From cfaf26a230567748ac3ea2b52080ac87fdb17b1d Mon Sep 17 00:00:00 2001
From: travisstaloch <twostepted@gmail.com>
Date: Tue, 22 Aug 2023 16:59:46 -0700
Subject: [PATCH] use lookup table in alphaIdx() (#1)

---
 ulid.zig | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/ulid.zig b/ulid.zig
index 4f30cee..a33d252 100644
--- a/ulid.zig
+++ b/ulid.zig
@@ -12,6 +12,15 @@ const text_time_bytes = 10;
 const text_rand_bytes = 16;
 
 fn alphaIdx(c: u8) ?u8 {
+    const alpha_idxs = comptime blk: {
+        var idxs = [1]?u8{null} ** 256;
+        for (0..256) |i| idxs[i] = _alphaIdx(@truncate(i));
+        break :blk idxs;
+    };
+    return alpha_idxs[c];
+}
+
+fn _alphaIdx(c: u8) ?u8 {
     return switch (c) {
         // inline 0...47 => null,
         inline '0'...'9' => |i| i - 48,