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-rw-r--r--libtommath/bn_s_mp_sub.c101
1 files changed, 50 insertions, 51 deletions
diff --git a/libtommath/bn_s_mp_sub.c b/libtommath/bn_s_mp_sub.c
index 8091f4a..f61aa83 100644
--- a/libtommath/bn_s_mp_sub.c
+++ b/libtommath/bn_s_mp_sub.c
@@ -16,70 +16,69 @@
*/
/* low level subtraction (assumes |a| > |b|), HAC pp.595 Algorithm 14.9 */
-int
-s_mp_sub (mp_int * a, mp_int * b, mp_int * c)
+int s_mp_sub(mp_int *a, mp_int *b, mp_int *c)
{
- int olduse, res, min, max;
+ int olduse, res, min, max;
- /* find sizes */
- min = b->used;
- max = a->used;
+ /* find sizes */
+ min = b->used;
+ max = a->used;
- /* init result */
- if (c->alloc < max) {
- if ((res = mp_grow (c, max)) != MP_OKAY) {
- return res;
- }
- }
- olduse = c->used;
- c->used = max;
+ /* init result */
+ if (c->alloc < max) {
+ if ((res = mp_grow(c, max)) != MP_OKAY) {
+ return res;
+ }
+ }
+ olduse = c->used;
+ c->used = max;
- {
- mp_digit u, *tmpa, *tmpb, *tmpc;
- int i;
+ {
+ mp_digit u, *tmpa, *tmpb, *tmpc;
+ int i;
- /* alias for digit pointers */
- tmpa = a->dp;
- tmpb = b->dp;
- tmpc = c->dp;
+ /* alias for digit pointers */
+ tmpa = a->dp;
+ tmpb = b->dp;
+ tmpc = c->dp;
- /* set carry to zero */
- u = 0;
- for (i = 0; i < min; i++) {
- /* T[i] = A[i] - B[i] - U */
- *tmpc = (*tmpa++ - *tmpb++) - u;
+ /* set carry to zero */
+ u = 0;
+ for (i = 0; i < min; i++) {
+ /* T[i] = A[i] - B[i] - U */
+ *tmpc = (*tmpa++ - *tmpb++) - u;
- /* U = carry bit of T[i]
- * Note this saves performing an AND operation since
- * 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 >> ((mp_digit)((CHAR_BIT * sizeof(mp_digit)) - 1));
+ /* U = carry bit of T[i]
+ * Note this saves performing an AND operation since
+ * 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 >> ((mp_digit)((CHAR_BIT * sizeof(mp_digit)) - 1));
- /* Clear carry from T[i] */
- *tmpc++ &= MP_MASK;
- }
+ /* Clear carry from T[i] */
+ *tmpc++ &= MP_MASK;
+ }
- /* now copy higher words if any, e.g. if A has more digits than B */
- for (; i < max; i++) {
- /* T[i] = A[i] - U */
- *tmpc = *tmpa++ - u;
+ /* now copy higher words if any, e.g. if A has more digits than B */
+ for (; i < max; i++) {
+ /* T[i] = A[i] - U */
+ *tmpc = *tmpa++ - u;
- /* U = carry bit of T[i] */
- u = *tmpc >> ((mp_digit)((CHAR_BIT * sizeof(mp_digit)) - 1));
+ /* U = carry bit of T[i] */
+ u = *tmpc >> ((mp_digit)((CHAR_BIT * sizeof(mp_digit)) - 1));
- /* Clear carry from T[i] */
- *tmpc++ &= MP_MASK;
- }
+ /* 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;
- }
- }
+ /* clear digits above used (since we may not have grown result above) */
+ for (i = c->used; i < olduse; i++) {
+ *tmpc++ = 0;
+ }
+ }
- mp_clamp (c);
- return MP_OKAY;
+ mp_clamp(c);
+ return MP_OKAY;
}
#endif