From ed809a51fdd1c313cd256301ef6f7211e8394cb1 Mon Sep 17 00:00:00 2001
From: David Timber <mieabby@gmail.com>
Date: Wed, 1 Jan 2020 09:50:34 +1100
Subject: checkpoint

---
 src/rnd.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 src/rnd.c

(limited to 'src/rnd.c')

diff --git a/src/rnd.c b/src/rnd.c
new file mode 100644
index 0000000..8fff675
--- /dev/null
+++ b/src/rnd.c
@@ -0,0 +1,93 @@
+#include "rnd.h"
+
+#include <stdlib.h>
+
+#define N ((size_t)624)
+
+
+struct prne_rnd_engine {
+	size_t mti;
+	uint32_t mt[N];
+};
+
+
+void prne_init_alloc_rnd_engine_result (prne_rnd_engnie_alloc_result_t *r) {
+	r->engine = NULL;
+	r->result = PRNE_RND_ENGINE_ALLOC_OK;
+}
+
+prne_rnd_engnie_alloc_result_t prne_alloc_rnd_engine (const uint32_t *s) {
+	prne_rnd_engnie_alloc_result_t ret;
+	uint32_t seed;
+
+	prne_init_alloc_rnd_engine_result(&ret);
+	
+	if (s == NULL) {
+		seed = 4357;
+	}
+	else {
+		if (*s == 0) {
+			ret.result = PRNE_RND_ENGINE_ALLOC_INVALID_SEED;
+			return ret;
+		}
+		seed = *s;
+	}
+	
+	ret.engine = (prne_rnd_engine_t*)malloc(sizeof(prne_rnd_engine_t));
+	if (ret.engine == NULL) {
+		ret.result = PRNE_RND_ENGINE_ALLOC_MEM_ERR;
+		return ret;
+	}
+
+	ret.engine->mt[0] = seed;
+	for (ret.engine->mti = 1; ret.engine->mti < N; ret.engine->mti += 1) {
+		ret.engine->mt[ret.engine->mti] = 69069 * ret.engine->mt[ret.engine->mti - 1];
+	}
+
+	return ret;
+}
+
+void prne_free_rnd_engine (prne_rnd_engine_t *engine) {
+	free(engine);
+}
+
+uint32_t prne_rnd_gen_int (prne_rnd_engine_t *engine) {
+	static const size_t M = 397;
+	static const uint32_t
+		UPPER_MASK = 0x80000000,
+		LOWER_MASK = 0x7fffffff,
+		TEMPERING_MASK_B = 0x9d2c5680,
+		TEMPERING_MASK_C = 0xefc60000;
+	static const uint32_t mag01[2] = {0, 0x9908b0df};
+	uint32_t y;
+	
+	if (engine->mti >= N) {
+		size_t kk;
+
+		for (kk = 0; kk < N - M; kk += 1) {
+			y = (engine->mt[kk] & UPPER_MASK) | (engine->mt[kk + 1] & LOWER_MASK);
+			engine->mt[kk] = engine->mt[kk + M] ^ (y >> 1) ^ mag01[y & 1];
+		}
+		for (; kk < N - 1; kk += 1) {
+			y = (engine->mt[kk] & UPPER_MASK) | (engine->mt[kk + 1] & LOWER_MASK);
+			engine->mt[kk] = engine->mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 1];
+		}
+		y = (engine->mt[N - 1] & UPPER_MASK) | (engine->mt[0] & LOWER_MASK);
+		engine->mt[N - 1] = engine->mt[M - 1] ^ (y >> 1) ^ mag01[y & 1];
+
+		engine->mti = 0;
+	}
+
+	y = engine->mt[engine->mti];
+	engine->mti += 1;
+	y ^= y >> 11;
+	y ^= (y << 7) & TEMPERING_MASK_B;
+	y ^= (y << 15) & TEMPERING_MASK_C;
+	y ^= y >> 18;
+
+	return y;
+}
+
+double prne_rnd_gen_double (prne_rnd_engine_t *engine) {
+	return (double)prne_rnd_gen_int(engine) * 2.3283064370807974e-10;
+}
-- 
cgit