#include "cryptlib.h"
#include "bn_lcl.h"
+
/* The old slow way */
#if 0
int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d,
#else
-#if !defined(NO_ASM) && !defined(NO_INLINE_ASM) && !defined(PEDANTIC) && !defined(BN_DIV3W)
+#if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM) \
+ && !defined(PEDANTIC) && !defined(BN_DIV3W)
# if defined(__GNUC__) && __GNUC__>=2
-# if defined(__i386)
+# if defined(__i386) || defined (__i386__)
/*
* There were two reasons for implementing this template:
* - GNU C generates a call to a function (__udivdi3 to be exact)
# define REMAINDER_IS_ALREADY_CALCULATED
# endif /* __<cpu> */
# endif /* __GNUC__ */
-#endif /* NO_ASM */
+#endif /* OPENSSL_NO_ASM */
+
+/* BN_div computes dv := num / divisor, rounding towards zero, and sets up
+ * rm such that dv*divisor + rm = num holds.
+ * Thus:
+ * dv->neg == num->neg ^ divisor->neg (unless the result is zero)
+ * rm->neg == num->neg (unless the remainder is zero)
+ * If 'dv' or 'rm' is NULL, the respective value is not returned.
+ */
int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
BN_CTX *ctx)
{
BN_CTX_start(ctx);
tmp=BN_CTX_get(ctx);
- tmp->neg=0;
snum=BN_CTX_get(ctx);
sdiv=BN_CTX_get(ctx);
if (dv == NULL)
res=BN_CTX_get(ctx);
else res=dv;
- if (res == NULL) goto err;
+ if (sdiv == NULL || res == NULL) goto err;
+ tmp->neg=0;
/* First we normalise the numbers */
norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
- BN_lshift(sdiv,divisor,norm_shift);
+ if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err;
sdiv->neg=0;
norm_shift+=BN_BITS2;
- BN_lshift(snum,num,norm_shift);
+ if (!(BN_lshift(snum,num,norm_shift))) goto err;
snum->neg=0;
div_n=sdiv->top;
num_n=snum->top;
}
else
res->top--;
+ if (res->top == 0)
+ res->neg = 0;
resp--;
for (i=0; i<loop-1; i++)
{
BN_ULONG q,l0;
-#ifdef BN_DIV3W
+#if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
+ BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG);
q=bn_div_3_words(wnump,d1,d0);
#else
BN_ULONG n0,n1,rem=0;
tmp->top=j;
j=wnum.top;
- BN_sub(&wnum,&wnum,tmp);
+ if (!BN_sub(&wnum,&wnum,tmp)) goto err;
snum->top=snum->top+wnum.top-j;
{
q--;
j=wnum.top;
- BN_add(&wnum,&wnum,sdiv);
+ if (!BN_add(&wnum,&wnum,sdiv)) goto err;
snum->top+=wnum.top-j;
}
*(resp--)=q;
}
if (rm != NULL)
{
+ /* Keep a copy of the neg flag in num because if rm==num
+ * BN_rshift() will overwrite it.
+ */
+ int neg = num->neg;
BN_rshift(rm,snum,norm_shift);
- rm->neg=num->neg;
+ if (!BN_is_zero(rm))
+ rm->neg = neg;
}
BN_CTX_end(ctx);
return(1);
}
#endif
-
-/* rem != m */
-int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
- {
-#if 0 /* The old slow way */
- int i,nm,nd;
- BIGNUM *dv;
-
- if (BN_ucmp(m,d) < 0)
- return((BN_copy(rem,m) == NULL)?0:1);
-
- BN_CTX_start(ctx);
- dv=BN_CTX_get(ctx);
-
- if (!BN_copy(rem,m)) goto err;
-
- nm=BN_num_bits(rem);
- nd=BN_num_bits(d);
- if (!BN_lshift(dv,d,nm-nd)) goto err;
- for (i=nm-nd; i>=0; i--)
- {
- if (BN_cmp(rem,dv) >= 0)
- {
- if (!BN_sub(rem,rem,dv)) goto err;
- }
- if (!BN_rshift1(dv,dv)) goto err;
- }
- BN_CTX_end(ctx);
- return(1);
- err:
- BN_CTX_end(ctx);
- return(0);
-#else
- return(BN_div(NULL,rem,m,d,ctx));
-#endif
- }
-