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BigNum128.cpp
48 lines (39 loc) · 1.3 KB
/
BigNum128.cpp
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/*
* Copyright (c) 1998-2013 Apple Computer, Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* The contents of this file constitute Original Code as defined in and
* are subject to the Apple Public Source License Version 1.1 (the
* "License"). You may not use this file except in compliance with the
* License. Please obtain a copy of the License at
* http://www.apple.com/publicsource and read it before using this file.
*
* This Original Code and all software distributed under the License are
* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
* License for the specific language governing rights and limitations
* under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
#include "BigNum128.h"
U128 UInt64mult(const uint64_t A, const uint64_t B)
{
U128 result;
uint64_t a1, a0, b1, b0;
a1 = A >> 32;
a0 = A - (a1 << 32);
b1 = B >> 32;
b0 = B - (b1 << 32);
uint64_t X, Y, Z;
X = a1 * b1;
Y = a0 * b0;
Z = a1 * b0 + a0 * b1;
uint64_t z1, z0;
z1 = Z >> 32;
z0 = Z - (z1 << 32);
return U128(X, 0) + U128(z1, uint64_t(z0) << 32) + U128(0, Y);
}