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#include "tommath_private.h"
#ifdef BN_MP_PACK_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* based on gmp's mpz_export.
* see http://gmplib.org/manual/Integer-Import-and-Export.html
*/
mp_err mp_pack(void *rop, size_t maxcount, size_t *written, mp_order order, size_t size,
mp_endian endian, size_t nails, const mp_int *op)
{
mp_err err;
size_t odd_nails, nail_bytes, i, j, count;
unsigned char odd_nail_mask;
mp_int t;
count = mp_pack_count(op, nails, size);
if (count > maxcount) {
return MP_BUF;
}
if ((err = mp_init_copy(&t, op)) != MP_OKAY) {
return err;
}
if (endian == MP_NATIVE_ENDIAN) {
MP_GET_ENDIANNESS(endian);
}
odd_nails = (nails % 8u);
odd_nail_mask = 0xff;
for (i = 0u; i < odd_nails; ++i) {
odd_nail_mask ^= (unsigned char)(1u << (7u - i));
}
nail_bytes = nails / 8u;
for (i = 0u; i < count; ++i) {
for (j = 0u; j < size; ++j) {
unsigned char *byte = (unsigned char *)rop +
(((order == MP_LSB_FIRST) ? i : ((count - 1u) - i)) * size) +
((endian == MP_LITTLE_ENDIAN) ? 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 ((err = mp_div_2d(&t, (j == ((size - nail_bytes) - 1u)) ? (int)(8u - odd_nails) : 8, &t, NULL)) != MP_OKAY) {
goto LBL_ERR;
}
}
}
if (written != NULL) {
*written = count;
}
err = MP_OKAY;
LBL_ERR:
mp_clear(&t);
return err;
}
#endif
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