2 * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20 FILE_LICENCE ( GPL2_OR_LATER );
24 #include <ipxe/bigint.h>
32 * Multiply big integers
34 * @v multiplicand0 Element 0 of big integer to be multiplied
35 * @v multiplier0 Element 0 of big integer to be multiplied
36 * @v result0 Element 0 of big integer to hold result
37 * @v size Number of elements
39 void bigint_multiply_raw ( const uint32_t *multiplicand0,
40 const uint32_t *multiplier0,
41 uint32_t *result0, unsigned int size ) {
42 const bigint_t ( size ) __attribute__ (( may_alias )) *multiplicand =
43 ( ( const void * ) multiplicand0 );
44 const bigint_t ( size ) __attribute__ (( may_alias )) *multiplier =
45 ( ( const void * ) multiplier0 );
46 bigint_t ( size * 2 ) __attribute__ (( may_alias )) *result =
47 ( ( void * ) result0 );
50 uint32_t multiplicand_element;
51 uint32_t multiplier_element;
52 uint32_t *result_elements;
58 memset ( result, 0, sizeof ( *result ) );
60 /* Multiply integers one element at a time */
61 for ( i = 0 ; i < size ; i++ ) {
62 multiplicand_element = multiplicand->element[i];
63 for ( j = 0 ; j < size ; j++ ) {
64 multiplier_element = multiplier->element[j];
65 result_elements = &result->element[ i + j ];
66 /* Perform a single multiply, and add the
67 * resulting double-element into the result,
68 * carrying as necessary. The carry can
69 * never overflow beyond the end of the
72 * a < 2^{n}, b < 2^{n} => ab < 2^{2n}
74 __asm__ __volatile__ ( "mull %4\n\t"
75 "addl %%eax, (%5,%2,4)\n\t"
76 "adcl %%edx, 4(%5,%2,4)\n\t"
78 "adcl $0, 8(%5,%2,4)\n\t"
80 /* Does not affect CF */
82 : "=&a" ( discard_a ),
85 : "0" ( multiplicand_element ),
86 "g" ( multiplier_element ),
87 "r" ( result_elements ),