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/*
* MPI Multiply-Add Core
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_MP_MADD_H__
#define BOTAN_MP_MADD_H__
#include <botan/mp_types.h>
namespace Botan {
#if (BOTAN_MP_WORD_BITS != 64)
#error The mp_asm64 module requires that BOTAN_MP_WORD_BITS == 64
#endif
#if defined(BOTAN_TARGET_ARCH_IS_ALPHA)
#define BOTAN_WORD_MUL(a,b,z1,z0) do { \
asm("umulh %1,%2,%0" : "=r" (z0) : "r" (a), "r" (b)); \
z1 = a * b; \
} while(0);
#elif defined(BOTAN_TARGET_ARCH_IS_IA64)
#define BOTAN_WORD_MUL(a,b,z1,z0) do { \
asm("xmpy.hu %0=%1,%2" : "=f" (z0) : "f" (a), "f" (b)); \
z1 = a * b; \
} while(0);
#elif defined(BOTAN_TARGET_ARCH_IS_PPC64)
#define BOTAN_WORD_MUL(a,b,z1,z0) do { \
asm("mulhdu %0,%1,%2" : "=r" (z0) : "r" (a), "r" (b) : "cc"); \
z1 = a * b; \
} while(0);
#elif defined(BOTAN_TARGET_ARCH_IS_MIPS64)
#define BOTAN_WORD_MUL(a,b,z1,z0) do { \
typedef unsigned int uint128_t __attribute__((mode(TI))); \
uint128_t r = (uint128_t)a * b; \
z0 = (r >> 64) & 0xFFFFFFFFFFFFFFFF; \
z1 = (r ) & 0xFFFFFFFFFFFFFFFF; \
} while(0);
#else
// Do a 64x64->128 multiply using four 64x64->64 multiplies
// plus some adds and shifts. Last resort for CPUs like UltraSPARC,
// with 64-bit registers/ALU, but no 64x64->128 multiply.
inline void bigint_2word_mul(word a, word b, word* z1, word* z0)
{
const size_t MP_HWORD_BITS = BOTAN_MP_WORD_BITS / 2;
const word MP_HWORD_MASK = ((word)1 << MP_HWORD_BITS) - 1;
const word a_hi = (a >> MP_HWORD_BITS);
const word a_lo = (a & MP_HWORD_MASK);
const word b_hi = (b >> MP_HWORD_BITS);
const word b_lo = (b & MP_HWORD_MASK);
word x0 = a_hi * b_hi;
word x1 = a_lo * b_hi;
word x2 = a_hi * b_lo;
word x3 = a_lo * b_lo;
x2 += x3 >> (MP_HWORD_BITS);
x2 += x1;
if(x2 < x1) // timing channel
x0 += ((word)1 << MP_HWORD_BITS);
*z0 = x0 + (x2 >> MP_HWORD_BITS);
*z1 = ((x2 & MP_HWORD_MASK) << MP_HWORD_BITS) + (x3 & MP_HWORD_MASK);
}
#define BOTAN_WORD_MUL(a,b,z1,z0) bigint_2word_mul(a, b, &z1, &z0)
#endif
/*
* Word Multiply/Add
*/
inline word word_madd2(word a, word b, word* c)
{
word z0 = 0, z1 = 0;
BOTAN_WORD_MUL(a, b, z1, z0);
z1 += *c;
z0 += (z1 < *c);
*c = z0;
return z1;
}
/*
* Word Multiply/Add
*/
inline word word_madd3(word a, word b, word c, word* d)
{
word z0 = 0, z1 = 0;
BOTAN_WORD_MUL(a, b, z1, z0);
z1 += c;
z0 += (z1 < c);
z1 += *d;
z0 += (z1 < *d);
*d = z0;
return z1;
}
}
#endif
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