- added RNG abstract random object rng_{new/free/seed/get{Int,Double,Float}}

   to avoid use of global generator. at the moment the renderer owns the
   number generator and this is important for retaining render consistency.

2 files changed, 81 insertions, 43 deletions

diff --git a/source/blender/blenlib/BLI_rand.h b/source/blender/blenlib/BLI_rand.h
index c352016ff53..5168d4b9fea 100644
--- a/source/blender/blenlib/BLI_rand.h
+++ b/source/blender/blenlib/BLI_rand.h
@@ -36,6 +36,21 @@
 #ifndef BLI_RAND_H
 #define BLI_RAND_H
 
+	/* RNG is just an abstract random number generator
+	 * type that avoids using globals, otherwise identical
+	 * to BLI_rand functions below.
+	 */
+struct RNG;
+
+struct RNG*	rng_new			(unsigned int seed);
+void		rng_free		(struct RNG* rng);
+
+void		rng_seed		(struct RNG* rng, unsigned int seed);
+int			rng_getInt		(struct RNG* rng);
+double		rng_getDouble	(struct RNG* rng);
+float		rng_getFloat	(struct RNG* rng);
+void		rng_shuffleArray(struct RNG *rng, void *data, int elemSize, int numElems);
+
 	/** Seed the random number generator */
 void	BLI_srand		(unsigned int seed);
 
@@ -55,17 +70,10 @@ float	BLI_frand		(void);
 	 */
 void	BLI_fillrand	(void *addr, int len);
 
-	/** Stores the BLI randum number generator state
-	 * into the buffer in @a loc_r.
-	 */
-void	BLI_storerand	(unsigned int loc_r[2]);
-
-	/** Retores the BLI randum number generator state
-	 * from the buffer in @a loc.
+	/** Shuffle an array randomly using the given seed.
+	 * contents. This routine does not use nor modify
+	 * the state of the BLI random number generator.
 	 */
-void	BLI_restorerand	(unsigned int loc[2]);
-
-	/** Shuffle an array randomly using the given seed. */
 void	BLI_array_randomize	(void *data, int elemSize, int numElems, unsigned int seed);
 
 #endif
diff --git a/source/blender/blenlib/intern/rand.c b/source/blender/blenlib/intern/rand.c
index 28a50a62922..ef048a5dd5e 100644
--- a/source/blender/blenlib/intern/rand.c
+++ b/source/blender/blenlib/intern/rand.c
@@ -33,6 +33,8 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "MEM_guardedalloc.h"
+
 #include "PIL_time.h"
 #include "BLI_rand.h"
 
@@ -51,57 +53,50 @@ typedef unsigned long long	r_uint64;
 
 #define LOWSEED		0x330E
 
-static r_uint64 X= 0;
+/***/
 
-void BLI_srand(unsigned int seed) {
-	X= (((r_uint64) seed)<<16) | LOWSEED;
-}
+typedef struct RNG {
+	r_uint64 X;
+} RNG;
 
-int BLI_rand(void) {
-	X= (MULTIPLIER*X + ADDEND)&0x0000FFFFFFFFFFFF;
-	return (int) (X>>17);
-}
+RNG	*rng_new(unsigned int seed)
+{
+	RNG *rng = MEM_mallocN(sizeof(*rng), "rng");
 
-double BLI_drand(void) {
-	return (double) BLI_rand()/0x80000000;
+	rng_seed(rng, seed);
+
+	return rng;
 }
 
-float BLI_frand(void) {
-	return (float) BLI_rand()/0x80000000;
+void rng_free(RNG* rng)
+{
+	MEM_freeN(rng);
 }
 
-void BLI_storerand(unsigned int loc_r[2]) {
-	loc_r[0]= (unsigned int) (X>>32);
-	loc_r[1]= (unsigned int) (X&0xFFFFFFFF);
+void rng_seed(RNG *rng, unsigned int seed) {
+	rng->X= (((r_uint64) seed)<<16) | LOWSEED;
 }
 
-void BLI_restorerand(unsigned int loc[2]) {
-	X= ((r_uint64) loc[0])<<32;
-	X|= loc[1];
+int rng_getInt(RNG *rng) {
+	rng->X= (MULTIPLIER*rng->X + ADDEND)&0x0000FFFFFFFFFFFF;
+	return (int) (rng->X>>17);
 }
 
-void BLI_fillrand(void *addr, int len) {
-	unsigned char *p= addr;
-	unsigned int save[2];
+double rng_getDouble(RNG *rng) {
+	return (double) rng_getInt(rng)/0x80000000;
+}
 
-	BLI_storerand(save);
-	
-	BLI_srand((unsigned int) (PIL_check_seconds_timer()*0x7FFFFFFF));
-	while (len--) *p++= BLI_rand()&0xFF;
-	BLI_restorerand(save);
+float rng_getFloat(RNG *rng) {
+	return (float) rng_getInt(rng)/0x80000000;
 }
 
-void BLI_array_randomize(void *data, int elemSize, int numElems, unsigned int seed)
+void rng_shuffleArray(RNG *rng, void *data, int elemSize, int numElems)
 {
-	unsigned int oldrand[2];
 	int i = numElems;
 	void *temp = malloc(elemSize);
 
-	BLI_storerand(oldrand);
-	BLI_srand(seed);
-
 	while (--i) {
-		int j = BLI_rand()%i;
+		int j = rng_getInt(rng)%i;
 		void *iElem = (unsigned char*)data + i*elemSize;
 		void *jElem = (unsigned char*)data + j*elemSize;
 
@@ -110,7 +105,42 @@ void BLI_array_randomize(void *data, int elemSize, int numElems, unsigned int se
 		memcpy(jElem, temp, elemSize);
 	}
 
-	BLI_restorerand(oldrand);
 	free(temp);
 }
 
+/***/
+
+static RNG theBLI_rng = {0};
+
+void BLI_srand(unsigned int seed) {
+	rng_seed(&theBLI_rng, seed);
+}
+
+int BLI_rand(void) {
+	return rng_getInt(&theBLI_rng);
+}
+
+double BLI_drand(void) {
+	return rng_getDouble(&theBLI_rng);
+}
+
+float BLI_frand(void) {
+	return rng_getFloat(&theBLI_rng);
+}
+
+void BLI_fillrand(void *addr, int len) {
+	RNG rng;
+	unsigned char *p= addr;
+
+	rng_seed(&rng, (unsigned int) (PIL_check_seconds_timer()*0x7FFFFFFF));
+	while (len--) *p++= rng_getInt(&rng)&0xFF;
+}
+
+void BLI_array_randomize(void *data, int elemSize, int numElems, unsigned int seed)
+{
+	RNG rng;
+
+	rng_seed(&rng, seed);
+	rng_shuffleArray(&rng, data, elemSize, numElems);
+}
+