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Fast-path bignum remainder on fixnum powers of two.

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Alex Shinn 2014-01-05 07:08:40 -05:00
parent 2c46b2d8ab
commit f32daf3b96
1 changed files with 5 additions and 0 deletions
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5
bignum.c
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@ -223,6 +223,11 @@ sexp sexp_bignum_fxrem (sexp ctx, sexp a, sexp_sint_t b) {
sexp_uint_t len=sexp_bignum_hi(a), *data=sexp_bignum_data(a), q, b0; sexp_uint_t len=sexp_bignum_hi(a), *data=sexp_bignum_data(a), q, b0;
int i; int i;
sexp_luint_t n = 0; sexp_luint_t n = 0;
if (b > 0) {
q = b - 1;
if ((b & q) == 0)
return sexp_make_fixnum(sexp_bignum_sign(a) * (data[0] & q));
}
b0 = (b >= 0) ? b : -b; b0 = (b >= 0) ? b : -b;
for (i=len-1; i>=0; i--) { for (i=len-1; i>=0; i--) {
n = (n << sizeof(sexp_uint_t)*8) + data[i]; n = (n << sizeof(sexp_uint_t)*8) + data[i];