diff options
Diffstat (limited to 'absl/numeric/int128.h')
| -rw-r--r-- | absl/numeric/int128.h | 15 |
1 files changed, 2 insertions, 13 deletions
diff --git a/absl/numeric/int128.h b/absl/numeric/int128.h index 94d2f7ce2985..5e1b3f03c0f2 100644 --- a/absl/numeric/int128.h +++ b/absl/numeric/int128.h @@ -570,25 +570,14 @@ inline uint128& uint128::operator*=(uint128 other) { static_cast<unsigned __int128>(other); return *this; #else // ABSL_HAVE_INTRINSIC128 - uint64_t a96 = hi_ >> 32; - uint64_t a64 = hi_ & 0xffffffff; uint64_t a32 = lo_ >> 32; uint64_t a00 = lo_ & 0xffffffff; - uint64_t b96 = other.hi_ >> 32; - uint64_t b64 = other.hi_ & 0xffffffff; uint64_t b32 = other.lo_ >> 32; uint64_t b00 = other.lo_ & 0xffffffff; - // multiply [a96 .. a00] x [b96 .. b00] - // terms higher than c96 disappear off the high side - // terms c96 and c64 are safe to ignore carry bit - uint64_t c96 = a96 * b00 + a64 * b32 + a32 * b64 + a00 * b96; - uint64_t c64 = a64 * b00 + a32 * b32 + a00 * b64; - this->hi_ = (c96 << 32) + c64; - this->lo_ = 0; - // add terms after this one at a time to capture carry + hi_ = hi_ * other.lo_ + lo_ * other.hi_ + a32 * b32; + lo_ = a00 * b00; *this += uint128(a32 * b00) << 32; *this += uint128(a00 * b32) << 32; - *this += a00 * b00; return *this; #endif // ABSL_HAVE_INTRINSIC128 } |