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author | jan.nijtmans <nijtmans@users.sourceforge.net> | 2019-06-13 19:07:13 (GMT) |
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committer | jan.nijtmans <nijtmans@users.sourceforge.net> | 2019-06-13 19:07:13 (GMT) |
commit | 505f963287b050bd46871d4659cebc65986ca5ac (patch) | |
tree | 853ad3262ab07f7c5755e76b8154f36f24608014 /libtommath/bn_s_mp_balance_mul.c | |
parent | 689987ea924a8fded1801777c1a14ab1205fa826 (diff) | |
download | tcl-505f963287b050bd46871d4659cebc65986ca5ac.zip tcl-505f963287b050bd46871d4659cebc65986ca5ac.tar.gz tcl-505f963287b050bd46871d4659cebc65986ca5ac.tar.bz2 |
Update to latest libtommath's "develop" branch. On the way to 1.2.0
Diffstat (limited to 'libtommath/bn_s_mp_balance_mul.c')
-rw-r--r-- | libtommath/bn_s_mp_balance_mul.c | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/libtommath/bn_s_mp_balance_mul.c b/libtommath/bn_s_mp_balance_mul.c new file mode 100644 index 0000000..efc1809 --- /dev/null +++ b/libtommath/bn_s_mp_balance_mul.c @@ -0,0 +1,79 @@ +#include "tommath_private.h" +#ifdef BN_S_MP_BALANCE_MUL_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ + +/* single-digit multiplication with the smaller number as the single-digit */ +mp_err s_mp_balance_mul(const mp_int *a, const mp_int *b, mp_int *c) +{ + int count, len_a, len_b, nblocks, i, j, bsize; + mp_int a0, tmp, A, B, r; + mp_err err; + + len_a = a->used; + len_b = b->used; + + nblocks = MP_MAX(a->used, b->used) / MP_MIN(a->used, b->used); + bsize = MP_MIN(a->used, b->used) ; + + if ((err = mp_init_size(&a0, bsize + 2)) != MP_OKAY) { + return err; + } + if ((err = mp_init_multi(&tmp, &r, NULL)) != MP_OKAY) { + mp_clear(&a0); + return err; + } + + /* Make sure that A is the larger one*/ + if (len_a < len_b) { + B = *a; + A = *b; + } else { + A = *a; + B = *b; + } + + for (i = 0, j=0; i < nblocks; i++) { + /* Cut a slice off of a */ + a0.used = 0; + for (count = 0; count < bsize; count++) { + a0.dp[count] = A.dp[ j++ ]; + a0.used++; + } + /* Multiply with b */ + if ((err = mp_mul(&a0, &B, &tmp)) != MP_OKAY) { + goto LBL_ERR; + } + /* Shift tmp to the correct position */ + if ((err = mp_lshd(&tmp, bsize * i)) != MP_OKAY) { + goto LBL_ERR; + } + /* Add to output. No carry needed */ + if ((err = mp_add(&r, &tmp, &r)) != MP_OKAY) { + goto LBL_ERR; + } + } + /* The left-overs; there are always left-overs */ + if (j < A.used) { + a0.used = 0; + for (count = 0; j < A.used; count++) { + a0.dp[count] = A.dp[ j++ ]; + a0.used++; + } + if ((err = mp_mul(&a0, &B, &tmp)) != MP_OKAY) { + goto LBL_ERR; + } + if ((err = mp_lshd(&tmp, bsize * i)) != MP_OKAY) { + goto LBL_ERR; + } + if ((err = mp_add(&r, &tmp, &r)) != MP_OKAY) { + goto LBL_ERR; + } + } + + mp_exch(&r,c); +LBL_ERR: + mp_clear_multi(&a0, &tmp, &r,NULL); + return err; +} +#endif |