Commit b1f9bff192798c83f6de40f5ca067d4036aa0b3e
2019-10-29T20:21:22
simplifications: invmod
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diff --git a/s_mp_invmod_fast.c b/s_mp_invmod_fast.c
index ed1fc4a..46cf0d6 100644
--- a/s_mp_invmod_fast.c
+++ b/s_mp_invmod_fast.c
@@ -42,51 +42,49 @@ mp_err s_mp_invmod_fast(const mp_int *a, const mp_int *b, mp_int *c)
if ((err = mp_copy(&y, &v)) != MP_OKAY) goto LBL_ERR;
mp_set(&D, 1uL);
-top:
- /* 4. while u is even do */
- while (mp_iseven(&u)) {
- /* 4.1 u = u/2 */
- if ((err = mp_div_2(&u, &u)) != MP_OKAY) goto LBL_ERR;
-
- /* 4.2 if B is odd then */
- if (mp_isodd(&B)) {
- if ((err = mp_sub(&B, &x, &B)) != MP_OKAY) goto LBL_ERR;
+ do {
+ /* 4. while u is even do */
+ while (mp_iseven(&u)) {
+ /* 4.1 u = u/2 */
+ if ((err = mp_div_2(&u, &u)) != MP_OKAY) goto LBL_ERR;
+
+ /* 4.2 if B is odd then */
+ if (mp_isodd(&B)) {
+ if ((err = mp_sub(&B, &x, &B)) != MP_OKAY) goto LBL_ERR;
+ }
+ /* B = B/2 */
+ if ((err = mp_div_2(&B, &B)) != MP_OKAY) goto LBL_ERR;
}
- /* B = B/2 */
- if ((err = mp_div_2(&B, &B)) != MP_OKAY) goto LBL_ERR;
- }
-
- /* 5. while v is even do */
- while (mp_iseven(&v)) {
- /* 5.1 v = v/2 */
- if ((err = mp_div_2(&v, &v)) != MP_OKAY) goto LBL_ERR;
- /* 5.2 if D is odd then */
- if (mp_isodd(&D)) {
- /* D = (D-x)/2 */
- if ((err = mp_sub(&D, &x, &D)) != MP_OKAY) goto LBL_ERR;
+ /* 5. while v is even do */
+ while (mp_iseven(&v)) {
+ /* 5.1 v = v/2 */
+ if ((err = mp_div_2(&v, &v)) != MP_OKAY) goto LBL_ERR;
+
+ /* 5.2 if D is odd then */
+ if (mp_isodd(&D)) {
+ /* D = (D-x)/2 */
+ if ((err = mp_sub(&D, &x, &D)) != MP_OKAY) goto LBL_ERR;
+ }
+ /* D = D/2 */
+ if ((err = mp_div_2(&D, &D)) != MP_OKAY) goto LBL_ERR;
}
- /* D = D/2 */
- if ((err = mp_div_2(&D, &D)) != MP_OKAY) goto LBL_ERR;
- }
- /* 6. if u >= v then */
- if (mp_cmp(&u, &v) != MP_LT) {
- /* u = u - v, B = B - D */
- if ((err = mp_sub(&u, &v, &u)) != MP_OKAY) goto LBL_ERR;
+ /* 6. if u >= v then */
+ if (mp_cmp(&u, &v) != MP_LT) {
+ /* u = u - v, B = B - D */
+ if ((err = mp_sub(&u, &v, &u)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_sub(&B, &D, &B)) != MP_OKAY) goto LBL_ERR;
- } else {
- /* v - v - u, D = D - B */
- if ((err = mp_sub(&v, &u, &v)) != MP_OKAY) goto LBL_ERR;
+ if ((err = mp_sub(&B, &D, &B)) != MP_OKAY) goto LBL_ERR;
+ } else {
+ /* v - v - u, D = D - B */
+ if ((err = mp_sub(&v, &u, &v)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_sub(&D, &B, &D)) != MP_OKAY) goto LBL_ERR;
- }
+ if ((err = mp_sub(&D, &B, &D)) != MP_OKAY) goto LBL_ERR;
+ }
- /* if not zero goto step 4 */
- if (!mp_iszero(&u)) {
- goto top;
- }
+ /* if not zero goto step 4 */
+ } while (!mp_iszero(&u));
/* now a = C, b = D, gcd == g*v */
diff --git a/s_mp_invmod_slow.c b/s_mp_invmod_slow.c
index 28cd6cd..7d07a14 100644
--- a/s_mp_invmod_slow.c
+++ b/s_mp_invmod_slow.c
@@ -36,60 +36,58 @@ mp_err s_mp_invmod_slow(const mp_int *a, const mp_int *b, mp_int *c)
mp_set(&A, 1uL);
mp_set(&D, 1uL);
-top:
- /* 4. while u is even do */
- while (mp_iseven(&u)) {
- /* 4.1 u = u/2 */
- if ((err = mp_div_2(&u, &u)) != MP_OKAY) goto LBL_ERR;
-
- /* 4.2 if A or B is odd then */
- if (mp_isodd(&A) || mp_isodd(&B)) {
- /* A = (A+y)/2, B = (B-x)/2 */
- if ((err = mp_add(&A, &y, &A)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_sub(&B, &x, &B)) != MP_OKAY) goto LBL_ERR;
+ do {
+ /* 4. while u is even do */
+ while (mp_iseven(&u)) {
+ /* 4.1 u = u/2 */
+ if ((err = mp_div_2(&u, &u)) != MP_OKAY) goto LBL_ERR;
+
+ /* 4.2 if A or B is odd then */
+ if (mp_isodd(&A) || mp_isodd(&B)) {
+ /* A = (A+y)/2, B = (B-x)/2 */
+ if ((err = mp_add(&A, &y, &A)) != MP_OKAY) goto LBL_ERR;
+ if ((err = mp_sub(&B, &x, &B)) != MP_OKAY) goto LBL_ERR;
+ }
+ /* A = A/2, B = B/2 */
+ if ((err = mp_div_2(&A, &A)) != MP_OKAY) goto LBL_ERR;
+ if ((err = mp_div_2(&B, &B)) != MP_OKAY) goto LBL_ERR;
}
- /* A = A/2, B = B/2 */
- if ((err = mp_div_2(&A, &A)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_div_2(&B, &B)) != MP_OKAY) goto LBL_ERR;
- }
-
- /* 5. while v is even do */
- while (mp_iseven(&v)) {
- /* 5.1 v = v/2 */
- if ((err = mp_div_2(&v, &v)) != MP_OKAY) goto LBL_ERR;
- /* 5.2 if C or D is odd then */
- if (mp_isodd(&C) || mp_isodd(&D)) {
- /* C = (C+y)/2, D = (D-x)/2 */
- if ((err = mp_add(&C, &y, &C)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_sub(&D, &x, &D)) != MP_OKAY) goto LBL_ERR;
+ /* 5. while v is even do */
+ while (mp_iseven(&v)) {
+ /* 5.1 v = v/2 */
+ if ((err = mp_div_2(&v, &v)) != MP_OKAY) goto LBL_ERR;
+
+ /* 5.2 if C or D is odd then */
+ if (mp_isodd(&C) || mp_isodd(&D)) {
+ /* C = (C+y)/2, D = (D-x)/2 */
+ if ((err = mp_add(&C, &y, &C)) != MP_OKAY) goto LBL_ERR;
+ if ((err = mp_sub(&D, &x, &D)) != MP_OKAY) goto LBL_ERR;
+ }
+ /* C = C/2, D = D/2 */
+ if ((err = mp_div_2(&C, &C)) != MP_OKAY) goto LBL_ERR;
+ if ((err = mp_div_2(&D, &D)) != MP_OKAY) goto LBL_ERR;
}
- /* C = C/2, D = D/2 */
- if ((err = mp_div_2(&C, &C)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_div_2(&D, &D)) != MP_OKAY) goto LBL_ERR;
- }
- /* 6. if u >= v then */
- if (mp_cmp(&u, &v) != MP_LT) {
- /* u = u - v, A = A - C, B = B - D */
- if ((err = mp_sub(&u, &v, &u)) != MP_OKAY) goto LBL_ERR;
+ /* 6. if u >= v then */
+ if (mp_cmp(&u, &v) != MP_LT) {
+ /* u = u - v, A = A - C, B = B - D */
+ if ((err = mp_sub(&u, &v, &u)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_sub(&A, &C, &A)) != MP_OKAY) goto LBL_ERR;
+ if ((err = mp_sub(&A, &C, &A)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_sub(&B, &D, &B)) != MP_OKAY) goto LBL_ERR;
- } else {
- /* v - v - u, C = C - A, D = D - B */
- if ((err = mp_sub(&v, &u, &v)) != MP_OKAY) goto LBL_ERR;
+ if ((err = mp_sub(&B, &D, &B)) != MP_OKAY) goto LBL_ERR;
+ } else {
+ /* v - v - u, C = C - A, D = D - B */
+ if ((err = mp_sub(&v, &u, &v)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_sub(&C, &A, &C)) != MP_OKAY) goto LBL_ERR;
+ if ((err = mp_sub(&C, &A, &C)) != MP_OKAY) goto LBL_ERR;
- if ((err = mp_sub(&D, &B, &D)) != MP_OKAY) goto LBL_ERR;
- }
+ if ((err = mp_sub(&D, &B, &D)) != MP_OKAY) goto LBL_ERR;
+ }
- /* if not zero goto step 4 */
- if (!mp_iszero(&u)) {
- goto top;
- }
+ /* if not zero goto step 4 */
+ } while (!mp_iszero(&u));
/* now a = C, b = D, gcd == g*v */
@@ -111,7 +109,7 @@ top:
/* C is now the inverse */
mp_exch(&C, c);
- err = MP_OKAY;
+
LBL_ERR:
mp_clear_multi(&x, &y, &u, &v, &A, &B, &C, &D, NULL);
return err;