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bignum: incorporate some fixes from @slavapestov.

John Benediktsson 2012-08-10 14:28:44 -07:00
parent 0405b6cebb
commit 5d8ffbc23b
1 changed files with 11 additions and 19 deletions
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30
vm/bignum.cpp
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@ -1721,33 +1721,29 @@ bignum * factor_vm::bignum_gcd(bignum * a, bignum * b)
bignum_digit_type * scan_a, * scan_b, * scan_d, * a_end, * b_end;
if (BIGNUM_NEGATIVE_P (a)) {
scan_a = BIGNUM_START_PTR (a);
size_a = BIGNUM_LENGTH (a);
a_end = scan_a + size_a;
d = allot_bignum (size_a, 0);
GC_BIGNUM(d);
scan_d = BIGNUM_START_PTR (d);
scan_a = BIGNUM_START_PTR (a);
a_end = scan_a + size_a;
while (scan_a < a_end)
(*scan_d++) = (*scan_a++);
a = d;
}
if (BIGNUM_NEGATIVE_P (b)) {
scan_b = BIGNUM_START_PTR (b);
size_b = BIGNUM_LENGTH (b);
b_end = scan_b + size_b;
d = allot_bignum (size_b, 0);
GC_BIGNUM(d);
scan_d = BIGNUM_START_PTR (d);
scan_b = BIGNUM_START_PTR (b);
b_end = scan_b + size_b;
while (scan_b < b_end)
(*scan_d++) = (*scan_b++);
b = d;
}
if (bignum_compare(a, b) == bignum_comparison_less) {
d = a;
a = b;
b = d;
std::swap(a, b);
}
while (BIGNUM_LENGTH (b) != 0) {
@ -1776,19 +1772,19 @@ bignum * factor_vm::bignum_gcd(bignum * a, bignum * b)
bignum_digit_type *a_end, *b_end, *c_end;
/* clone the bignums so we can modify them in-place */
scan_a = BIGNUM_START_PTR (a);
size_a = BIGNUM_LENGTH (a);
a_end = scan_a + size_a;
c = allot_bignum (size_a, 0);
scan_a = BIGNUM_START_PTR (a);
a_end = scan_a + size_a;
GC_BIGNUM(c);
scan_c = BIGNUM_START_PTR (c);
while (scan_a < a_end)
(*scan_c++) = (*scan_a++);
a = c;
scan_b = BIGNUM_START_PTR (b);
size_b = BIGNUM_LENGTH (b);
b_end = scan_b + size_b;
d = allot_bignum (size_b, 0);
scan_b = BIGNUM_START_PTR (b);
b_end = scan_b + size_b;
GC_BIGNUM(d);
scan_d = BIGNUM_START_PTR (d);
while (scan_b < b_end)
@ -1797,12 +1793,8 @@ bignum * factor_vm::bignum_gcd(bignum * a, bignum * b)
/* Initial reduction: make sure that 0 <= b <= a. */
if (bignum_compare(a, b) == bignum_comparison_less) {
c = a;
size_c = size_a;
a = b;
size_a = size_b;
b = c;
size_b = size_c;
std::swap(a, b);
std::swap(size_a, size_b);
}
while (size_a > 1) {