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// SPDX-License-Identifier: BSD-2-Clause
/*
* Copyright (c) 2014, STMicroelectronics International N.V.
*/
#include "mpa.h"
/*************************************************************
*
* GLOBAL CONSTANTS
*
*************************************************************/
const mpa_num_base const_largest_deci_base = {
1, 1, {LARGEST_DECIMAL_BASE_IN_WORD} };
const mpa_num_base Const_1_LShift_Base = { 2, 2, {0, 1} };
const mpa_num_base const_one = { 1, 1, {1} };
/*************************************************************
*
* HELPERS
*
*************************************************************/
/* --------------------------------------------------------------------
* Function: __mpa_set_unused_digits_to_zero
*
*
*/
void __mpa_set_unused_digits_to_zero(mpanum n)
{
int i;
/*
* Pointer arithmetics on *mpa_word_t will put the
* pointer at the right place.
*/
i = __mpanum_size(n);
mpa_memset((n->d) + i, 0, (n->alloc - i) * BYTES_PER_WORD);
}
/*************************************************************
*
* LIB FUNCTIONS
*
*************************************************************/
/*------------------------------------------------------------
*
* mpa_wipe
*
* fills the digits with zero and set size = 0;
*
*/
void mpa_wipe(mpanum var)
{
mpa_memset(var->d, 0, var->alloc * BYTES_PER_WORD);
var->size = 0;
}
/*------------------------------------------------------------
*
* mpa_copy
*
* Copies src to dest.
*
* Doesn't check if src fits into dest
*
*/
void mpa_copy(mpanum dest, const mpanum src)
{
if (dest == src)
return;
mpa_memcpy(dest->d, src->d, __mpanum_size(src) * BYTES_PER_WORD);
dest->size = src->size;
}
/* --------------------------------------------------------------------
* Function: mpa_abs
* Computes the absolut value of src and puts it in dest
* dest and src can be the same mpanum
*/
void mpa_abs(mpanum dest, const mpanum src)
{
mpa_copy(dest, src);
__mpanum_set_sign(dest, MPA_POS_SIGN);
}
/* --------------------------------------------------------------------
* Function: mpa_highest_bit_index
* Returns the index of the highest 1 in |src|.
* The index starts at 0 for the least significant bit.
* If src == zero, it will return -1
*
*/
int mpa_highest_bit_index(const mpanum src)
{
mpa_word_t w;
mpa_word_t b;
if (__mpanum_is_zero(src))
return -1;
w = __mpanum_msw(src);
for (b = 0; b < WORD_SIZE; b++) {
w >>= 1;
if (w == 0)
break;
}
return (int)(__mpanum_size(src) - 1) * WORD_SIZE + b;
}
/*------------------------------------------------------------
*
* mpa_get_bit
*
* Returns the value of the idx:th bit in src.
* if idx is larger than the number of bits in src,
* it returns zero.
*
*/
uint32_t mpa_get_bit(const mpanum src, uint32_t idx)
{
mpa_word_t w; /* word of bitIndex */
unsigned long b; /* bit number in that word */
w = idx >> LOG_OF_WORD_SIZE;
b = idx & (WORD_SIZE - 1);
if (w > __mpanum_size(src))
return 0;
b = (1ul << b);
return ((src->d[w] & b) != 0);
}
/*------------------------------------------------------------
*
* mpa_CanHold
*
* returns 1 if dest can hold src without overflowing, 0 otherwise
*/
int mpa_can_hold(mpanum dest, const mpanum src)
{
return (__mpanum_alloced(dest) >= __mpanum_size(src) ? 1 : 0);
}
/*------------------------------------------------------------
*
* mpa_parity
*
*/
int mpa_parity(const mpanum src)
{
return (((__mpanum_lsw(src) & 0x01) ==
0) ? MPA_EVEN_PARITY : MPA_ODD_PARITY);
}
/*------------------------------------------------------------
*
* mpa_constant_one
*
*/
mpanum mpa_constant_one(void)
{
return (mpanum)&const_one;
}
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