diff options
Diffstat (limited to 'crypto/bn/bn_add.c')
| -rw-r--r-- | crypto/bn/bn_add.c | 192 |
1 files changed, 172 insertions, 20 deletions
diff --git a/crypto/bn/bn_add.c b/crypto/bn/bn_add.c index efb2e312e8..27b781a367 100644 --- a/crypto/bn/bn_add.c +++ b/crypto/bn/bn_add.c @@ -66,9 +66,11 @@ BIGNUM *r; BIGNUM *a; BIGNUM *b; { - int i; BIGNUM *tmp; + bn_check_top(a); + bn_check_top(b); + /* a + b a+b * a + -b a-b * -a + b b-a @@ -84,14 +86,12 @@ BIGNUM *b; if (BN_ucmp(a,b) < 0) { - if (bn_wexpand(r,b->top) == NULL) return(0); - bn_qsub(r,b,a); + if (!BN_usub(r,b,a)) return(0); r->neg=1; } else { - if (bn_wexpand(r,a->top) == NULL) return(0); - bn_qsub(r,a,b); + if (!BN_usub(r,a,b)) return(0); r->neg=0; } return(1); @@ -102,23 +102,12 @@ BIGNUM *b; else r->neg=0; - i=(a->top > b->top); - - if (i) - { - if (bn_wexpand(r,a->top+1) == NULL) return(0); - bn_qadd(r,a,b); - } - else - { - if (bn_wexpand(r,b->top+1) == NULL) return(0); - bn_qadd(r,b,a); - } + if (!BN_uadd(r,a,b)) return(0); return(1); } /* unsigned add of b to a, r must be large enough */ -void bn_qadd(r,a,b) +int BN_uadd(r,a,b) BIGNUM *r; BIGNUM *a; BIGNUM *b; @@ -126,11 +115,22 @@ BIGNUM *b; register int i; int max,min; BN_ULONG *ap,*bp,*rp,carry,t1; + BIGNUM *tmp; + + bn_check_top(a); + bn_check_top(b); + if (a->top < b->top) + { tmp=a; a=b; b=tmp; } max=a->top; min=b->top; + + if (bn_wexpand(r,max+1) == NULL) + return(0); + r->top=max; + ap=a->d; bp=b->d; rp=r->d; @@ -160,8 +160,160 @@ BIGNUM *b; r->top++; } } - for (; i<max; i++) - *(rp++)= *(ap++); + if (rp != ap) + { + for (; i<max; i++) + *(rp++)= *(ap++); + } /* memcpy(rp,ap,sizeof(*ap)*(max-i));*/ + return(1); + } + +/* unsigned subtraction of b from a, a must be larger than b. */ +int BN_usub(r, a, b) +BIGNUM *r; +BIGNUM *a; +BIGNUM *b; + { + int max,min,ret=1; + register BN_ULONG t1,t2,*ap,*bp,*rp; + int i,carry; +#if defined(IRIX_CC_BUG) && !defined(LINT) + int dummy; +#endif + + bn_check_top(a); + bn_check_top(b); + + if (a->top < b->top) /* 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; + bp=b->d; + rp=r->d; + +#if 1 + carry=0; + for (i=0; i<min; i++) + { + t1= *(ap++); + t2= *(bp++); + if (carry) + { + carry=(t1 <= t2); + t1=(t1-t2-1)&BN_MASK2; + } + else + { + carry=(t1 < t2); + t1=(t1-t2)&BN_MASK2; + } +#if defined(IRIX_CC_BUG) && !defined(LINT) + dummy=t1; +#endif + *(rp++)=t1&BN_MASK2; + } +#else + carry=bn_sub_words(rp,ap,bp,min); + ap+=min; + bp+=min; + rp+=min; + i=min; +#endif + if (carry) /* subtracted */ + { + while (i < max) + { + i++; + t1= *(ap++); + t2=(t1-1)&BN_MASK2; + *(rp++)=t2; + if (t1 > t2) break; + } + } +#if 0 + memcpy(rp,ap,sizeof(*rp)*(max-i)); +#else + if (rp != ap) + { + for (;;) + { + if (i++ >= max) break; + rp[0]=ap[0]; + if (i++ >= max) break; + rp[1]=ap[1]; + if (i++ >= max) break; + rp[2]=ap[2]; + if (i++ >= max) break; + rp[3]=ap[3]; + rp+=4; + ap+=4; + } + } +#endif + + r->top=max; + bn_fix_top(r); + return(1); + } + +int BN_sub(r, a, b) +BIGNUM *r; +BIGNUM *a; +BIGNUM *b; + { + int max; + int add=0,neg=0; + BIGNUM *tmp; + + bn_check_top(a); + bn_check_top(b); + + /* a - b a-b + * a - -b a+b + * -a - b -(a+b) + * -a - -b b-a + */ + if (a->neg) + { + if (b->neg) + { tmp=a; a=b; b=tmp; } + else + { add=1; neg=1; } + } + else + { + if (b->neg) { add=1; neg=0; } + } + + if (add) + { + if (!BN_uadd(r,a,b)) return(0); + r->neg=neg; + return(1); + } + + /* We are actually doing a - b :-) */ + + max=(a->top > b->top)?a->top:b->top; + if (bn_wexpand(r,max) == NULL) return(0); + if (BN_ucmp(a,b) < 0) + { + if (!BN_usub(r,b,a)) return(0); + r->neg=1; + } + else + { + if (!BN_usub(r,a,b)) return(0); + r->neg=0; + } + return(1); } |