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Preserving negative sign in arithmetic-shift. Fixes issue #208.

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This commit is contained in:
Alex Shinn 2014-01-25 21:53:19 +09:00
parent 4b805751f6
commit 48fe3c8014
1 changed files with 3 additions and 2 deletions
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5
lib/srfi/33/bit.c
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@ -135,8 +135,7 @@ static sexp sexp_bit_xor (sexp ctx, sexp self, sexp_sint_t n, sexp x, sexp y) {
/* should probably split into left and right shifts, that's a better */ /* should probably split into left and right shifts, that's a better */
/* interface anyway */ /* interface anyway */
static sexp sexp_arithmetic_shift (sexp ctx, sexp self, sexp_sint_t n, sexp i, sexp count) { static sexp sexp_arithmetic_shift (sexp ctx, sexp self, sexp_sint_t n, sexp i, sexp count) {
sexp_uint_t tmp; sexp_sint_t c, tmp;
sexp_sint_t c;
#if SEXP_USE_BIGNUMS #if SEXP_USE_BIGNUMS
sexp_sint_t len, offset, bit_shift, j; sexp_sint_t len, offset, bit_shift, j;
sexp_gc_var1(res); sexp_gc_var1(res);
@ -177,6 +176,7 @@ static sexp sexp_arithmetic_shift (sexp ctx, sexp self, sexp_sint_t n, sexp i, s
res = sexp_make_fixnum(sexp_bignum_sign(i) > 0 ? 0 : -1); res = sexp_make_fixnum(sexp_bignum_sign(i) > 0 ? 0 : -1);
} else { } else {
res = sexp_make_bignum(ctx, len - offset + 1); res = sexp_make_bignum(ctx, len - offset + 1);
sexp_bignum_sign(res) = sexp_bignum_sign(i);
for (j=len-offset, tmp=0; j>=0; j--) { for (j=len-offset, tmp=0; j>=0; j--) {
sexp_bignum_data(res)[j] sexp_bignum_data(res)[j]
= (sexp_bignum_data(i)[j+offset] >> bit_shift)+ tmp; = (sexp_bignum_data(i)[j+offset] >> bit_shift)+ tmp;
@ -188,6 +188,7 @@ static sexp sexp_arithmetic_shift (sexp ctx, sexp self, sexp_sint_t n, sexp i, s
offset = c / (sizeof(sexp_uint_t)*CHAR_BIT); offset = c / (sizeof(sexp_uint_t)*CHAR_BIT);
bit_shift = c - offset*(sizeof(sexp_uint_t)*CHAR_BIT); bit_shift = c - offset*(sizeof(sexp_uint_t)*CHAR_BIT);
res = sexp_make_bignum(ctx, len + offset + 1); res = sexp_make_bignum(ctx, len + offset + 1);
sexp_bignum_sign(res) = sexp_bignum_sign(i);
for (j=tmp=0; j<len; j++) { for (j=tmp=0; j<len; j++) {
sexp_bignum_data(res)[j+offset] sexp_bignum_data(res)[j+offset]
= (sexp_bignum_data(i)[j] << bit_shift) + tmp; = (sexp_bignum_data(i)[j] << bit_shift) + tmp;