From 30740ca4131d1f574718262451b4410207dc8d4e Mon Sep 17 00:00:00 2001
From: Mitya Selivanov <automainint@guattari.tech>
Date: Sun, 14 Jul 2024 21:12:37 +0200
Subject: Reworking the build system

---
 kit/mersenne_twister_64.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 kit/mersenne_twister_64.c

(limited to 'kit/mersenne_twister_64.c')

diff --git a/kit/mersenne_twister_64.c b/kit/mersenne_twister_64.c
new file mode 100644
index 0000000..4032dc9
--- /dev/null
+++ b/kit/mersenne_twister_64.c
@@ -0,0 +1,66 @@
+#include "mersenne_twister_64.h"
+
+#define MM 156
+#define MATRIX_A 0xb5026f5aa96619e9ull
+#define UM 0xffffffff80000000ull
+#define LM 0x7fffffffull
+
+void kit_mt64_init_array(kit_mt64_state_t *state, i64 size,
+                         u64 *seed) {
+  i64 i;
+  for (i = 0; i < size && i < KIT_MT64_N; i++) state->mt[i] = seed[i];
+  for (state->index = size; state->index < KIT_MT64_N; state->index++)
+    state->mt[state->index] = (6364136223846793005ull *
+                                   (state->mt[state->index - 1] ^
+                                    (state->mt[state->index - 1] >>
+                                     62u)) +
+                               state->index);
+}
+
+void kit_mt64_init(kit_mt64_state_t *state, u64 seed) {
+  kit_mt64_init_array(state, 1, &seed);
+}
+
+void kit_mt64_rotate(kit_mt64_state_t *state) {
+  static u64 mag01[2] = { 0ull, MATRIX_A };
+
+  u64 x;
+  i32 i;
+
+  for (i = 0; i < KIT_MT64_N - MM; i++) {
+    x            = (state->mt[i] & UM) | (state->mt[i + 1] & LM);
+    state->mt[i] = state->mt[i + MM] ^ (x >> 1u) ^
+                   mag01[(i32) (x & 1ull)];
+  }
+
+  for (; i < KIT_MT64_N - 1; i++) {
+    x            = (state->mt[i] & UM) | (state->mt[i + 1] & LM);
+    state->mt[i] = state->mt[i + (MM - KIT_MT64_N)] ^ (x >> 1u) ^
+                   mag01[(i32) (x & 1ull)];
+  }
+
+  x = (state->mt[KIT_MT64_N - 1] & UM) | (state->mt[0] & LM);
+  state->mt[KIT_MT64_N - 1] = state->mt[MM - 1] ^ (x >> 1u) ^
+                              mag01[(i32) (x & 1ull)];
+
+  state->index = 0;
+}
+
+u64 kit_mt64_generate(kit_mt64_state_t *state) {
+  if (state->index >= KIT_MT64_N)
+    kit_mt64_rotate(state);
+
+  u64 x = state->mt[state->index++];
+
+  x ^= (x >> 29u) & 0x5555555555555555ull;
+  x ^= (x << 17u) & 0x71d67fffeda60000ull;
+  x ^= (x << 37u) & 0xfff7eee000000000ull;
+  x ^= (x >> 43u);
+
+  return x;
+}
+
+#undef MM
+#undef MATRIX_A
+#undef UM
+#undef LM
-- 
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