summaryrefslogtreecommitdiffstats
path: root/libtommath/bn_mp_pack.c
diff options
context:
space:
mode:
Diffstat (limited to 'libtommath/bn_mp_pack.c')
-rw-r--r--libtommath/bn_mp_pack.c69
1 files changed, 69 insertions, 0 deletions
diff --git a/libtommath/bn_mp_pack.c b/libtommath/bn_mp_pack.c
new file mode 100644
index 0000000..6e00b6f
--- /dev/null
+++ b/libtommath/bn_mp_pack.c
@@ -0,0 +1,69 @@
+#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