diff options
author | Ulf Möller <ulf@openssl.org> | 2003-12-06 11:55:46 +0000 |
---|---|---|
committer | Ulf Möller <ulf@openssl.org> | 2003-12-06 11:55:46 +0000 |
commit | 380e145daf6afff135856afeb33b84aaed19cd4c (patch) | |
tree | 3085ad3359991cd9f4acd5f53b7da7ac9e7b4ef8 | |
parent | a9f2330f432809cafcfa65e4265f5219436f08e4 (diff) |
Add "dif" variable to clean up the loop implementations.
Submitted by: Nils Larsch
-rw-r--r-- | crypto/bn/bn_add.c | 91 |
1 files changed, 46 insertions, 45 deletions
diff --git a/crypto/bn/bn_add.c b/crypto/bn/bn_add.c index a13b8a11cb..9405163706 100644 --- a/crypto/bn/bn_add.c +++ b/crypto/bn/bn_add.c @@ -64,7 +64,7 @@ int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { const BIGNUM *tmp; - int a_neg = a->neg; + int a_neg = a->neg, ret; bn_check_top(a); bn_check_top(b); @@ -95,21 +95,17 @@ int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) return(1); } - if (!BN_uadd(r,a,b)) return(0); - if (a_neg) /* both are neg */ - r->neg=1; - else - r->neg=0; + ret = BN_uadd(r,a,b); + r->neg = a_neg; bn_check_top(r); - return(1); + return ret; } -/* unsigned add of b to a, r must be large enough */ +/* unsigned add of b to a */ int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { - register int i; - int max,min; - BN_ULONG *ap,*bp,*rp,carry,t1; + int max,min,dif; + BN_ULONG *ap,*bp,*rp,carry,t1,t2; const BIGNUM *tmp; bn_check_top(a); @@ -117,11 +113,12 @@ int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) if (a->top < b->top) { tmp=a; a=b; b=tmp; } - max=a->top; - min=b->top; + max = a->top; + min = b->top; + dif = max - min; if (bn_wexpand(r,max+1) == NULL) - return(0); + return 0; r->top=max; @@ -129,47 +126,46 @@ int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) ap=a->d; bp=b->d; rp=r->d; - carry=0; carry=bn_add_words(rp,ap,bp,min); rp+=min; ap+=min; bp+=min; - i=min; if (carry) { - while (i < max) + while (dif) { - i++; - t1= *(ap++); - if ((*(rp++)=(t1+1)&BN_MASK2) >= t1) + dif--; + t1 = *(ap++); + t2 = (t1+1) & BN_MASK2; + *(rp++) = t2; + if (t2) { carry=0; break; } } - if ((i >= max) && carry) + if (carry) { - *(rp++)=1; + /* carry != 0 => dif == 0 */ + *rp = 1; r->top++; } } - if (rp != ap) - { - for (; i<max; i++) - *(rp++)= *(ap++); - } - /* memcpy(rp,ap,sizeof(*ap)*(max-i));*/ + if (dif && rp != ap) + while (dif--) + /* copy remaining words if ap != rp */ + *(rp++) = *(ap++); r->neg = 0; bn_check_top(r); - return(1); + return 1; } /* unsigned subtraction of b from a, a must be larger than b. */ int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { - int max,min; + int max,min,dif; register BN_ULONG t1,t2,*ap,*bp,*rp; int i,carry; #if defined(IRIX_CC_BUG) && !defined(LINT) @@ -179,14 +175,16 @@ int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) bn_check_top(a); bn_check_top(b); - if (a->top < b->top) /* hmm... should not be happening */ + max = a->top; + min = b->top; + dif = max - min; + + if (dif < 0) /* hmm... should not be happening */ { BNerr(BN_F_BN_USUB,BN_R_ARG2_LT_ARG3); return(0); } - max=a->top; - min=b->top; if (bn_wexpand(r,max) == NULL) return(0); ap=a->d; @@ -195,7 +193,7 @@ int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) #if 1 carry=0; - for (i=0; i<min; i++) + for (i = min; i != 0; i--) { t1= *(ap++); t2= *(bp++); @@ -219,17 +217,20 @@ int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) ap+=min; bp+=min; rp+=min; - i=min; #endif if (carry) /* subtracted */ { - while (i < max) + if (!dif) + /* error: a < b */ + return 0; + while (dif) { - i++; - t1= *(ap++); - t2=(t1-1)&BN_MASK2; - *(rp++)=t2; - if (t1 > t2) break; + dif--; + t1 = *(ap++); + t2 = (t1-1)&BN_MASK2; + *(rp++) = t2; + if (t1) + break; } } #if 0 @@ -239,13 +240,13 @@ int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b) { for (;;) { - if (i++ >= max) break; + if (!dif--) break; rp[0]=ap[0]; - if (i++ >= max) break; + if (!dif--) break; rp[1]=ap[1]; - if (i++ >= max) break; + if (!dif--) break; rp[2]=ap[2]; - if (i++ >= max) break; + if (!dif--) break; rp[3]=ap[3]; rp+=4; ap+=4; |