--- /dev/null
+/* crypto/bn/bn_add.c */
+/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
+ * All rights reserved.
+ *
+ * This package is an SSL implementation written
+ * by Eric Young (eay@cryptsoft.com).
+ * The implementation was written so as to conform with Netscapes SSL.
+ *
+ * This library is free for commercial and non-commercial use as long as
+ * the following conditions are aheared to. The following conditions
+ * apply to all code found in this distribution, be it the RC4, RSA,
+ * lhash, DES, etc., code; not just the SSL code. The SSL documentation
+ * included with this distribution is covered by the same copyright terms
+ * except that the holder is Tim Hudson (tjh@cryptsoft.com).
+ *
+ * Copyright remains Eric Young's, and as such any Copyright notices in
+ * the code are not to be removed.
+ * If this package is used in a product, Eric Young should be given attribution
+ * as the author of the parts of the library used.
+ * This can be in the form of a textual message at program startup or
+ * in documentation (online or textual) provided with the package.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * "This product includes cryptographic software written by
+ * Eric Young (eay@cryptsoft.com)"
+ * The word 'cryptographic' can be left out if the rouines from the library
+ * being used are not cryptographic related :-).
+ * 4. If you include any Windows specific code (or a derivative thereof) from
+ * the apps directory (application code) you must include an acknowledgement:
+ * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * The licence and distribution terms for any publically available version or
+ * derivative of this code cannot be changed. i.e. this code cannot simply be
+ * copied and put under another distribution licence
+ * [including the GNU Public Licence.]
+ */
+
+#include <stdio.h>
+#include "cryptlib.h"
+#include "bn_lcl.h"
+
+/* r can == a or b */
+int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
+ {
+ const BIGNUM *tmp;
+ int a_neg = a->neg, ret;
+
+ bn_check_top(a);
+ bn_check_top(b);
+
+ /* a + b a+b
+ * a + -b a-b
+ * -a + b b-a
+ * -a + -b -(a+b)
+ */
+ if (a_neg ^ b->neg)
+ {
+ /* only one is negative */
+ if (a_neg)
+ { tmp=a; a=b; b=tmp; }
+
+ /* we are now a - b */
+
+ 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);
+ }
+
+ ret = BN_uadd(r,a,b);
+ r->neg = a_neg;
+ bn_check_top(r);
+ return ret;
+ }
+
+/* unsigned add of b to a */
+int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
+ {
+ int max,min,dif;
+ BN_ULONG *ap,*bp,*rp,carry,t1,t2;
+ const 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;
+ dif = max - min;
+
+ if (bn_wexpand(r,max+1) == NULL)
+ return 0;
+
+ r->top=max;
+
+
+ ap=a->d;
+ bp=b->d;
+ rp=r->d;
+
+ carry=bn_add_words(rp,ap,bp,min);
+ rp+=min;
+ ap+=min;
+ bp+=min;
+
+ if (carry)
+ {
+ while (dif)
+ {
+ dif--;
+ t1 = *(ap++);
+ t2 = (t1+1) & BN_MASK2;
+ *(rp++) = t2;
+ if (t2)
+ {
+ carry=0;
+ break;
+ }
+ }
+ if (carry)
+ {
+ /* carry != 0 => dif == 0 */
+ *rp = 1;
+ r->top++;
+ }
+ }
+ if (dif && rp != ap)
+ while (dif--)
+ /* copy remaining words if ap != rp */
+ *(rp++) = *(ap++);
+ r->neg = 0;
+ bn_check_top(r);
+ 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,dif;
+ 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);
+
+ 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);
+ }
+
+ if (bn_wexpand(r,max) == NULL) return(0);
+
+ ap=a->d;
+ bp=b->d;
+ rp=r->d;
+
+#if 1
+ carry=0;
+ for (i = min; i != 0; 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;
+#endif
+ if (carry) /* subtracted */
+ {
+ if (!dif)
+ /* error: a < b */
+ return 0;
+ while (dif)
+ {
+ dif--;
+ t1 = *(ap++);
+ t2 = (t1-1)&BN_MASK2;
+ *(rp++) = t2;
+ if (t1)
+ break;
+ }
+ }
+#if 0
+ memcpy(rp,ap,sizeof(*rp)*(max-i));
+#else
+ if (rp != ap)
+ {
+ for (;;)
+ {
+ if (!dif--) break;
+ rp[0]=ap[0];
+ if (!dif--) break;
+ rp[1]=ap[1];
+ if (!dif--) break;
+ rp[2]=ap[2];
+ if (!dif--) break;
+ rp[3]=ap[3];
+ rp+=4;
+ ap+=4;
+ }
+ }
+#endif
+
+ r->top=max;
+ r->neg=0;
+ bn_correct_top(r);
+ return(1);
+ }
+
+int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
+ {
+ int max;
+ int add=0,neg=0;
+ const 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;
+ }
+ bn_check_top(r);
+ return(1);
+ }
+
projects / cassiopeia.git / blobdiff