Fcalva/chibi-scheme
1
0
Fork 0
mirror of https://github.com/ashinn/chibi-scheme.git synced 2025-05-19 05:39:18 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

random_r doesn't necessarily provide enough bits even for a fixnum (issue #668)

Browse source
This commit is contained in:
Alex Shinn 2020-07-13 10:27:04 +09:00
parent 9940e0d053
commit b4fb077fef
1 changed files with 7 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

9
lib/srfi/27/rand.c
View file

@ -55,7 +55,8 @@ typedef unsigned int sexp_random_t;
sexp sexp_rs_random_integer (sexp ctx, sexp self, sexp_sint_t n, sexp rs, sexp bound) {
sexp res;
sexp_int32_t m;
int64_t m;
sexp_int32_t m2;
#if SEXP_USE_BIGNUMS
sexp_uint_t mod;
sexp_uint32_t *data;
@ -67,7 +68,11 @@ sexp sexp_rs_random_integer (sexp ctx, sexp self, sexp_sint_t n, sexp rs, sexp b
if (sexp_unbox_fixnum(bound) <= 0) {
res = sexp_xtype_exception(ctx, self, "random bound must be positive", bound);
} else {
sexp_call_random(rs, m);
/* ensure we have sufficient bits */
for (i=m=0; i <= 1<<(CHAR_BIT*sizeof(m))/RAND_MAX; ++i) {
sexp_call_random(rs, m2);
m = m * RAND_MAX + m2;
}
res = sexp_make_fixnum(m % sexp_unbox_fixnum(bound));
}
#if SEXP_USE_BIGNUMS