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Reduce the stack size required by fp_exptmod slightly. On Perf branch.

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git-svn-id: svn://10.0.0.236/branches/NSS_PERFORMANCE_HACKS_BRANCH@174744 18797224-902f-48f8-a5cc-f745e15eee43
This commit is contained in:
nelsonb%netscape.com
2005-06-17 02:07:16 +00:00
parent a040adc3f1
commit 519ea8041b
1 changed files with 16 additions and 13 deletions
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29
mozilla/security/nss/lib/freebl/tfm/fp_exptmod.c
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@@ -9,7 +9,7 @@
*/
#include <tfm.h>
/* y = g**x (mod b)
/* y = g**x (mod P)
* Some restrictions... x must be positive and < b
*/
static int _fp_exptmod(fp_int * G, fp_int * X, fp_int * P, fp_int * Y)
@@ -168,23 +168,26 @@ static int _fp_exptmod(fp_int * G, fp_int * X, fp_int * P, fp_int * Y)
return FP_OKAY;
}
/* not static, to avoid inlining */
int _fp_negexptmod(fp_int * G, fp_int * X, fp_int * P, fp_int * Y)
{
fp_int tmpG, tmpX;
int err;
/* copy G and invmod it */
fp_abs(X, &tmpX);
if ((err = fp_invmod(G, P, &tmpG)) != FP_OKAY) {
return err;
}
err = _fp_exptmod(&tmpG, &tmpX, P, Y);
return err;
}
int fp_exptmod(fp_int * G, fp_int * X, fp_int * P, fp_int * Y)
{
fp_int tmp;
int err;
/* is X negative? */
if (X->sign == FP_NEG) {
/* yes, copy G and invmod it */
fp_copy(G, &tmp);
if ((err = fp_invmod(&tmp, P, &tmp)) != FP_OKAY) {
return err;
}
X->sign = FP_ZPOS;
err = _fp_exptmod(&tmp, X, P, Y);
X->sign = FP_NEG;
return err;
return _fp_negexptmod(G, X, P, Y);
} else {
/* Positive exponent so just exptmod */
return _fp_exptmod(G, X, P, Y);