diff options
Diffstat (limited to 'rand.c')
| -rw-r--r-- | rand.c | 37 |
1 files changed, 31 insertions, 6 deletions
@@ -38,8 +38,9 @@ #include "signal.h" #include "unwind.h" #include "arith.h" -#include "rand.h" #include "eval.h" +#include "txr.h" +#include "rand.h" #define random_warmup (deref(lookup_var_l(nil, random_warmup_s))) @@ -90,7 +91,7 @@ INLINE rand32_t *rstate(struct rand_state *r, int offs) return &r->state[(r->cur + offs) % 16]; } -static rand32_t rand32(struct rand_state *r) +static rand32_t rand32_bug(struct rand_state *r) { rand32_t s0 = *rstate(r, 0); rand32_t s9 = *rstate(r, 9); @@ -109,6 +110,27 @@ static rand32_t rand32(struct rand_state *r) return ns15; } +static rand32_t rand32_good(struct rand_state *r) +{ + rand32_t s0 = *rstate(r, 0); + rand32_t s9 = *rstate(r, 9); + rand32_t s13 = *rstate(r, 13); + rand32_t s15 = *rstate(r, 15); + + rand32_t r1 = s0 ^ (s0 << 16) ^ s13 ^ (s13 << 15); + rand32_t r2 = s9 ^ (s9 >> 11); + + rand32_t ns0 = *rstate(r, 0) = r1 ^ r2; + rand32_t ns15 = s15 ^ (s15 << 2) ^ r1 ^ (r1 << 18) ^ (r2 << 28) ^ + (ns0 ^ ((ns0 << 5) & 0xDA442D24UL)); + + *rstate(r, 15) = ns15; + r->cur = (r->cur + 15) % 16; + return ns15; +} + +static rand32_t (*rand32)(struct rand_state *) = rand32_good; + val make_random_state(val seed, val warmup) { val self = lit("make-random-state"); @@ -342,11 +364,14 @@ val rnd(val modulus, val state) void rand_compat_fixup(int compat_ver) { - if (compat_ver <= 139) { + if (compat_ver <= 243) { loc l = lookup_var_l(nil, random_state_var_s); - memset(rand_tab, 0xAA, sizeof rand_tab); - if (compat_ver <= 114) - random_state_s = random_state_var_s; + if (compat_ver <= 139) { + memset(rand_tab, 0xAA, sizeof rand_tab); + if (compat_ver <= 114) + random_state_s = random_state_var_s; + } + rand32 = rand32_bug; set(l, make_random_state(num_fast(42), num_fast(8))); } } |