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/*
* Lowest Level MPI Algorithms
* (C) 1999-2008,2013 Jack Lloyd
* 2006 Luca Piccarreta
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_MP_WORD_MULADD_H_
#define BOTAN_MP_WORD_MULADD_H_
#include <botan/types.h>
#include <botan/mul128.h>
namespace Botan {
#if (BOTAN_MP_WORD_BITS == 32)
typedef uint64_t dword;
#define BOTAN_HAS_MP_DWORD
#elif (BOTAN_MP_WORD_BITS == 64)
#if defined(BOTAN_TARGET_HAS_NATIVE_UINT128)
typedef uint128_t dword;
#define BOTAN_HAS_MP_DWORD
#else
// No native 128 bit integer type; use mul64x64_128 instead
#endif
#else
#error BOTAN_MP_WORD_BITS must be 32 or 64
#endif
#if defined(BOTAN_USE_GCC_INLINE_ASM)
#if defined(BOTAN_TARGET_ARCH_IS_X86_32) && (BOTAN_MP_WORD_BITS == 32)
#define BOTAN_MP_USE_X86_32_ASM
#elif defined(BOTAN_TARGET_ARCH_IS_X86_64) && (BOTAN_MP_WORD_BITS == 64)
#define BOTAN_MP_USE_X86_64_ASM
#endif
#endif
/*
* Word Multiply/Add
*/
inline word word_madd2(word a, word b, word* c)
{
#if defined(BOTAN_MP_USE_X86_32_ASM)
asm(R"(
mull %[b]
addl %[c],%[a]
adcl $0,%[carry]
)"
: [a]"=a"(a), [b]"=rm"(b), [carry]"=&d"(*c)
: "0"(a), "1"(b), [c]"g"(*c) : "cc");
return a;
#elif defined(BOTAN_MP_USE_X86_64_ASM)
asm(R"(
mulq %[b]
addq %[c],%[a]
adcq $0,%[carry]
)"
: [a]"=a"(a), [b]"=rm"(b), [carry]"=&d"(*c)
: "0"(a), "1"(b), [c]"g"(*c) : "cc");
return a;
#elif defined(BOTAN_HAS_MP_DWORD)
const dword s = static_cast<dword>(a) * b + *c;
*c = static_cast<word>(s >> BOTAN_MP_WORD_BITS);
return static_cast<word>(s);
#else
static_assert(BOTAN_MP_WORD_BITS == 64, "Unexpected word size");
word hi = 0, lo = 0;
mul64x64_128(a, b, &lo, &hi);
lo += *c;
hi += (lo < *c); // carry?
*c = hi;
return lo;
#endif
}
/*
* Word Multiply/Add
*/
inline word word_madd3(word a, word b, word c, word* d)
{
#if defined(BOTAN_MP_USE_X86_32_ASM)
asm(R"(
mull %[b]
addl %[c],%[a]
adcl $0,%[carry]
addl %[d],%[a]
adcl $0,%[carry]
)"
: [a]"=a"(a), [b]"=rm"(b), [carry]"=&d"(*d)
: "0"(a), "1"(b), [c]"g"(c), [d]"g"(*d) : "cc");
return a;
#elif defined(BOTAN_MP_USE_X86_64_ASM)
asm(R"(
mulq %[b]
addq %[c],%[a]
adcq $0,%[carry]
addq %[d],%[a]
adcq $0,%[carry]
)"
: [a]"=a"(a), [b]"=rm"(b), [carry]"=&d"(*d)
: "0"(a), "1"(b), [c]"g"(c), [d]"g"(*d) : "cc");
return a;
#elif defined(BOTAN_HAS_MP_DWORD)
const dword s = static_cast<dword>(a) * b + c + *d;
*d = static_cast<word>(s >> BOTAN_MP_WORD_BITS);
return static_cast<word>(s);
#else
static_assert(BOTAN_MP_WORD_BITS == 64, "Unexpected word size");
word hi = 0, lo = 0;
mul64x64_128(a, b, &lo, &hi);
lo += c;
hi += (lo < c); // carry?
lo += *d;
hi += (lo < *d); // carry?
*d = hi;
return lo;
#endif
}
}
#endif
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