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scalar: adjust muladd2 to new int128 interface

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This commit is contained in:
Jonas Nick 2023-07-27 10:14:06 +00:00
parent b160486766
commit 579999b425
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GPG Key ID: 4861DBF262123605
1 changed files with 4 additions and 3 deletions
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src/scalar_4x64_impl.h
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@ -254,9 +254,10 @@ static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) {
#define muladd2(a,b) { \
uint64_t tl, th, th2, tl2; \
{ \
uint128_t t = (uint128_t)a * b; \
th = t >> 64; /* at most 0xFFFFFFFFFFFFFFFE */ \
tl = t; \
secp256k1_uint128 t; \
secp256k1_u128_mul(&t, a, b); \
th = secp256k1_u128_hi_u64(&t); /* at most 0xFFFFFFFFFFFFFFFE */ \
tl = secp256k1_u128_to_u64(&t); \
} \
th2 = th + th; /* at most 0xFFFFFFFFFFFFFFFE (in case th was 0x7FFFFFFFFFFFFFFF) */ \
c2 += (th2 < th); /* never overflows by contract (verified the next line) */ \