 +++++++++++++++++++
 prng/src/testutils/testutils.h                |  7 +++
 prng/src/testutils/testutils.ml               | 27 ++++++++++
 5 files changed, 94 insertions(+)
 rename prng/src/splitmix/tests/{sm64.ml => sm64_ocaml.ml} (100%)
 create mode 100644 prng/src/testutils/dune
 create mode 100644 prng/src/testutils/testutils.c
 create mode 100644 prng/src/testutils/testutils.h
 create mode 100644 prng/src/testutils/testutils.ml

diff --git a/prng/src/splitmix/tests/sm64.ml b/prng/src/splitmix/tests/sm64_ocaml.ml
similarity index 100%
rename from prng/src/splitmix/tests/sm64.ml
rename to prng/src/splitmix/tests/sm64_ocaml.ml
diff --git a/prng/src/testutils/dune b/prng/src/testutils/dune
new file mode 100644
index 0000000..f7f5dce
--- /dev/null
+++ b/prng/src/testutils/dune
@@ -0,0 +1,8 @@
+(foreign_library
+ (archive_name testutils)
+ (language c)
+ (flags -Wall -Wextra -Wpedantic)
+ (names testutils))
+
+(library
+ (name testutils))
diff --git a/prng/src/testutils/testutils.c b/prng/src/testutils/testutils.c
new file mode 100644
index 0000000..9b7b233
--- /dev/null
+++ b/prng/src/testutils/testutils.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+int usage(const char* prog_name) {
+  fprintf(stderr, "%s [--seed=SEED] [--nb=N]\n", prog_name);
+  return 1;
+}
+
+int testutils_run(
+    int argc, char* argv[], void(*seed_func)(uint64_t), uint64_t(*next)(void)
+) {
+  long nb_iterations = -1;
+  uint64_t seed = 0xdd6d0e2e849e51ad;
+
+  struct option long_options[] = {
+    {"seed", optional_argument, NULL, 's'},
+    {"nb", optional_argument, NULL, 'n'},
+  };
+
+  while (1) {
+    int option_index = 0;
+    int c = getopt_long(argc, argv, "", long_options, &option_index);
+    char* endptr;
+    if (c == -1) break;
+    switch (c) {
+      case 's':
+        if (optarg == NULL) return usage(argv[0]);
+        seed = strtoull(optarg, &endptr, 10);
+        if (endptr == optarg || *endptr != '\0') return usage(argv[0]);
+        break;
+      case 'n':
+        if (optarg == NULL) return usage(argv[0]);
+        nb_iterations = strtol(optarg, &endptr, 10);
+        if (endptr == optarg || *endptr != '\0') return usage(argv[0]);
+        break;
+      default:
+        return usage(argv[0]);
+    }
+  }
+
+  if (optind < argc) return usage(argv[0]);
+
+  seed_func(seed);
+  for (long i = 0; i != nb_iterations; i++) {
+    printf("%lx\n", next());
+  }
+
+  return 0;
+}
+
diff --git a/prng/src/testutils/testutils.h b/prng/src/testutils/testutils.h
new file mode 100644
index 0000000..d60fcc4
--- /dev/null
+++ b/prng/src/testutils/testutils.h
@@ -0,0 +1,7 @@
+#ifndef TESTUTILS_H
+#define TESTUTILS_H 1
+
+#include <stdint.h>
+int testutils_run(int, char**, void(*)(uint64_t), uint64_t(*)(void));
+
+#endif
diff --git a/prng/src/testutils/testutils.ml b/prng/src/testutils/testutils.ml
new file mode 100644
index 0000000..2e43091
--- /dev/null
+++ b/prng/src/testutils/testutils.ml
@@ -0,0 +1,27 @@
+let run ~seed_f ~next =
+  let seed = ref 0xdd6d0e2e849e51adL in
+  let nb_iterations = ref (-1) in
+
+  let speclist = [
+    (
+      "--nb",
+      Arg.Set_int nb_iterations,
+      " Number of random integers to generate"
+    );
+    (
+      "--seed",
+      Arg.String (fun n -> seed := Int64.of_string n),
+      " 64-bit seed");
+  ] in
+
+  let usage =
+    Format.sprintf "%s [--seed=SEED] [--nb=N]" Sys.argv.(0)
+  in
+
+  Arg.parse speclist (fun _ -> invalid_arg "run") usage;
+  seed_f !seed;
+  let i = ref 0 in
+  while !i <> !nb_iterations do
+    Format.printf "%Lx@." (next ());
+    incr i
+  done

From f3d83cf1a717ca595d6e2865ce493a5a99dff6b2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Mon, 18 May 2020 14:36:04 +0200
Subject: [PATCH 19/26] Test: diff the output pure ocaml vs. pure C code

---
 prng/src/splitmix/tests/dune          | 16 +++++++++++++---
 prng/src/splitmix/tests/sm64_c.c      | 11 +++++++++++
 prng/src/splitmix/tests/sm64_ocaml.ml | 19 ++++---------------
 3 files changed, 28 insertions(+), 18 deletions(-)
 create mode 100644 prng/src/splitmix/tests/sm64_c.c

diff --git a/prng/src/splitmix/tests/dune b/prng/src/splitmix/tests/dune
index 8b5b3e7..0b7f5c0 100644
--- a/prng/src/splitmix/tests/dune
+++ b/prng/src/splitmix/tests/dune
@@ -1,3 +1,13 @@
-(test
- (name sm64)
- (libraries splitmix))
+(executable
+ (name sm64_ocaml)
+ (libraries splitmix testutils))
+
+(rule
+ (target sm64_c.exe)
+ (deps sm64_c.c ../../testutils/libtestutils.a ../libsplitmix.a)
+ (action
+  (run cc -Wall -Wextra -Wpedantic -o %{target} %{deps})))
+
+(rule (with-stdout-to sm64_ocaml.output (run ./sm64_ocaml.exe --nb=1000)))
+(rule (with-stdout-to sm64_c.output     (run ./sm64_c.exe     --nb=1000)))
+(rule (alias runtest) (action (diff sm64_ocaml.output sm64_c.output)))
diff --git a/prng/src/splitmix/tests/sm64_c.c b/prng/src/splitmix/tests/sm64_c.c
new file mode 100644
index 0000000..57d89e2
--- /dev/null
+++ b/prng/src/splitmix/tests/sm64_c.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include "../reference.h"
+#include "../../testutils/testutils.h"
+
+int main(int argc, char* argv[]) {
+  return testutils_run(argc, argv, sm64_seed, sm64_next);
+}
diff --git a/prng/src/splitmix/tests/sm64_ocaml.ml b/prng/src/splitmix/tests/sm64_ocaml.ml
index 197f7b0..8cd0e97 100644
--- a/prng/src/splitmix/tests/sm64_ocaml.ml
+++ b/prng/src/splitmix/tests/sm64_ocaml.ml
@@ -1,18 +1,7 @@
 open Splitmix
 
-let test_compare nb f g =
-  for _ = 1 to nb do
-    assert (f () = g ())
-  done
-
 let () =
-  (* Chosen by fair dice rool. Guaranted to be random. *)
-  (* https://xkcd.com/221/ *)
-  let seed = 0xdd6d0e2e849e51adL in
-  let ocaml_state = ref seed in
-
-  Reference.seed seed;
-  test_compare
-    1_000_000
-    Reference.next
-    (fun () -> Sm64.next ocaml_state)
+  let state = ref 0L in
+  Testutils.run
+    ~seed_f:(fun s -> state := s)
+    ~next:(fun () -> Sm64.next state)

From 05999c06320fb854bb59f522c4717bd7f4f8d0ec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Mon, 18 May 2020 17:46:17 +0200
Subject: [PATCH 20/26] Test all rngs against a C reference implementation

---
 prng/src/bench.ml                         | 11 ------
 prng/src/splitmix/dune                    |  7 ----
 prng/src/splitmix/reference.ml            |  2 --
 prng/src/splitmix/stubs.c                 | 24 -------------
 prng/src/splitmix/tests/dune              |  2 +-
 prng/src/splitmix/{ => tests}/reference.c | 17 ++++-----
 prng/src/splitmix/{ => tests}/reference.h |  3 --
 prng/src/splitmix/tests/sm64_c.c          |  7 +---
 prng/src/xoshiro/dune                     |  9 +----
 prng/src/xoshiro/reference.ml             |  2 --
 prng/src/xoshiro/stubs.c                  | 42 -----------------------
 prng/src/xoshiro/tests/dune               | 18 ++++++++--
 prng/src/xoshiro/tests/int.ml             | 18 ++--------
 prng/src/xoshiro/tests/int64.ml           | 24 ++++---------
 prng/src/xoshiro/{ => tests}/reference.c  |  8 ++++-
 prng/src/xoshiro/{ => tests}/reference.h  |  0
 prng/src/xoshiro/tests/x256pp_c.c         |  6 ++++
 prng/src/xoshiro/x256pp.ml                |  6 ----
 18 files changed, 48 insertions(+), 158 deletions(-)
 delete mode 100644 prng/src/splitmix/reference.ml
 delete mode 100644 prng/src/splitmix/stubs.c
 rename prng/src/splitmix/{ => tests}/reference.c (53%)
 rename prng/src/splitmix/{ => tests}/reference.h (73%)
 delete mode 100644 prng/src/xoshiro/reference.ml
 delete mode 100644 prng/src/xoshiro/stubs.c
 rename prng/src/xoshiro/{ => tests}/reference.c (80%)
 rename prng/src/xoshiro/{ => tests}/reference.h (100%)
 create mode 100644 prng/src/xoshiro/tests/x256pp_c.c

diff --git a/prng/src/bench.ml b/prng/src/bench.ml
index 1ed8f82..2177d43 100644
--- a/prng/src/bench.ml
+++ b/prng/src/bench.ml
@@ -5,7 +5,6 @@ module Command = Core.Command
 module Random_Stdlib       = MakeRandom.Basic(Random)
 module Random_X256pp_Int   = MakeRandom.Basic(X256pp.Int)
 module Random_X256pp_Int64 = MakeRandom.Basic(X256pp.Int64)
-module Random_X256pp_C     = MakeRandom.Basic(X256pp.C)
 
 let bits () =
   Command.run @@ B.make_command [
@@ -17,10 +16,6 @@ let bits () =
         X256pp.Int64.bits ());
     B.Test.create ~name:"X256pp.Int64.bits62" (fun () ->
         X256pp.Int64.bits62 ());
-    B.Test.create ~name:"X256pp.C.bits" (fun () ->
-        X256pp.C.bits ());
-    B.Test.create ~name:"X256pp.C.bits62" (fun () ->
-        X256pp.C.bits62 ());
   ]
 
 let float () =
@@ -29,14 +24,10 @@ let float () =
         Random.float 1.);
     B.Test.create ~name:"X256pp.Int64.float" (fun () ->
         X256pp.Int64.float 1.);
-    B.Test.create ~name:"X256pp.C.float" (fun () ->
-        X256pp.C.float 1.);
     B.Test.create ~name:"MakeRandom(X256pp.Int).float" (fun () ->
         Random_X256pp_Int.float 1.);
     B.Test.create ~name:"MakeRandom(X256pp.Int64).float" (fun () ->
         Random_X256pp_Int64.float 1.);
-    B.Test.create ~name:"MakeRandom(X256pp.C).float" (fun () ->
-        Random_X256pp_C.float 1.);
   ]
 
 let int64 () =
@@ -47,8 +38,6 @@ let int64 () =
         Random_X256pp_Int.int64 Int64.max_int);
     B.Test.create ~name:"MakeRandom(X256pp.Int64).int64" (fun () ->
         Random_X256pp_Int64.int64 Int64.max_int);
-    B.Test.create ~name:"MakeRandom(X256pp.C).int64" (fun () ->
-        Random_X256pp_C.int64 Int64.max_int);
   ]
 
 let () =
diff --git a/prng/src/splitmix/dune b/prng/src/splitmix/dune
index a314c11..72ad3ae 100644
--- a/prng/src/splitmix/dune
+++ b/prng/src/splitmix/dune
@@ -1,10 +1,3 @@
 (library
  (name splitmix)
- (foreign_archives splitmix)
- (foreign_stubs (language c) (names stubs))
  (libraries makeRandom))
-
-(foreign_library
- (archive_name splitmix)
- (language c)
- (names reference))
diff --git a/prng/src/splitmix/reference.ml b/prng/src/splitmix/reference.ml
deleted file mode 100644
index 79543d1..0000000
--- a/prng/src/splitmix/reference.ml
+++ /dev/null
@@ -1,2 +0,0 @@
-external seed: int64 -> unit = "caml_sm64_seed"
-external next: unit -> int64 = "caml_sm64_next"
diff --git a/prng/src/splitmix/stubs.c b/prng/src/splitmix/stubs.c
deleted file mode 100644
index d03b481..0000000
--- a/prng/src/splitmix/stubs.c
+++ /dev/null
@@ -1,24 +0,0 @@
-#include <stdint.h>
-#include "reference.h"
-
-#define CAML_NAME_SPACE
-#include <caml/mlvalues.h>
-#include <caml/memory.h>
-#include <caml/alloc.h>
-
-value caml_sm64_seed(value seed) {
-  CAMLparam1(seed);
-  int64_t x = Int64_val(seed);
-  // reinterpret x as an unsigned integer
-  sm64_seed(*(uint64_t*)(&x));
-  CAMLreturn(Val_unit);
-}
-
-value caml_sm64_next(value unit) {
-  CAMLparam1(unit);
-  uint64_t x = sm64_next();
-  // reinterpret x as a signed integer
-  value res = caml_copy_int64(*(int64_t*)(&x));
-  CAMLreturn(res);
-}
-
diff --git a/prng/src/splitmix/tests/dune b/prng/src/splitmix/tests/dune
index 0b7f5c0..f60baad 100644
--- a/prng/src/splitmix/tests/dune
+++ b/prng/src/splitmix/tests/dune
@@ -4,7 +4,7 @@
 
 (rule
  (target sm64_c.exe)
- (deps sm64_c.c ../../testutils/libtestutils.a ../libsplitmix.a)
+ (deps sm64_c.c reference.c ../../testutils/libtestutils.a)
  (action
   (run cc -Wall -Wextra -Wpedantic -o %{target} %{deps})))
 
diff --git a/prng/src/splitmix/reference.c b/prng/src/splitmix/tests/reference.c
similarity index 53%
rename from prng/src/splitmix/reference.c
rename to prng/src/splitmix/tests/reference.c
index f9897ff..18450d3 100644
--- a/prng/src/splitmix/reference.c
+++ b/prng/src/splitmix/tests/reference.c
@@ -2,20 +2,15 @@
 
 #include <stdint.h>
 
-uint64_t sm64_next_stateless(uint64_t* s) {
-	uint64_t z = (*s += 0x9e3779b97f4a7c15);
-	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
-	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
-	return z ^ (z >> 31);
-}
-
-static uint64_t state; /* The state can be seeded with any value. */
+static uint64_t s; /* The state can be seeded with any value. */
 
 void sm64_seed(uint64_t seed) {
-  state = seed;
+  s = seed;
 }
 
 uint64_t sm64_next() {
-  return sm64_next_stateless(&state);
+	uint64_t z = (s += 0x9e3779b97f4a7c15);
+	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
+	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
+	return z ^ (z >> 31);
 }
-
diff --git a/prng/src/splitmix/reference.h b/prng/src/splitmix/tests/reference.h
similarity index 73%
rename from prng/src/splitmix/reference.h
rename to prng/src/splitmix/tests/reference.h
index 311677c..ff5442c 100644
--- a/prng/src/splitmix/reference.h
+++ b/prng/src/splitmix/tests/reference.h
@@ -3,10 +3,7 @@
 
 #include <stdint.h>
 
-uint64_t sm64_next_stateless(uint64_t*);
-
 void sm64_seed(uint64_t);
 uint64_t sm64_next();
 
 #endif
-
diff --git a/prng/src/splitmix/tests/sm64_c.c b/prng/src/splitmix/tests/sm64_c.c
index 57d89e2..da4338a 100644
--- a/prng/src/splitmix/tests/sm64_c.c
+++ b/prng/src/splitmix/tests/sm64_c.c
@@ -1,9 +1,4 @@
-#include <stdio.h>
-#include <stdint.h>
-#include <stdlib.h>
-#include <getopt.h>
-
-#include "../reference.h"
+#include "reference.h"
 #include "../../testutils/testutils.h"
 
 int main(int argc, char* argv[]) {
diff --git a/prng/src/xoshiro/dune b/prng/src/xoshiro/dune
index ef6506c..fa217cc 100644
--- a/prng/src/xoshiro/dune
+++ b/prng/src/xoshiro/dune
@@ -1,10 +1,3 @@
 (library
  (name xoshiro)
- (foreign_archives xoshiro)
- (foreign_stubs (language c) (names stubs)))
-
-(foreign_library
- (archive_name xoshiro)
- (language c)
- (flags -lsplitmix)
- (names reference))
+ (libraries splitmix))
diff --git a/prng/src/xoshiro/reference.ml b/prng/src/xoshiro/reference.ml
deleted file mode 100644
index ee7ef1e..0000000
--- a/prng/src/xoshiro/reference.ml
+++ /dev/null
@@ -1,2 +0,0 @@
-external seed: int64 -> unit = "caml_x256pp_seed"
-external next: unit -> int64 = "caml_x256pp_next"
diff --git a/prng/src/xoshiro/stubs.c b/prng/src/xoshiro/stubs.c
deleted file mode 100644
index ab46b1a..0000000
--- a/prng/src/xoshiro/stubs.c
+++ /dev/null
@@ -1,42 +0,0 @@
-#define CAML_NAME_SPACE
-#include <caml/mlvalues.h>
-#include <caml/memory.h>
-#include <caml/alloc.h>
-#include <stdint.h>
-#include "reference.h"
-
-value caml_x256pp_seed(value seed) {
-  CAMLparam1(seed);
-  int64_t x = Int64_val(seed);
-  // reinterpret x as an unsigned integer
-  x256pp_seed(*(uint64_t*)(&x));
-  CAMLreturn(Val_unit);
-}
-
-value caml_x256pp_next(value unit) {
-  CAMLparam1(unit);
-  uint64_t x = x256pp_next();
-  // reinterpret x as a signed integer
-  value res = caml_copy_int64(*(int64_t*)(&x));
-  CAMLreturn(res);
-}
-
-value caml_x256pp_bits(value unit) {
-  CAMLparam1(unit);
-  intnat res = x256pp_next() >> 34;
-  CAMLreturn(Val_long(res));
-}
-
-value caml_x256pp_bits62(value unit) {
-  CAMLparam1(unit);
-  long res = x256pp_next() >> 2;
-  CAMLreturn(Val_long(res));
-}
-
-value caml_x256pp_double(value f) {
-  CAMLparam1(f);
-  double res = (x256pp_next() >> 11) * 0x1.0p-53;
-  res *= Double_val(f);
-  CAMLreturn(caml_copy_double(res));
-}
-
diff --git a/prng/src/xoshiro/tests/dune b/prng/src/xoshiro/tests/dune
index b7aba12..6a9ddd5 100644
--- a/prng/src/xoshiro/tests/dune
+++ b/prng/src/xoshiro/tests/dune
@@ -1,3 +1,17 @@
-(tests
+(executables
  (names int64 int)
- (libraries splitmix xoshiro))
+ (libraries xoshiro testutils splitmix))
+
+(rule
+ (target x256pp_c.exe)
+ (deps x256pp_c.c reference.c ../../testutils/libtestutils.a)
+ (action
+  (run cc -Wall -Wextra -Wpedantic -o %{target} %{deps})))
+
+
+(rule (with-stdout-to x256pp_int.output   (run ./int.exe      --nb=1000)))
+(rule (with-stdout-to x256pp_int64.output (run ./int64.exe    --nb=1000)))
+(rule (with-stdout-to x256pp_c.output     (run ./x256pp_c.exe --nb=1000)))
+
+(rule (alias runtest) (action (diff x256pp_int.output   x256pp_c.output)))
+(rule (alias runtest) (action (diff x256pp_int64.output x256pp_c.output)))
diff --git a/prng/src/xoshiro/tests/int.ml b/prng/src/xoshiro/tests/int.ml
index 52460b0..dbe2568 100644
--- a/prng/src/xoshiro/tests/int.ml
+++ b/prng/src/xoshiro/tests/int.ml
@@ -10,11 +10,6 @@ let int64_to_int_int n =
   let lo = to_int (logand n 0xFFFFFFFFL) in
   (hi, lo)
 
-let test_compare nb f g =
-  for _ = 1 to nb do
-    assert (f () = g ())
-  done
-
 let ocaml_seed seed =
   let s = ref seed in
   for i = 0 to 3 do
@@ -24,13 +19,6 @@ let ocaml_seed seed =
   done
 
 let () =
-  (* Chosen by fair dice rool. Guaranted to be random. *)
-  (* https://xkcd.com/221/ *)
-  let seed = 0xc6bb1e08d1a33f2fL in
-  Reference.seed seed;
-  ocaml_seed seed;
-  test_compare
-    1_000_000
-    Reference.next
-    (fun () ->
-      X256pp.Int.next () |> int_int_to_int64)
+  Testutils.run
+    ~seed_f:ocaml_seed
+    ~next:(fun () -> X256pp.Int.next () |> int_int_to_int64)
diff --git a/prng/src/xoshiro/tests/int64.ml b/prng/src/xoshiro/tests/int64.ml
index 4a9a9de..cf247e8 100644
--- a/prng/src/xoshiro/tests/int64.ml
+++ b/prng/src/xoshiro/tests/int64.ml
@@ -1,20 +1,10 @@
 open Xoshiro
 
-let test_compare nb f g =
-  for _ = 1 to nb do
-    assert (f () = g ())
-  done
-
-let ocaml_seed seed =
-  let s = ref seed in
-  for i = 0 to 3 do
-    X256pp.Int64.s.(i) <- Splitmix.Sm64.next s
-  done
-
 let () =
-  (* Chosen by fair dice rool. Guaranted to be random. *)
-  (* https://xkcd.com/221/ *)
-  let seed = 0xc6bb1e08d1a33f2fL in
-  Reference.seed seed;
-  ocaml_seed seed;
-  test_compare 1_000_000 Reference.next X256pp.Int64.next
+  Testutils.run
+    ~seed_f:(fun seed ->
+      let s = ref seed in
+      for i = 0 to 3 do
+        X256pp.Int64.s.(i) <- Splitmix.Sm64.next s
+      done)
+    ~next:X256pp.Int64.next
diff --git a/prng/src/xoshiro/reference.c b/prng/src/xoshiro/tests/reference.c
similarity index 80%
rename from prng/src/xoshiro/reference.c
rename to prng/src/xoshiro/tests/reference.c
index 6811f84..0b7c4ed 100644
--- a/prng/src/xoshiro/reference.c
+++ b/prng/src/xoshiro/tests/reference.c
@@ -1,7 +1,6 @@
 // Reference:  http://prng.di.unimi.it/xoshiro256plusplus.c
 
 #include <stdint.h>
-#include "../splitmix/reference.h"
 
 static inline uint64_t rotl(const uint64_t x, int k) {
 	return (x << k) | (x >> (64 - k));
@@ -31,6 +30,13 @@ uint64_t x256pp_next(void) {
 	return result;
 }
 
+static uint64_t sm64_next_stateless(uint64_t* s) {
+	uint64_t z = (*s += 0x9e3779b97f4a7c15);
+	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
+	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
+	return z ^ (z >> 31);
+}
+
 void x256pp_seed(uint64_t seed) {
   uint64_t s = seed;
   for (int i = 0; i < 4; i++)
diff --git a/prng/src/xoshiro/reference.h b/prng/src/xoshiro/tests/reference.h
similarity index 100%
rename from prng/src/xoshiro/reference.h
rename to prng/src/xoshiro/tests/reference.h
diff --git a/prng/src/xoshiro/tests/x256pp_c.c b/prng/src/xoshiro/tests/x256pp_c.c
new file mode 100644
index 0000000..02b2206
--- /dev/null
+++ b/prng/src/xoshiro/tests/x256pp_c.c
@@ -0,0 +1,6 @@
+#include "reference.h"
+#include "../../testutils/testutils.h"
+
+int main(int argc, char* argv[]) {
+  return testutils_run(argc, argv, x256pp_seed, x256pp_next);
+}
diff --git a/prng/src/xoshiro/x256pp.ml b/prng/src/xoshiro/x256pp.ml
index cd69cf7..23dbaca 100644
--- a/prng/src/xoshiro/x256pp.ml
+++ b/prng/src/xoshiro/x256pp.ml
@@ -162,9 +162,3 @@ module Int64 = struct
   let float x =
     Int64.(to_float (shift_right_logical (next ()) 11)) *. 0x1.0p-53 *. x
 end
-
-module C = struct
-  external bits: unit -> int = "caml_x256pp_bits"
-  external bits62: unit -> int = "caml_x256pp_bits62"
-  external float: float -> float = "caml_x256pp_double"
-end

From 822a6e8ece20701d0e111e45b4a9a2dcd0a74ed3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Mon, 18 May 2020 18:05:04 +0200
Subject: [PATCH 21/26] "True" reference implementations

---
 prng/src/splitmix/tests/dune        |  4 +-
 prng/src/splitmix/tests/reference.c | 31 ++++++++++----
 prng/src/splitmix/tests/reference.h |  4 +-
 prng/src/splitmix/tests/sm64_c.c    |  6 +--
 prng/src/xoshiro/tests/dune         |  4 +-
 prng/src/xoshiro/tests/reference.c  | 65 +++++++++++++++++++----------
 prng/src/xoshiro/tests/reference.h  |  4 +-
 prng/src/xoshiro/tests/x256pp_c.c   |  6 +--
 8 files changed, 80 insertions(+), 44 deletions(-)

diff --git a/prng/src/splitmix/tests/dune b/prng/src/splitmix/tests/dune
index f60baad..5c98517 100644
--- a/prng/src/splitmix/tests/dune
+++ b/prng/src/splitmix/tests/dune
@@ -4,9 +4,9 @@
 
 (rule
  (target sm64_c.exe)
- (deps sm64_c.c reference.c ../../testutils/libtestutils.a)
+ (deps reference.h (:codedeps sm64_c.c reference.c ../../testutils/libtestutils.a))
  (action
-  (run cc -Wall -Wextra -Wpedantic -o %{target} %{deps})))
+  (run cc -Wall -Wextra -Wpedantic -o %{target} %{codedeps})))
 
 (rule (with-stdout-to sm64_ocaml.output (run ./sm64_ocaml.exe --nb=1000)))
 (rule (with-stdout-to sm64_c.output     (run ./sm64_c.exe     --nb=1000)))
diff --git a/prng/src/splitmix/tests/reference.c b/prng/src/splitmix/tests/reference.c
index 18450d3..b99dbeb 100644
--- a/prng/src/splitmix/tests/reference.c
+++ b/prng/src/splitmix/tests/reference.c
@@ -1,16 +1,33 @@
-// Reference: http://prng.di.unimi.it/splitmix64.c
+/*  Written in 2015 by Sebastiano Vigna (vigna@acm.org)
+
+To the extent possible under law, the author has dedicated all copyright
+and related and neighboring rights to this software to the public domain
+worldwide. This software is distributed without any warranty.
+
+See <http://creativecommons.org/publicdomain/zero/1.0/>. */
 
 #include <stdint.h>
 
-static uint64_t s; /* The state can be seeded with any value. */
+/* This is a fixed-increment version of Java 8's SplittableRandom generator
+   See http://dx.doi.org/10.1145/2714064.2660195 and 
+   http://docs.oracle.com/javase/8/docs/api/java/util/SplittableRandom.html
 
-void sm64_seed(uint64_t seed) {
-  s = seed;
-}
+   It is a very fast generator passing BigCrush, and it can be useful if
+   for some reason you absolutely want 64 bits of state. */
+
+static uint64_t x; /* The state can be seeded with any value. */
 
-uint64_t sm64_next() {
-	uint64_t z = (s += 0x9e3779b97f4a7c15);
+uint64_t next() {
+	uint64_t z = (x += 0x9e3779b97f4a7c15);
 	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
 	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
 	return z ^ (z >> 31);
 }
+
+// --------------------------------
+// Above this line: verbatim copy of http://prng.di.unimi.it/splitmix64.c
+// Below: added by us for testing purpose
+
+void seed(uint64_t s) {
+  x = s;
+}
diff --git a/prng/src/splitmix/tests/reference.h b/prng/src/splitmix/tests/reference.h
index ff5442c..536a2b9 100644
--- a/prng/src/splitmix/tests/reference.h
+++ b/prng/src/splitmix/tests/reference.h
@@ -3,7 +3,7 @@
 
 #include <stdint.h>
 
-void sm64_seed(uint64_t);
-uint64_t sm64_next();
+uint64_t next();
+void seed(uint64_t);
 
 #endif
diff --git a/prng/src/splitmix/tests/sm64_c.c b/prng/src/splitmix/tests/sm64_c.c
index da4338a..24bdbb3 100644
--- a/prng/src/splitmix/tests/sm64_c.c
+++ b/prng/src/splitmix/tests/sm64_c.c
@@ -1,6 +1,6 @@
-#include "reference.h"
-#include "../../testutils/testutils.h"
+#include "reference.h" // seed, next
+#include "../../testutils/testutils.h" // testutils_run
 
 int main(int argc, char* argv[]) {
-  return testutils_run(argc, argv, sm64_seed, sm64_next);
+  return testutils_run(argc, argv, seed, next);
 }
diff --git a/prng/src/xoshiro/tests/dune b/prng/src/xoshiro/tests/dune
index 6a9ddd5..dce35c4 100644
--- a/prng/src/xoshiro/tests/dune
+++ b/prng/src/xoshiro/tests/dune
@@ -4,9 +4,9 @@
 
 (rule
  (target x256pp_c.exe)
- (deps x256pp_c.c reference.c ../../testutils/libtestutils.a)
+ (deps reference.h (:codedeps x256pp_c.c reference.c ../../testutils/libtestutils.a))
  (action
-  (run cc -Wall -Wextra -Wpedantic -o %{target} %{deps})))
+  (run cc -Wall -Wextra -Wpedantic -o %{target} %{codedeps})))
 
 
 (rule (with-stdout-to x256pp_int.output   (run ./int.exe      --nb=1000)))
diff --git a/prng/src/xoshiro/tests/reference.c b/prng/src/xoshiro/tests/reference.c
index 0b7c4ed..29d78f8 100644
--- a/prng/src/xoshiro/tests/reference.c
+++ b/prng/src/xoshiro/tests/reference.c
@@ -1,45 +1,64 @@
-// Reference:  http://prng.di.unimi.it/xoshiro256plusplus.c
+/*  Written in 2019 by David Blackman and Sebastiano Vigna (vigna@acm.org)
+
+To the extent possible under law, the author has dedicated all copyright
+and related and neighboring rights to this software to the public domain
+worldwide. This software is distributed without any warranty.
+
+See <http://creativecommons.org/publicdomain/zero/1.0/>. */
 
 #include <stdint.h>
 
+/* This is xoshiro256++ 1.0, one of our all-purpose, rock-solid generators.
+   It has excellent (sub-ns) speed, a state (256 bits) that is large
+   enough for any parallel application, and it passes all tests we are
+   aware of.
+
+   For generating just floating-point numbers, xoshiro256+ is even faster.
+
+   The state must be seeded so that it is not everywhere zero. If you have
+   a 64-bit seed, we suggest to seed a splitmix64 generator and use its
+   output to fill s. */
+
 static inline uint64_t rotl(const uint64_t x, int k) {
 	return (x << k) | (x >> (64 - k));
 }
 
-static uint64_t x256pp_state[4] = {
-  0xd430ebc2f4d9e7b8,
-  0x44815975ddd19d52,
-  0xbb18c2b0b18d0bfe,
-  0x6c0681407295c644
-};
 
-uint64_t x256pp_next(void) {
-	const uint64_t result = rotl(x256pp_state[0] + x256pp_state[3], 23) + x256pp_state[0];
+static uint64_t s[4];
+
+uint64_t next(void) {
+	const uint64_t result = rotl(s[0] + s[3], 23) + s[0];
 
-	const uint64_t t = x256pp_state[1] << 17;
+	const uint64_t t = s[1] << 17;
 
-	x256pp_state[2] ^= x256pp_state[0];
-	x256pp_state[3] ^= x256pp_state[1];
-	x256pp_state[1] ^= x256pp_state[2];
-	x256pp_state[0] ^= x256pp_state[3];
+	s[2] ^= s[0];
+	s[3] ^= s[1];
+	s[1] ^= s[2];
+	s[0] ^= s[3];
 
-	x256pp_state[2] ^= t;
+	s[2] ^= t;
 
-	x256pp_state[3] = rotl(x256pp_state[3], 45);
+	s[3] = rotl(s[3], 45);
 
 	return result;
 }
 
-static uint64_t sm64_next_stateless(uint64_t* s) {
-	uint64_t z = (*s += 0x9e3779b97f4a7c15);
+// --------------------------------
+// Above this line: verbatim copy of http://prng.di.unimi.it/xoshiro256plusplus.c
+// without the `jump` and `long_jump` functions.
+// Below: added by us for testing purpose
+
+// Use splitmix64 to seed xoshiro as suggested by Vigna.
+uint64_t splitmix64_stateless(uint64_t* state) {
+	uint64_t z = (*state += 0x9e3779b97f4a7c15);
 	z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
 	z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
 	return z ^ (z >> 31);
 }
 
-void x256pp_seed(uint64_t seed) {
-  uint64_t s = seed;
-  for (int i = 0; i < 4; i++)
-    x256pp_state[i] = sm64_next_stateless(&s);
+void seed(uint64_t x) {
+  uint64_t splitmix_state = x;
+  for (int i = 0; i < 4; i++) {
+    s[i] = splitmix64_stateless(&splitmix_state);
+  }
 }
-
diff --git a/prng/src/xoshiro/tests/reference.h b/prng/src/xoshiro/tests/reference.h
index fe5ad8f..1995ec0 100644
--- a/prng/src/xoshiro/tests/reference.h
+++ b/prng/src/xoshiro/tests/reference.h
@@ -3,8 +3,8 @@
 
 #include <stdint.h>
 
-uint64_t x256pp_next();
-void x256pp_seed(uint64_t);
+uint64_t next();
+void seed(uint64_t);
 
 #endif
 
diff --git a/prng/src/xoshiro/tests/x256pp_c.c b/prng/src/xoshiro/tests/x256pp_c.c
index 02b2206..24bdbb3 100644
--- a/prng/src/xoshiro/tests/x256pp_c.c
+++ b/prng/src/xoshiro/tests/x256pp_c.c
@@ -1,6 +1,6 @@
-#include "reference.h"
-#include "../../testutils/testutils.h"
+#include "reference.h" // seed, next
+#include "../../testutils/testutils.h" // testutils_run
 
 int main(int argc, char* argv[]) {
-  return testutils_run(argc, argv, x256pp_seed, x256pp_next);
+  return testutils_run(argc, argv, seed, next);
 }

From ad76e7ecdfd8e792f43e952cf68fb5eee2fe4ac3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Mon, 18 May 2020 20:38:55 +0200
Subject: [PATCH 22/26] Remove old benchmark

---
 prng/src/bench.ml | 46 ----------------------------------------------
 prng/src/dune     |  4 ----
 2 files changed, 50 deletions(-)
 delete mode 100644 prng/src/bench.ml
 delete mode 100644 prng/src/dune

diff --git a/prng/src/bench.ml b/prng/src/bench.ml
deleted file mode 100644
index 2177d43..0000000
--- a/prng/src/bench.ml
+++ /dev/null
@@ -1,46 +0,0 @@
-open Xoshiro
-module B = Core_bench.Bench
-module Command = Core.Command
-
-module Random_Stdlib       = MakeRandom.Basic(Random)
-module Random_X256pp_Int   = MakeRandom.Basic(X256pp.Int)
-module Random_X256pp_Int64 = MakeRandom.Basic(X256pp.Int64)
-
-let bits () =
-  Command.run @@ B.make_command [
-    B.Test.create ~name:"Random.bits" (fun () ->
-        Random.bits ());
-    B.Test.create ~name:"X256pp.Int.bits" (fun () ->
-        X256pp.Int.bits ());
-    B.Test.create ~name:"X256pp.Int64.bits" (fun () ->
-        X256pp.Int64.bits ());
-    B.Test.create ~name:"X256pp.Int64.bits62" (fun () ->
-        X256pp.Int64.bits62 ());
-  ]
-
-let float () =
-  Command.run @@ B.make_command [
-    B.Test.create ~name:"Random.float" (fun () ->
-        Random.float 1.);
-    B.Test.create ~name:"X256pp.Int64.float" (fun () ->
-        X256pp.Int64.float 1.);
-    B.Test.create ~name:"MakeRandom(X256pp.Int).float" (fun () ->
-        Random_X256pp_Int.float 1.);
-    B.Test.create ~name:"MakeRandom(X256pp.Int64).float" (fun () ->
-        Random_X256pp_Int64.float 1.);
-  ]
-
-let int64 () =
-  Command.run @@ B.make_command [
-    B.Test.create ~name:"MakeRandom(Random).int64" (fun () ->
-        Random_Stdlib.int64 Int64.max_int);
-    B.Test.create ~name:"MakeRandom(X256pp.Int).int64" (fun () ->
-        Random_X256pp_Int.int64 Int64.max_int);
-    B.Test.create ~name:"MakeRandom(X256pp.Int64).int64" (fun () ->
-        Random_X256pp_Int64.int64 Int64.max_int);
-  ]
-
-let () =
-  bits ();
-  float ();
-  int64 ()
diff --git a/prng/src/dune b/prng/src/dune
deleted file mode 100644
index 094d9f8..0000000
--- a/prng/src/dune
+++ /dev/null
@@ -1,4 +0,0 @@
-(executable
- (name bench)
- (libraries xoshiro makeRandom core_bench)
- (modules Bench))

From f873f3ea49b3717d01d2bb58da855f8f5b5fff2e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Mon, 18 May 2020 20:54:06 +0200
Subject: [PATCH 23/26] Arg.align is nice!

---
 prng/src/testutils/testutils.ml | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/prng/src/testutils/testutils.ml b/prng/src/testutils/testutils.ml
index 2e43091..1f1dc5f 100644
--- a/prng/src/testutils/testutils.ml
+++ b/prng/src/testutils/testutils.ml
@@ -6,13 +6,14 @@ let run ~seed_f ~next =
     (
       "--nb",
       Arg.Set_int nb_iterations,
-      " Number of random integers to generate"
+      "Number of random integers to generate"
     );
     (
       "--seed",
       Arg.String (fun n -> seed := Int64.of_string n),
-      " 64-bit seed");
-  ] in
+      "64-bit seed");
+  ] |> Arg.align
+  in
 
   let usage =
     Format.sprintf "%s [--seed=SEED] [--nb=N]" Sys.argv.(0)

From 0e6951b2554c061441185ca530f7946109dcc763 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Sun, 24 May 2020 17:30:20 +0200
Subject: [PATCH 24/26] Cleaner dune files

---
 dune                         | 2 ++
 prng/src/splitmix/tests/dune | 4 ++--
 prng/src/testutils/dune      | 1 -
 prng/src/xoshiro/tests/dune  | 4 ++--
 4 files changed, 6 insertions(+), 5 deletions(-)
 create mode 100644 dune

diff --git a/dune b/dune
new file mode 100644
index 0000000..11d8778
--- /dev/null
+++ b/dune
@@ -0,0 +1,2 @@
+(env
+ (_ (c_flags :standard -Wall -Werror -Wpedantic)))
diff --git a/prng/src/splitmix/tests/dune b/prng/src/splitmix/tests/dune
index 5c98517..58d28fa 100644
--- a/prng/src/splitmix/tests/dune
+++ b/prng/src/splitmix/tests/dune
@@ -4,9 +4,9 @@
 
 (rule
  (target sm64_c.exe)
- (deps reference.h (:codedeps sm64_c.c reference.c ../../testutils/libtestutils.a))
+ (deps reference.h (:codedeps sm64_c.c reference.c %{lib-private:testutils:libtestutils.a}))
  (action
-  (run cc -Wall -Wextra -Wpedantic -o %{target} %{codedeps})))
+  (run %{cc} -o %{target} %{codedeps})))
 
 (rule (with-stdout-to sm64_ocaml.output (run ./sm64_ocaml.exe --nb=1000)))
 (rule (with-stdout-to sm64_c.output     (run ./sm64_c.exe     --nb=1000)))
diff --git a/prng/src/testutils/dune b/prng/src/testutils/dune
index f7f5dce..ef7ee52 100644
--- a/prng/src/testutils/dune
+++ b/prng/src/testutils/dune
@@ -1,7 +1,6 @@
 (foreign_library
  (archive_name testutils)
  (language c)
- (flags -Wall -Wextra -Wpedantic)
  (names testutils))
 
 (library
diff --git a/prng/src/xoshiro/tests/dune b/prng/src/xoshiro/tests/dune
index dce35c4..9794944 100644
--- a/prng/src/xoshiro/tests/dune
+++ b/prng/src/xoshiro/tests/dune
@@ -4,9 +4,9 @@
 
 (rule
  (target x256pp_c.exe)
- (deps reference.h (:codedeps x256pp_c.c reference.c ../../testutils/libtestutils.a))
+ (deps reference.h (:codedeps x256pp_c.c reference.c %{lib-private:testutils:libtestutils.a}))
  (action
-  (run cc -Wall -Wextra -Wpedantic -o %{target} %{codedeps})))
+  (run %{cc} -o %{target} %{codedeps})))
 
 
 (rule (with-stdout-to x256pp_int.output   (run ./int.exe      --nb=1000)))

From 096214d93f3141c3615c963cd26dc910d33a402d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Sun, 24 May 2020 17:30:42 +0200
Subject: [PATCH 25/26] Remove some warnings

---
 testu01/testu01/bbattery_stubs.c | 11 ++++++-----
 testu01/testu01/unif01_stubs.h   |  2 --
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/testu01/testu01/bbattery_stubs.c b/testu01/testu01/bbattery_stubs.c
index acc5ab7..3e6f627 100644
--- a/testu01/testu01/bbattery_stubs.c
+++ b/testu01/testu01/bbattery_stubs.c
@@ -37,7 +37,7 @@ value caml_bbattery_SmallCrush(value bgen) {
 
 value caml_bbattery_SmallCrushFile(value filename) {
   CAMLparam1(filename);
-  bbattery_SmallCrushFile(Bytes_val(filename));
+  bbattery_SmallCrushFile((char*)Bytes_val(filename));
   CAMLreturn(Val_unit);
 }
 
@@ -97,7 +97,7 @@ value caml_bbattery_Rabbit(value bgen, value nb) {
 
 value caml_bbattery_RabbitFile(value filename, value nb) {
   CAMLparam2(filename, nb);
-  bbattery_RabbitFile (Bytes_val(filename), Double_val(nb));
+  bbattery_RabbitFile ((char*)Bytes_val(filename), Double_val(nb));
   CAMLreturn(Val_unit);
 }
 
@@ -121,7 +121,7 @@ value caml_bbattery_Alphabit(value bgen, value nb, value r, value s) {
 
 value caml_bbattery_AlphabitFile(value filename, value nb) {
   CAMLparam2(filename, nb);
-  bbattery_AlphabitFile (Bytes_val(filename), Double_val(nb));
+  bbattery_AlphabitFile ((char*)Bytes_val(filename), Double_val(nb));
   CAMLreturn(Val_unit);
 }
 
@@ -143,7 +143,7 @@ value caml_bbattery_BlockAlphabit(value bgen, value nb, value r, value s) {
 
 value caml_bbattery_BlockAlphabitFile(value filename, value nb) {
   CAMLparam2(filename, nb);
-  bbattery_BlockAlphabitFile (Bytes_val(filename), Double_val(nb));
+  bbattery_BlockAlphabitFile ((char*)Bytes_val(filename), Double_val(nb));
   CAMLreturn(Val_unit);
 }
 
@@ -156,6 +156,7 @@ value caml_bbattery_RepeatBlockAlphabit(value bgen, value nb, value r, value s,
   CAMLreturn(Val_unit);
 }
 value camlbytecode_bbattery_RepeatBlockAlphabit(value * argv, int argn) {
+  IGNORE(argn);
   return caml_bbattery_RepeatBlockAlphabit(argv[0], argv[1], argv[2], argv[3], argv[4], argv[5]);
 }
 
@@ -179,6 +180,6 @@ value caml_bbattery_FIPS_140_2(value bgen) {
 
 value caml_bbattery_FIPS_140_2File(value filename) {
   CAMLparam1(filename);
-  bbattery_FIPS_140_2File(Bytes_val(filename));
+  bbattery_FIPS_140_2File((char*)Bytes_val(filename));
   CAMLreturn(Val_unit);
 }
diff --git a/testu01/testu01/unif01_stubs.h b/testu01/testu01/unif01_stubs.h
index 09e07a0..91af9f7 100644
--- a/testu01/testu01/unif01_stubs.h
+++ b/testu01/testu01/unif01_stubs.h
@@ -12,8 +12,6 @@
 
 #include <unif01.h>
 
-static struct custom_operations unif01_Gen_boxed;
-
 #define IGNORE(x) (void)(x)
 #define unif01_Gen_unbox(bgen) (* (unif01_Gen**) Data_custom_val(bgen))
 

From 2e264aad72e776d4080696962af4c7992583de6c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20P=C3=A9pin?= <kerl@wkerl.me>
Date: Sun, 24 May 2020 17:40:18 +0200
Subject: [PATCH 26/26] More C compiler warnings

---
 dune | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dune b/dune
index 11d8778..75bd9a5 100644
--- a/dune
+++ b/dune
@@ -1,2 +1,2 @@
 (env
- (_ (c_flags :standard -Wall -Werror -Wpedantic)))
+ (_ (c_flags :standard -Werror -Wall -Wextra -pedantic)))