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#include "tommath_private.h"
#ifdef BN_MP_EXPORT_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is a library that provides multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library was designed directly after the MPI library by
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* SPDX-License-Identifier: Unlicense
*/
/* based on gmp's mpz_export.
* see http://gmplib.org/manual/Integer-Import-and-Export.html
*/
int mp_export(void *rop, size_t *countp, int order, size_t size,
int endian, size_t nails, const mp_int *op)
{
int result;
size_t odd_nails, nail_bytes, i, j, bits, count;
unsigned char odd_nail_mask;
mp_int t;
if ((result = mp_init_copy(&t, op)) != MP_OKAY) {
return result;
}
if (endian == 0) {
union {
unsigned int i;
char c[4];
} lint;
lint.i = 0x01020304;
endian = (lint.c[0] == '\x04') ? -1 : 1;
}
odd_nails = (nails % 8u);
odd_nail_mask = 0xff;
for (i = 0; i < odd_nails; ++i) {
odd_nail_mask ^= (unsigned char)(1u << (7u - i));
}
nail_bytes = nails / 8u;
bits = (size_t)mp_count_bits(&t);
count = (bits / ((size * 8u) - nails)) + (((bits % ((size * 8u) - nails)) != 0u) ? 1u : 0u);
for (i = 0; i < count; ++i) {
for (j = 0; j < size; ++j) {
unsigned char *byte = (unsigned char *)rop +
(((order == -1) ? i : ((count - 1u) - i)) * size) +
((endian == -1) ? j : ((size - 1u) - j));
if (j >= (size - nail_bytes)) {
*byte = 0;
continue;
}
*byte = (unsigned char)((j == ((size - nail_bytes) - 1u)) ? (t.dp[0] & odd_nail_mask) : (t.dp[0] & 0xFFuL));
if ((result = mp_div_2d(&t, (j == ((size - nail_bytes) - 1u)) ? (int)(8u - odd_nails) : 8, &t, NULL)) != MP_OKAY) {
mp_clear(&t);
return result;
}
}
}
mp_clear(&t);
if (countp != NULL) {
*countp = count;
}
return MP_OKAY;
}
#endif
/* ref: HEAD -> master, tag: v1.1.0 */
/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
/* commit time: 2019-01-28 20:32:32 +0100 */
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