diff options
Diffstat (limited to 'libtommath/bn_s_mp_sub.c')
| -rw-r--r-- | libtommath/bn_s_mp_sub.c | 34 |
1 files changed, 10 insertions, 24 deletions
diff --git a/libtommath/bn_s_mp_sub.c b/libtommath/bn_s_mp_sub.c index 88e44dc..5672dab 100644 --- a/libtommath/bn_s_mp_sub.c +++ b/libtommath/bn_s_mp_sub.c @@ -1,21 +1,13 @@ #include "tommath_private.h" #ifdef BN_S_MP_SUB_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 - */ +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ /* low level subtraction (assumes |a| > |b|), HAC pp.595 Algorithm 14.9 */ -int s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c) +mp_err s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c) { - int olduse, res, min, max; + int olduse, min, max; + mp_err err; /* find sizes */ min = b->used; @@ -23,8 +15,8 @@ int s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c) /* init result */ if (c->alloc < max) { - if ((res = mp_grow(c, max)) != MP_OKAY) { - return res; + if ((err = mp_grow(c, max)) != MP_OKAY) { + return err; } } olduse = c->used; @@ -50,7 +42,7 @@ int s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c) * if a carry does occur it will propagate all the way to the * MSB. As a result a single shift is enough to get the carry */ - u = *tmpc >> (((size_t)CHAR_BIT * sizeof(mp_digit)) - 1u); + u = *tmpc >> (MP_SIZEOF_BITS(mp_digit) - 1u); /* Clear carry from T[i] */ *tmpc++ &= MP_MASK; @@ -62,16 +54,14 @@ int s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c) *tmpc = *tmpa++ - u; /* U = carry bit of T[i] */ - u = *tmpc >> (((size_t)CHAR_BIT * sizeof(mp_digit)) - 1u); + u = *tmpc >> (MP_SIZEOF_BITS(mp_digit) - 1u); /* Clear carry from T[i] */ *tmpc++ &= MP_MASK; } /* clear digits above used (since we may not have grown result above) */ - for (i = c->used; i < olduse; i++) { - *tmpc++ = 0; - } + MP_ZERO_DIGITS(tmpc, olduse - c->used); } mp_clamp(c); @@ -79,7 +69,3 @@ int s_mp_sub(const mp_int *a, const mp_int *b, mp_int *c) } #endif - -/* ref: $Format:%D$ */ -/* git commit: $Format:%H$ */ -/* commit time: $Format:%ai$ */ |