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// SPDX-License-Identifier: BSD-2-Clause
/*
* Copyright (c) 2014, STMicroelectronics International N.V.
*/
#include "mpa.h"
/*************************************************************
*
* LIB FUNCTIONS
*
*************************************************************/
/*------------------------------------------------------------
*
* mpa_mod
*
*/
void mpa_mod(mpanum dest, const mpanum op, const mpanum n, mpa_scratch_mem pool)
{
mpa_div(NULL, dest, op, n, pool);
}
/*------------------------------------------------------------
*
* mpa_add_mod
*
*/
void mpa_add_mod(mpanum dest,
const mpanum op1,
const mpanum op2, const mpanum n, mpa_scratch_mem pool)
{
mpanum tmp_dest;
mpa_alloc_static_temp_var(&tmp_dest, pool);
mpa_add(tmp_dest, op1, op2, pool);
mpa_div(NULL, dest, tmp_dest, n, pool);
mpa_free_static_temp_var(&tmp_dest, pool);
}
/*------------------------------------------------------------
*
* mpa_sub_mod
*
*/
void mpa_sub_mod(mpanum dest,
const mpanum op1,
const mpanum op2, const mpanum n, mpa_scratch_mem pool)
{
mpanum tmp_dest;
mpa_alloc_static_temp_var(&tmp_dest, pool);
mpa_sub(tmp_dest, op1, op2, pool);
mpa_div(NULL, dest, tmp_dest, n, pool);
mpa_free_static_temp_var(&tmp_dest, pool);
}
/*------------------------------------------------------------
*
* mpa_mul_mod
*
*/
void mpa_mul_mod(mpanum dest,
const mpanum op1,
const mpanum op2, const mpanum n, mpa_scratch_mem pool)
{
mpanum tmp_dest;
mpa_alloc_static_temp_var(&tmp_dest, pool);
mpa_mul(tmp_dest, op1, op2, pool);
mpa_div(NULL, dest, tmp_dest, n, pool);
mpa_free_static_temp_var(&tmp_dest, pool);
}
/*------------------------------------------------------------
*
* mpa_inv_mod
*
*/
int mpa_inv_mod(mpanum dest,
const mpanum op, const mpanum n, mpa_scratch_mem pool)
{
mpanum gcd;
mpanum tmp_dest;
int mem_marker;
int res;
if (mpa_cmp_short(op, 1) == 0) {
mpa_set_S32(dest, 1);
return 0;
}
mem_marker = (dest == op);
if (mem_marker)
mpa_alloc_static_temp_var(&tmp_dest, pool);
else
tmp_dest = dest;
mpa_alloc_static_temp_var(&gcd, pool);
/* The function mpa_extended_gcd behaves badly if tmp_dest = op */
mpa_extended_gcd(gcd, tmp_dest, NULL, op, n, pool);
res = mpa_cmp_short(gcd, 1);
if (mem_marker) {
mpa_copy(dest, tmp_dest);
mpa_free_static_temp_var(&tmp_dest, pool);
}
mpa_free_static_temp_var(&gcd, pool);
if (res == 0) {
while (mpa_cmp_short(dest, 0) < 0)
mpa_add(dest, dest, n, pool);
return 0;
} else {
return -1;
}
}
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