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// SPDX-License-Identifier: BSD-2-Clause
/*
* Copyright (c) 2014, STMicroelectronics International N.V.
*/
#include "mpa.h"
/*************************************************************
*
* HELPERS
*
*************************************************************/
/*------------------------------------------------------------
*
* These functions have ARM assembler implementations
*
*/
#if !defined(USE_ARM_ASM)
/* --------------------------------------------------------------------
* Function: __mpa_mul_add_word
*
* Multiplies a and b and adds the incoming carry to produce the product p
* outgoing carry is stored in *carry.
*/
void __mpa_mul_add_word(mpa_word_t a,
mpa_word_t b, mpa_word_t *p, mpa_word_t *carry)
{
#if defined(MPA_SUPPORT_DWORD_T)
mpa_dword_t prod;
prod = (mpa_dword_t) (a) * (mpa_dword_t) (b) + (mpa_dword_t) (*carry);
*p = (mpa_word_t) prod;
*carry = (mpa_word_t) (prod >> MPA_WORD_SIZE);
#else
#error "error, write non-dword_t code for __mpa_mul_add_word"
#endif
}
/* --------------------------------------------------------------------
* Function: __mpa_mul_add_word_cum
*
* Multiplies a and b and adds the incoming carry and the cumulative
* product stored in *p.
* Outgoing carry is stored in *carry.
*/
void __mpa_mul_add_word_cum(mpa_word_t a,
mpa_word_t b, mpa_word_t *p, mpa_word_t *carry)
{
#if defined(MPA_SUPPORT_DWORD_T)
mpa_dword_t prod;
prod =
(mpa_dword_t) (a) * (mpa_dword_t) (b) + (mpa_dword_t) (*p) +
(mpa_dword_t) (*carry);
*p = (mpa_word_t) prod;
*carry = (mpa_word_t) (prod >> MPA_WORD_SIZE);
#else
#error "error: write non-dword_t code for __mpa_mul_add_word_cum"
#endif
}
#endif /* USE_ARM_ASM */
/* --------------------------------------------------------------------
* Function: __mpa_abs_mul_word
*
* Simpler multiplication when one operand is known to be a word.
* Calculates |op1| * op2, op2 is always positive (larger than zero).
* Dest needs to be distinct from op1.
*/
void __mpa_abs_mul_word(mpanum dest, const mpanum op1, mpa_word_t op2)
{
mpa_word_t i;
mpa_word_t carry;
mpa_word_t *prod;
const mpa_word_t *a;
/* clear dest digits */
mpa_memset(dest->d, 0, dest->alloc * BYTES_PER_WORD);
a = op1->d;
prod = dest->d;
carry = 0;
for (i = 0; i < __mpanum_size(op1); i++) {
__mpa_mul_add_word(*a, op2, prod + i, &carry);
a++;
}
dest->size = i;
if (carry) {
*(prod + i) = carry;
dest->size++;
}
}
/* --------------------------------------------------------------------
* Function: __mpa_abs_mul
*
* Calculates |op1| * |op2| and puts result in dest.
* dest must be big enough to hold result and cannot be
* the same as op1 or op2.
*/
void __mpa_abs_mul(mpanum dest, const mpanum op1, const mpanum op2)
{
mpa_word_t i = 0;
mpa_word_t j = 0;
mpa_word_t carry = 0;
mpa_word_t *prod;
const mpa_word_t *a;
const mpa_word_t *b;
/* clear dest digits */
mpa_memset(dest->d, 0, dest->alloc * BYTES_PER_WORD);
a = op1->d;
prod = dest->d;
for (i = 0; i < __mpanum_size(op1); i++) {
b = op2->d;
carry = 0;
for (j = 0; j < __mpanum_size(op2); j++) {
__mpa_mul_add_word_cum(*a, *b, prod + j, &carry);
b++;
}
if (carry)
*(prod + j) = carry;
a++;
prod++;
}
dest->size = i + j - 1;
if (carry)
dest->size++;
}
/*************************************************************
*
* LIB FUNCTIONS
*
*************************************************************/
/* --------------------------------------------------------------------
* Function: mpa_mul
*
* dest = op1 * op2
*/
void mpa_mul(mpanum dest,
const mpanum op1, const mpanum op2, mpa_scratch_mem pool)
{
mpanum tmp_dest;
char mem_marker;
if (__mpanum_is_zero(op1) || __mpanum_is_zero(op2)) {
mpa_set_word(dest, 0);
return;
}
/* handle the case when dest is one of the operands */
mem_marker = (dest == op1 || dest == op2);
if (mem_marker)
mpa_alloc_static_temp_var(&tmp_dest, pool);
else
tmp_dest = dest;
__mpa_abs_mul(tmp_dest, op1, op2);
if (__mpanum_sign(op1) != __mpanum_sign(op2))
__mpanum_neg(tmp_dest);
mpa_copy(dest, tmp_dest);
if (mem_marker)
mpa_free_static_temp_var(&tmp_dest, pool);
}
/* --------------------------------------------------------------------
* Function: mpa_mul_word
*
* Calculates op1 * op2, where op2 is a word, puts result in dest.
*/
void mpa_mul_word(mpanum dest,
const mpanum op1, mpa_word_t op2, mpa_scratch_mem pool)
{
int sign_1;
mpanum tmp_dest;
char mem_marker;
if (__mpanum_is_zero(op1) || op2 == 0) {
mpa_set_word(dest, 0);
return;
}
sign_1 = __mpanum_sign(op1);
/* handle the case when dest is the operand */
mem_marker = (dest == op1);
if (mem_marker)
mpa_alloc_static_temp_var(&tmp_dest, pool);
else
tmp_dest = dest;
__mpa_abs_mul_word(tmp_dest, op1, op2);
if (sign_1 == MPA_NEG_SIGN)
__mpanum_neg(tmp_dest);
mpa_copy(dest, tmp_dest);
if (mem_marker)
mpa_free_static_temp_var(&tmp_dest, pool);
}
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