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fix bn.c

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NIIBE Yutaka
2014-03-19 23:47:19 +09:00
parent 116486affa
commit fa10e78344
2 changed files with 10 additions and 3 deletions
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3
ChangeLog
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@@ -1,5 +1,8 @@
2014-03-19 Niibe Yutaka <gniibe@fsij.org> 2014-03-19 Niibe Yutaka <gniibe@fsij.org>
* src/bn.c (bn256_add): Fix for X == B.
(bn256_sub): Likewise.
* src/ecc-edwards.c: New. * src/ecc-edwards.c: New.
2014-03-18 Niibe Yutaka <gniibe@fsij.org> 2014-03-18 Niibe Yutaka <gniibe@fsij.org>

10
src/bn.c
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@@ -30,6 +30,7 @@ uint32_t
bn256_add (bn256 *X, const bn256 *A, const bn256 *B) bn256_add (bn256 *X, const bn256 *A, const bn256 *B)
{ {
int i; int i;
uint32_t v;
uint32_t carry = 0; uint32_t carry = 0;
uint32_t *px; uint32_t *px;
const uint32_t *pa, *pb; const uint32_t *pa, *pb;
@@ -40,9 +41,10 @@ bn256_add (bn256 *X, const bn256 *A, const bn256 *B)
for (i = 0; i < BN256_WORDS; i++) for (i = 0; i < BN256_WORDS; i++)
{ {
v = *pb;
*px = *pa + carry; *px = *pa + carry;
carry = (*px < carry); carry = (*px < carry);
*px += *pb; *px += v;
carry += (*px < *pb); carry += (*px < *pb);
px++; px++;
pa++; pa++;
@@ -56,6 +58,7 @@ uint32_t
bn256_sub (bn256 *X, const bn256 *A, const bn256 *B) bn256_sub (bn256 *X, const bn256 *A, const bn256 *B)
{ {
int i; int i;
uint32_t v;
uint32_t borrow = 0; uint32_t borrow = 0;
uint32_t *px; uint32_t *px;
const uint32_t *pa, *pb; const uint32_t *pa, *pb;
@@ -68,9 +71,10 @@ bn256_sub (bn256 *X, const bn256 *A, const bn256 *B)
{ {
uint32_t borrow0 = (*pa < borrow); uint32_t borrow0 = (*pa < borrow);
v = *pb;
*px = *pa - borrow; *px = *pa - borrow;
borrow = (*px < *pb) + borrow0; borrow = (*px < v) + borrow0;
*px -= *pb; *px -= v;
px++; px++;
pa++; pa++;
pb++; pb++;