From e1b83f5bc69359d658fc1eb78aa2f01a9ac5ee02 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Silva?= <jgc3silva@gmail.com>
Date: Mon, 20 May 2024 13:41:39 +0100
Subject: [PATCH] Use x XOR 255 to achieve 255-x to make it faster
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: João Silva <jgc3silva@gmail.com>
---
 configure.ac                      |  4 +--
 src/random/src/scramble.avx.c     | 32 ++++++++++-----------
 src/random/src/scramble.avx512f.c | 48 +++++++++++++++++--------------
 src/random/src/scramble.c         | 16 +++++------
 src/random/src/scramble.sse.c     | 23 +++++++--------
 5 files changed, 62 insertions(+), 61 deletions(-)

diff --git a/configure.ac b/configure.ac
index d9c3e714f..225fbd96d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -184,7 +184,7 @@ else
         AX_EXT
 
         if [ test "$ax_cv_have_avx512bw_ext" = yes ]; then
-            # AVX512 extensions
+            # AVX512-BW extensions
             MLIBS_DOTPROD="src/dotprod/src/dotprod_cccf.avx512f.o \
                            src/dotprod/src/dotprod_crcf.avx512f.o \
                            src/dotprod/src/dotprod_rrrf.avx512f.o \
@@ -200,7 +200,7 @@ else
              MLIBS_RANDOM="src/random/src/scramble.avx512f.o"
             ARCH_OPTION='-mavx512bw'
         elif [ test "$ax_cv_have_avx512f_ext" = yes ]; then
-            # AVX512 extensions
+            # AVX512-F extensions
             MLIBS_DOTPROD="src/dotprod/src/dotprod_cccf.avx512f.o \
                            src/dotprod/src/dotprod_crcf.avx512f.o \
                            src/dotprod/src/dotprod_rrrf.avx512f.o \
diff --git a/src/random/src/scramble.avx.c b/src/random/src/scramble.avx.c
index eb7d1191a..f990d5a04 100644
--- a/src/random/src/scramble.avx.c
+++ b/src/random/src/scramble.avx.c
@@ -79,12 +79,10 @@ void unscramble_data(unsigned char * _x,
 void unscramble_data_soft(unsigned char * _x,
                           unsigned int _n)
 {
-#if HAVE_AVX2
     // t = 4*(floor(_n/4))
     unsigned int t = (_n >> 2) << 2;
 
     __m256i x;
-    __m256i y;
     __m256i mask = _mm256_set_epi8((LIQUID_SCRAMBLE_MASK3 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x08) ? 0xFF : 0,
                                    (LIQUID_SCRAMBLE_MASK3 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x80) ? 0xFF : 0,
                                    (LIQUID_SCRAMBLE_MASK2 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x08) ? 0xFF : 0,
@@ -98,17 +96,17 @@ void unscramble_data_soft(unsigned char * _x,
     unsigned int i;
     for (i=0; i<t; i+=4) {
         x = _mm256_lddqu_si256((const __m256i_u *)&_x[8 * i]);
-        y = _mm256_sub_epi8(mask, x);
-        x = _mm256_blendv_epi8(x, y, mask);
+
+#if HAVE_AVX2
+        x = _mm256_xor_si256(x, mask);
+#else
+        x = (__m256i)_mm256_xor_pd((__m256d)x, (__m256d)mask); // Same effect as _mm256_xor_si256, but maybe higher latency
+#endif
+
         _mm256_storeu_si256((__m256i_u *)&_x[8 * i], x);
     }
 
     for (; i<_n; i++) {
-#else
-    // apply static masks
-    unsigned int i;
-    for (i=0; i<_n; i++) {
-#endif
         unsigned char mask;
 
         switch ( i % 4 ) {
@@ -119,14 +117,14 @@ void unscramble_data_soft(unsigned char * _x,
         default:;
         }
 
-        if ( mask & 0x80 ) _x[8*i+0] = 255 - _x[8*i+0];
-        if ( mask & 0x40 ) _x[8*i+1] = 255 - _x[8*i+1];
-        if ( mask & 0x20 ) _x[8*i+2] = 255 - _x[8*i+2];
-        if ( mask & 0x10 ) _x[8*i+3] = 255 - _x[8*i+3];
-        if ( mask & 0x08 ) _x[8*i+4] = 255 - _x[8*i+4];
-        if ( mask & 0x04 ) _x[8*i+5] = 255 - _x[8*i+5];
-        if ( mask & 0x02 ) _x[8*i+6] = 255 - _x[8*i+6];
-        if ( mask & 0x01 ) _x[8*i+7] = 255 - _x[8*i+7];
+        if ( mask & 0x80 ) _x[8*i+0] ^= 255;
+        if ( mask & 0x40 ) _x[8*i+1] ^= 255;
+        if ( mask & 0x20 ) _x[8*i+2] ^= 255;
+        if ( mask & 0x10 ) _x[8*i+3] ^= 255;
+        if ( mask & 0x08 ) _x[8*i+4] ^= 255;
+        if ( mask & 0x04 ) _x[8*i+5] ^= 255;
+        if ( mask & 0x02 ) _x[8*i+6] ^= 255;
+        if ( mask & 0x01 ) _x[8*i+7] ^= 255;
     }
 }
 
diff --git a/src/random/src/scramble.avx512f.c b/src/random/src/scramble.avx512f.c
index 507764513..b440353cf 100644
--- a/src/random/src/scramble.avx512f.c
+++ b/src/random/src/scramble.avx512f.c
@@ -83,32 +83,38 @@ void unscramble_data(unsigned char * _x,
 void unscramble_data_soft(unsigned char * _x,
                           unsigned int _n)
 {
-#if HAVE_AVX512_BW
     // t = 8*(floor(_n/8))
     unsigned int t = (_n >> 3) << 3;
 
     __m512i x;
-    __mmask64 mask = ((__mmask64)liquid_reverse_byte_gentab[LIQUID_SCRAMBLE_MASK3] << 24) |
-                     ((__mmask64)liquid_reverse_byte_gentab[LIQUID_SCRAMBLE_MASK2] << 16) |
-                     ((__mmask64)liquid_reverse_byte_gentab[LIQUID_SCRAMBLE_MASK1] <<  8) |
-                     (__mmask64)(liquid_reverse_byte_gentab[LIQUID_SCRAMBLE_MASK0] <<  0);
-    mask |= (mask << 32);
-    __m512i max = _mm512_set1_epi8(255);
+    __m512i mask = _mm512_set_epi8((LIQUID_SCRAMBLE_MASK3 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x08) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK3 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x80) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK2 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x08) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK2 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x80) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK1 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x08) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK1 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x80) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK0 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x08) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK0 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x80) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK3 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x08) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK3 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK3 & 0x80) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK2 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x08) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK2 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK2 & 0x80) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK1 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x08) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK1 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x80) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK0 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x08) ? 0xFF : 0,
+                                   (LIQUID_SCRAMBLE_MASK0 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x80) ? 0xFF : 0);
 
     // apply static masks
     unsigned int i;
     for (i=0; i<t; i+=8) {
         x = _mm512_loadu_si512((const __m512i_u *)&_x[8 * i]);
-        x = _mm512_mask_sub_epi8(x, mask, max, x);
+
+        x = _mm512_xor_si512(x, mask);
+
         _mm512_storeu_si512((__m512i_u *)&_x[8 * i], x);
     }
 
     for (; i<_n; i++) {
-#else
-    // apply static masks
-    unsigned int i;
-    for (i=0; i<_n; i++) {
-#endif
         unsigned char mask;
 
         switch ( i % 4 ) {
@@ -119,14 +125,14 @@ void unscramble_data_soft(unsigned char * _x,
         default:;
         }
 
-        if ( mask & 0x80 ) _x[8*i+0] = 255 - _x[8*i+0];
-        if ( mask & 0x40 ) _x[8*i+1] = 255 - _x[8*i+1];
-        if ( mask & 0x20 ) _x[8*i+2] = 255 - _x[8*i+2];
-        if ( mask & 0x10 ) _x[8*i+3] = 255 - _x[8*i+3];
-        if ( mask & 0x08 ) _x[8*i+4] = 255 - _x[8*i+4];
-        if ( mask & 0x04 ) _x[8*i+5] = 255 - _x[8*i+5];
-        if ( mask & 0x02 ) _x[8*i+6] = 255 - _x[8*i+6];
-        if ( mask & 0x01 ) _x[8*i+7] = 255 - _x[8*i+7];
+        if ( mask & 0x80 ) _x[8*i+0] ^= 255;
+        if ( mask & 0x40 ) _x[8*i+1] ^= 255;
+        if ( mask & 0x20 ) _x[8*i+2] ^= 255;
+        if ( mask & 0x10 ) _x[8*i+3] ^= 255;
+        if ( mask & 0x08 ) _x[8*i+4] ^= 255;
+        if ( mask & 0x04 ) _x[8*i+5] ^= 255;
+        if ( mask & 0x02 ) _x[8*i+6] ^= 255;
+        if ( mask & 0x01 ) _x[8*i+7] ^= 255;
     }
 }
 
diff --git a/src/random/src/scramble.c b/src/random/src/scramble.c
index 52f576d28..804696e75 100644
--- a/src/random/src/scramble.c
+++ b/src/random/src/scramble.c
@@ -86,14 +86,14 @@ void unscramble_data_soft(unsigned char * _x,
                 _x[8*i+j] = 255 - _x[8*i+j];
         }
 #else
-        if ( mask & 0x80 ) _x[8*i+0] = 255 - _x[8*i+0];
-        if ( mask & 0x40 ) _x[8*i+1] = 255 - _x[8*i+1];
-        if ( mask & 0x20 ) _x[8*i+2] = 255 - _x[8*i+2];
-        if ( mask & 0x10 ) _x[8*i+3] = 255 - _x[8*i+3];
-        if ( mask & 0x08 ) _x[8*i+4] = 255 - _x[8*i+4];
-        if ( mask & 0x04 ) _x[8*i+5] = 255 - _x[8*i+5];
-        if ( mask & 0x02 ) _x[8*i+6] = 255 - _x[8*i+6];
-        if ( mask & 0x01 ) _x[8*i+7] = 255 - _x[8*i+7];
+        if ( mask & 0x80 ) _x[8*i+0] ^= 255;
+        if ( mask & 0x40 ) _x[8*i+1] ^= 255;
+        if ( mask & 0x20 ) _x[8*i+2] ^= 255;
+        if ( mask & 0x10 ) _x[8*i+3] ^= 255;
+        if ( mask & 0x08 ) _x[8*i+4] ^= 255;
+        if ( mask & 0x04 ) _x[8*i+5] ^= 255;
+        if ( mask & 0x02 ) _x[8*i+6] ^= 255;
+        if ( mask & 0x01 ) _x[8*i+7] ^= 255;
 #endif
     }
 }
diff --git a/src/random/src/scramble.sse.c b/src/random/src/scramble.sse.c
index 75dcc9817..ccbf8430c 100644
--- a/src/random/src/scramble.sse.c
+++ b/src/random/src/scramble.sse.c
@@ -83,7 +83,6 @@ void unscramble_data_soft(unsigned char * _x,
     unsigned int t = (_n >> 2) << 2;
 
     __m128i x;
-    __m128i y;
     __m128i mask01 = _mm_set_epi8((LIQUID_SCRAMBLE_MASK1 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x08) ? 0xFF : 0,
                                   (LIQUID_SCRAMBLE_MASK1 & 0x10) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x20) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x40) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK1 & 0x80) ? 0xFF : 0,
                                   (LIQUID_SCRAMBLE_MASK0 & 0x01) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x02) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x04) ? 0xFF : 0, (LIQUID_SCRAMBLE_MASK0 & 0x08) ? 0xFF : 0,
@@ -97,13 +96,11 @@ void unscramble_data_soft(unsigned char * _x,
     unsigned int i;
     for (i=0; i<t; i+=4) {
         x = _mm_lddqu_si128((const __m128i_u *)&_x[8 * i]);
-        y = _mm_sub_epi8(mask01, x);
-        x = _mm_blendv_epi8(x, y, mask01);
+        x = _mm_xor_si128(x, mask01);
         _mm_storeu_si128((__m128i_u *)&_x[8 * i], x);
 
         x = _mm_lddqu_si128((const __m128i_u *)&_x[8 * i + 16]);
-        y = _mm_sub_epi8(mask23, x);
-        x = _mm_blendv_epi8(x, y, mask23);
+        x = _mm_xor_si128(x, mask23);
         _mm_storeu_si128((__m128i_u *)&_x[8 * i + 16], x);
     }
 
@@ -123,14 +120,14 @@ void unscramble_data_soft(unsigned char * _x,
         default:;
         }
 
-        if ( mask & 0x80 ) _x[8*i+0] = 255 - _x[8*i+0];
-        if ( mask & 0x40 ) _x[8*i+1] = 255 - _x[8*i+1];
-        if ( mask & 0x20 ) _x[8*i+2] = 255 - _x[8*i+2];
-        if ( mask & 0x10 ) _x[8*i+3] = 255 - _x[8*i+3];
-        if ( mask & 0x08 ) _x[8*i+4] = 255 - _x[8*i+4];
-        if ( mask & 0x04 ) _x[8*i+5] = 255 - _x[8*i+5];
-        if ( mask & 0x02 ) _x[8*i+6] = 255 - _x[8*i+6];
-        if ( mask & 0x01 ) _x[8*i+7] = 255 - _x[8*i+7];
+        if ( mask & 0x80 ) _x[8*i+0] ^= 255;
+        if ( mask & 0x40 ) _x[8*i+1] ^= 255;
+        if ( mask & 0x20 ) _x[8*i+2] ^= 255;
+        if ( mask & 0x10 ) _x[8*i+3] ^= 255;
+        if ( mask & 0x08 ) _x[8*i+4] ^= 255;
+        if ( mask & 0x04 ) _x[8*i+5] ^= 255;
+        if ( mask & 0x02 ) _x[8*i+6] ^= 255;
+        if ( mask & 0x01 ) _x[8*i+7] ^= 255;
     }
 }