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/*************************************************
* Lowest Level MPI Algorithms Source File *
* (C) 1999-2006 The Botan Project *
*************************************************/
#include <botan/mp_asm.h>
#include <botan/mp_asmi.h>
#include <botan/mp_core.h>
#include <botan/mem_ops.h>
namespace Botan {
extern "C" {
/*************************************************
* Two Operand Addition, No Carry *
*************************************************/
word bigint_add2_nc(word x[], u32bit x_size, const word y[], u32bit y_size)
{
word carry = 0;
const u32bit blocks = y_size - (y_size % 8);
for(u32bit j = 0; j != blocks; j += 8)
carry = word8_add2(x + j, y + j, carry);
for(u32bit j = blocks; j != y_size; ++j)
x[j] = word_add(x[j], y[j], &carry);
if(!carry)
return 0;
for(u32bit j = y_size; j != x_size; ++j)
if(++x[j])
return 0;
return 1;
}
/*************************************************
* Three Operand Addition, No Carry *
*************************************************/
word bigint_add3_nc(word z[], const word x[], u32bit x_size,
const word y[], u32bit y_size)
{
if(x_size < y_size)
{ return bigint_add3_nc(z, y, y_size, x, x_size); }
word carry = 0;
const u32bit blocks = y_size - (y_size % 8);
for(u32bit j = 0; j != blocks; j += 8)
carry = word8_add3(z + j, x + j, y + j, carry);
for(u32bit j = blocks; j != y_size; ++j)
z[j] = word_add(x[j], y[j], &carry);
for(u32bit j = y_size; j != x_size; ++j)
{
word x_j = x[j] + carry;
if(carry && x_j)
carry = 0;
z[j] = x_j;
}
return carry;
}
/*************************************************
* Two Operand Addition *
*************************************************/
void bigint_add2(word x[], u32bit x_size, const word y[], u32bit y_size)
{
if(bigint_add2_nc(x, x_size, y, y_size))
++x[x_size];
}
/*************************************************
* Three Operand Addition *
*************************************************/
void bigint_add3(word z[], const word x[], u32bit x_size,
const word y[], u32bit y_size)
{
if(bigint_add3_nc(z, x, x_size, y, y_size))
++z[(x_size > y_size ? x_size : y_size)];
}
/*************************************************
* Two Operand Subtraction *
*************************************************/
void bigint_sub2(word x[], u32bit x_size, const word y[], u32bit y_size)
{
word carry = 0;
const u32bit blocks = y_size - (y_size % 8);
for(u32bit j = 0; j != blocks; j += 8)
carry = word8_sub2(x + j, y + j, carry);
for(u32bit j = blocks; j != y_size; ++j)
x[j] = word_sub(x[j], y[j], &carry);
if(!carry) return;
for(u32bit j = y_size; j != x_size; ++j)
{
--x[j];
if(x[j] != MP_WORD_MAX) return;
}
}
/*************************************************
* Three Operand Subtraction *
*************************************************/
void bigint_sub3(word z[], const word x[], u32bit x_size,
const word y[], u32bit y_size)
{
word carry = 0;
const u32bit blocks = y_size - (y_size % 8);
for(u32bit j = 0; j != blocks; j += 8)
carry = word8_sub3(z + j, x + j, y + j, carry);
for(u32bit j = blocks; j != y_size; ++j)
z[j] = word_sub(x[j], y[j], &carry);
for(u32bit j = y_size; j != x_size; ++j)
{
word x_j = x[j] - carry;
if(carry && x_j != MP_WORD_MAX)
carry = 0;
z[j] = x_j;
}
}
/*************************************************
* Two Operand Linear Multiply *
*************************************************/
void bigint_linmul2(word x[], u32bit x_size, word y)
{
const u32bit blocks = x_size - (x_size % 8);
word carry = 0;
for(u32bit j = 0; j != blocks; j += 8)
carry = word8_linmul2(x + j, y, carry);
for(u32bit j = blocks; j != x_size; ++j)
x[j] = word_madd2(x[j], y, &carry);
x[x_size] = carry;
}
/*************************************************
* Three Operand Linear Multiply *
*************************************************/
void bigint_linmul3(word z[], const word x[], u32bit x_size, word y)
{
const u32bit blocks = x_size - (x_size % 8);
word carry = 0;
for(u32bit j = 0; j != blocks; j += 8)
carry = word8_linmul3(z + j, x + j, y, carry);
for(u32bit j = blocks; j != x_size; ++j)
z[j] = word_madd2(x[j], y, &carry);
z[x_size] = carry;
}
/*************************************************
* Simple O(N^2) Multiplication *
*************************************************/
void bigint_simple_mul(word z[], const word x[], u32bit x_size,
const word y[], u32bit y_size)
{
const u32bit blocks = y_size - (y_size % 8);
clear_mem(z, x_size + y_size);
for(u32bit j = 0; j != x_size; ++j)
{
const word x_j = x[j];
word carry = 0;
for(u32bit k = 0; k != blocks; k += 8)
carry = word8_madd3(z + j + k, y + k, x_j, carry);
for(u32bit k = blocks; k != y_size; ++k)
z[j+k] = word_madd3(x_j, y[k], z[j+k], &carry);
z[j+y_size] = carry;
}
}
/*************************************************
* Montgomery Reduction Algorithm *
*************************************************/
void montgomery_reduce(word z[], u32bit z_size,
const word x[], u32bit x_size, word u)
{
for(u32bit j = 0; j != x_size; ++j)
{
word* z_j = z + j;
const word y = z_j[0] * u;
word carry = 0;
const u32bit blocks = x_size - (x_size % 8);
for(u32bit k = 0; k != blocks; k += 8)
carry = word8_madd3(z_j + k, x + k, y, carry);
for(u32bit k = blocks; k != x_size; ++k)
z_j[k] = word_madd3(x[k], y, z_j[k], &carry);
word carry2 = 0;
z_j[x_size] = word_add(z_j[x_size], carry, &carry2);
carry = carry2;
for(u32bit k = x_size + 1; carry && k != z_size - j; ++k)
{
++z_j[k];
carry = !z_j[k];
}
}
if(bigint_cmp(z + x_size, x_size + 1, x, x_size) >= 0)
bigint_sub2(z + x_size, x_size + 1, x, x_size);
}
}
}
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