diff options
| -rw-r--r-- | libgcompat/random_r.c | 76 |
1 files changed, 39 insertions, 37 deletions
diff --git a/libgcompat/random_r.c b/libgcompat/random_r.c index daa23e7..cfc0d20 100644 --- a/libgcompat/random_r.c +++ b/libgcompat/random_r.c @@ -45,10 +45,10 @@ struct random_data { int32_t *x; /* int32_t *fptr */ int32_t *unused_1; /* int32_t *rptr */ int32_t *unused_2; /* int32_t *state */ - int n; /* int rand_type */ - int i; /* int rand_deg */ - int j; /* int rand_sep */ - int32_t *unused_3; /* int32_t *end_ptr */ + int unused_3; /* int rand_type */ + int unused_4; /* int rand_deg */ + int unused_5; /* int rand_sep */ + int32_t *unused_6; /* int32_t *end_ptr */ }; static uint32_t lcg31(uint32_t x) { @@ -59,65 +59,62 @@ static uint64_t lcg64(uint64_t x) { return 6364136223846793005ull*x + 1; } -static void savestate_r(struct random_data *buf) { - buf->x[-1] = (buf->n<<16)|(buf->i<<8)|buf->j; -} - -static void loadstate_r(uint32_t *state, struct random_data *buf) { - buf->x = (int32_t *)state + 1; - buf->n = buf->x[-1]>>16; - buf->i = (buf->x[-1]>>8)&0xff; - buf->j = buf->x[-1]&0xff; -} - int srandom_r(unsigned seed, struct random_data *buf) { int k; uint64_t s = seed; + int n, i, j; if (buf == NULL) { return -1; } - if (buf->n > 63) { + n = buf->x[-1]>>16; + i = (buf->x[-1]>>8)&0xff; + j = buf->x[-1]&0xff; + + if (n > 63) { return -1; - } else if (buf->n == 0) { + } else if (n == 0) { buf->x[0] = s; return 0; } - buf->i = buf->n == 31 || buf->n == 7 ? 3 : 1; - buf->j = 0; - for (k = 0; k < buf->n; k++) { + i = n == 31 || n == 7 ? 3 : 1; + j = 0; + for (k = 0; k < n; k++) { s = lcg64(s); buf->x[k] = s>>32; } /* make sure x contains at least one odd number */ buf->x[0] |= 1; + buf->x[-1] = (n<<16)|(i<<8)|j; + return 0; } int initstate_r(unsigned seed, char *restrict state, size_t size, struct random_data *restrict buf) { + int n; + if (size < 8) { errno = EINVAL; return -1; } - buf->x = (int32_t*)state + 1; - savestate_r(buf); if (size < 32) { - buf->n = 0; + n = 0; } else if (size < 64) { - buf->n = 7; + n = 7; } else if (size < 128) { - buf->n = 15; + n = 15; } else if (size < 256) { - buf->n = 31; + n = 31; } else { - buf->n = 63; + n = 63; } + buf->x = (int32_t*)state + 1; + buf->x[-1] = (n<<16)|(3<<8); /* (n<<16)|(i<<8)|j */ srandom_r(seed, buf); - savestate_r(buf); return 0; } @@ -127,30 +124,35 @@ int setstate_r(char *restrict state, struct random_data *restrict buf) { return -1; } - savestate_r(buf); - loadstate_r((uint32_t*)state, buf); + buf->x = (int32_t*)state + 1; return 0; } int random_r(struct random_data *restrict buf, int32_t *restrict result) { long k; + int n, i, j; if (result == NULL || buf == NULL) { errno = EINVAL; return -1; } - if (buf->n == 0) { + n = buf->x[-1]>>16; + i = (buf->x[-1]>>8)&0xff; + j = buf->x[-1]&0xff; + + if (n == 0) { k = buf->x[0] = lcg31(buf->x[0]); goto end; } - buf->x[buf->i] += buf->x[buf->j]; - k = buf->x[buf->i]>>1; - if (++(buf->i) == buf->n) { - buf->i = 0; - } if (++(buf->j) == buf->n) { - buf->j = 0; + buf->x[i] += buf->x[j]; + k = buf->x[i]>>1; + if (++i == n) { + i = 0; + } if (++j == n) { + j = 0; } + buf->x[-1] = (n<<16)|(i<<8)|j; end: *result = k; return 0; |