mirror of
https://github.com/DarkPlacesEngine/gmqcc.git
synced 2024-11-23 12:22:26 +00:00
Added my awesome MT1997 PRNG, and use it instead of stdio's rand()/srand() .. which are implementation specific .. and simply unsafe (for example one of the compilers at work simply has it's standard library implementation of rand() return 0 always (which is perfectly conformant)).
This commit is contained in:
Dale Weiler
parent
0a57c408c0
commit
fa155f8a42
4 changed files with 184 additions and 7 deletions
14
ftepp.c
14
ftepp.c
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@ -77,8 +77,8 @@ typedef struct {
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* Implement the predef subsystem now. We can do this safely with the
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* help of lexer contexts.
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*/
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static int ftepp_predef_countval = 0;
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static int ftepp_predef_randval = 0;
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static uint32_t ftepp_predef_countval = 0;
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static uint32_t ftepp_predef_randval = 0;
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/* __LINE__ */
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char *ftepp_predef_line(lex_file *context) {
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@ -98,7 +98,7 @@ char *ftepp_predef_file(lex_file *context) {
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/* __COUNTER_LAST__ */
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char *ftepp_predef_counterlast(lex_file *context) {
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char *value = (char*)mem_a(128);
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sprintf(value, "%d", ftepp_predef_countval);
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sprintf(value, "%u", ftepp_predef_countval);
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(void)context;
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return value;
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@ -107,7 +107,7 @@ char *ftepp_predef_counterlast(lex_file *context) {
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char *ftepp_predef_counter(lex_file *context) {
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char *value = (char*)mem_a(128);
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ftepp_predef_countval ++;
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sprintf(value, "%d", ftepp_predef_countval);
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sprintf(value, "%u", ftepp_predef_countval);
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(void)context;
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return value;
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@ -115,8 +115,8 @@ char *ftepp_predef_counter(lex_file *context) {
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/* __RANDOM__ */
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char *ftepp_predef_random(lex_file *context) {
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char *value = (char*)mem_a(128);
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ftepp_predef_randval = rand() % 0xFFFF; /* short int */
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sprintf(value, "%d", ftepp_predef_randval);
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ftepp_predef_randval = (util_rand() % 0xFF) + 1;
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sprintf(value, "%u", ftepp_predef_randval);
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(void)context;
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return value;
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@ -124,7 +124,7 @@ char *ftepp_predef_random(lex_file *context) {
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/* __RANDOM_LAST__ */
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char *ftepp_predef_randomlast(lex_file *context) {
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char *value = (char*)mem_a(128);
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sprintf(value, "%d", ftepp_predef_randval);
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sprintf(value, "%u", ftepp_predef_randval);
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(void)context;
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return value;
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3
gmqcc.h
3
gmqcc.h
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@ -260,6 +260,9 @@ size_t util_strtononcmd (const char *, char *, size_t);
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uint16_t util_crc16(uint16_t crc, const char *data, size_t len);
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void util_seed(uint32_t);
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uint32_t util_rand();
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#ifdef NOTRACK
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# define mem_a(x) malloc (x)
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# define mem_d(x) free ((void*)x)
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3
main.c
3
main.c
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@ -23,6 +23,7 @@
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*/
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#include "gmqcc.h"
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#include "lexer.h"
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#include <time.h>
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/* TODO: cleanup this whole file .. it's a fuckign mess */
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@ -505,6 +506,8 @@ int main(int argc, char **argv) {
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con_init ();
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opts_init("progs.dat", COMPILER_GMQCC, (1024 << 3));
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util_seed(time(0));
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if (!options_parse(argc, argv)) {
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return usage();
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}
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171
util.c
171
util.c
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@ -538,3 +538,174 @@ void util_htdel(hash_table_t *ht) {
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mem_d(ht->table);
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mem_d(ht);
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}
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/*
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* Implementation of the Mersenne twister PRNG (pseudo random numer
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* generator). Implementation of MT19937. Has a period of 2^19937-1
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* which is a Mersenne Prime (hence the name).
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*
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* Implemented from specification and original paper:
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* http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/ARTICLES/mt.pdf
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*
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* This code is placed in the public domain by me personally
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* (Dale Weiler, a.k.a graphitemaster).
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*/
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#define MT_SIZE 624
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#define MT_PERIOD 397
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#define MT_SPACE (MT_SIZE - MT_PERIOD)
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static uint32_t mt_state[MT_SIZE];
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static size_t mt_index = 0;
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static GMQCC_INLINE void mt_generate() {
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/*
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* The loop has been unrolled here: the original paper and implemenation
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* Called for the following code:
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* for (register unsigned i = 0; i < MT_SIZE; ++i) {
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* register uint32_t load;
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* load = (0x80000000 & mt_state[i]) // most significant 32nd bit
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* load |= (0x7FFFFFFF & mt_state[(i + 1) % MT_SIZE]) // least significant 31nd bit
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*
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* mt_state[i] = mt_state[(i + MT_PERIOD) % MT_SIZE] ^ (load >> 1);
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*
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* if (load & 1) mt_state[i] ^= 0x9908B0DF;
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* }
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*
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* This essentially is a waste: we have two modulus operations, and
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* a branch that is executed every iteration from [0, MT_SIZE).
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*
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* Please see: http://www.quadibloc.com/crypto/co4814.htm for more
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* information on how this clever trick works.
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*/
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static const uint32_t matrix[2] = {
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0x00000000,
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0x9908B0Df
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};
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/*
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* This register gives up a little more speed by instructing the compiler
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* to force these into CPU registers (they're counters for indexing mt_state
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* which we can force the compiler to generate prefetch instructions for)
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*/
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register uint32_t y;
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register uint32_t i;
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/*
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* Said loop has been unrolled for MT_SPACE (226 iterations), opposed
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* to [0, MT_SIZE) (634 iterations).
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*/
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for (i = 0; i < MT_SPACE; ++i) {
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y = (0x800000000 & mt_state[i]) | (0x7FFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i + MT_PERIOD] ^ (y >> 1) ^ matrix[y & 1];
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i ++; /* loop unroll */
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y = (0x800000000 & mt_state[i]) | (0x7FFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i + MT_PERIOD] ^ (y >> 1) ^ matrix[y & 1];
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}
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/*
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* collapsing the walls unrolled (evenly dividing 396 [632-227 = 396
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* = 2*2*3*3*11])
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*/
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i = MT_SPACE;
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while (i < MT_SIZE - 1) {
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/*
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* We expand this 11 times .. manually, no macros are required
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* here. This all fits in the CPU cache.
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*/
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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y = (0x80000000 & mt_state[i]) | (0x7FFFFFFF & mt_state[i + 1]);
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mt_state[i] = mt_state[i - MT_SPACE] ^ (y >> 1) ^ matrix[y & 1];
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++i;
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}
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/* i = mt_state[623] */
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y = (0x80000000 & mt_state[MT_SIZE - 1]) | (0x7FFFFFFF & mt_state[MT_SIZE - 1]);
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mt_state[MT_SIZE - 1] = mt_state[MT_PERIOD - 1] ^ (y >> 1) ^ matrix[y & 1];
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}
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void util_seed(uint32_t value) {
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/*
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* We seed the mt_state with a LCG (linear congruential generator)
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* We're operating exactly on exactly m=32, so there is no need to
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* use modulus.
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*
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* The multipler of choice is 0x6C07865, also knows as the Borosh-
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* Niederreiter multipler used for modulus 2^32. More can be read
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* about this in Knuth's TAOCP Volume 2, page 106.
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*
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* If you don't own TAOCP something is wrong with you :-) .. so I
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* also provided a link to the original paper by Borosh and
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* Niederreiter. It's called "Optional Multipliers for PRNG by The
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* Linear Congruential Method" (1983).
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* http://en.wikipedia.org/wiki/Linear_congruential_generator
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*
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* From said page, it says the following:
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* "A common Mersenne twister implementation, interestingly enough
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* used an LCG to generate seed data."
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*
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* Remarks:
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* The data we're operating on is 32-bits for the mt_state array, so
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* there is no masking required with 0xFFFFFFFF
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*/
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register size_t i;
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mt_state[0] = value;
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for (i = 1; i < MT_SIZE; ++i)
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mt_state[i] = 0x6C078965 * (mt_state[i - 1] ^ mt_state[i - 1] >> 30) + i;
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}
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uint32_t util_rand() {
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register uint32_t y;
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/*
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* This is inlined with any sane compiler (I checked)
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* for some reason though, SubC seems to be generating invalid
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* code when it inlines this.
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*/
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if (!mt_index)
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mt_generate();
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y = mt_state[mt_index];
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/* Standard tempering */
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y ^= y >> 11; /* +7 */
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y ^= y << 7 & 0x9D2C5680; /* +4 */
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y ^= y << 15 & 0xEFC60000; /* -4 */
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y ^= y >> 18; /* -7 */
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if(++mt_index == MT_SIZE)
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mt_index = 0;
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return y;
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}
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