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/*
* Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <string.h>
#include <ipxe/bigint.h>
/** @file
*
* Big integer support
*/
/**
* Multiply big integers
*
* @v multiplicand0 Element 0 of big integer to be multiplied
* @v multiplier0 Element 0 of big integer to be multiplied
* @v result0 Element 0 of big integer to hold result
* @v size Number of elements
*/
void bigint_multiply_raw ( const uint32_t *multiplicand0,
const uint32_t *multiplier0,
uint32_t *result0, unsigned int size ) {
const bigint_t ( size ) __attribute__ (( may_alias )) *multiplicand =
( ( const void * ) multiplicand0 );
const bigint_t ( size ) __attribute__ (( may_alias )) *multiplier =
( ( const void * ) multiplier0 );
bigint_t ( size * 2 ) __attribute__ (( may_alias )) *result =
( ( void * ) result0 );
unsigned int i;
unsigned int j;
uint32_t multiplicand_element;
uint32_t multiplier_element;
uint32_t *result_elements;
uint32_t discard_a;
uint32_t discard_d;
long index;
/* Zero result */
memset ( result, 0, sizeof ( *result ) );
/* Multiply integers one element at a time */
for ( i = 0 ; i < size ; i++ ) {
multiplicand_element = multiplicand->element[i];
for ( j = 0 ; j < size ; j++ ) {
multiplier_element = multiplier->element[j];
result_elements = &result->element[ i + j ];
/* Perform a single multiply, and add the
* resulting double-element into the result,
* carrying as necessary. The carry can
* never overflow beyond the end of the
* result, since:
*
* a < 2^{n}, b < 2^{n} => ab < 2^{2n}
*/
__asm__ __volatile__ ( "mull %4\n\t"
"addl %%eax, (%5,%2,4)\n\t"
"adcl %%edx, 4(%5,%2,4)\n\t"
"\n1:\n\t"
"adcl $0, 8(%5,%2,4)\n\t"
"inc %2\n\t"
/* Does not affect CF */
"jc 1b\n\t"
: "=&a" ( discard_a ),
"=&d" ( discard_d ),
"=&r" ( index )
: "0" ( multiplicand_element ),
"g" ( multiplier_element ),
"r" ( result_elements ),
"2" ( 0 ) );
}
}
}
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