/* TomsFastMath, a fast ISO C bignum library.
  * 
  * This project is meant to fill in where LibTomMath
  * falls short.  That is speed ;-)
  *
  * This project is public domain and free for all purposes.
  * 
  * Tom St Denis, tomstdenis@gmail.com
  */
 #include "bignum_fast.h"
 
 /* c = a - b */
 void fp_sub(fp_int *a, fp_int *b, fp_int *c)
 {
   int     sa, sb;
 
   sa = a->sign;
   sb = b->sign;
 
   if (sa != sb) {
     /* subtract a negative from a positive, OR */
     /* subtract a positive from a negative. */
     /* In either case, ADD their magnitudes, */
     /* and use the sign of the first number. */
     c->sign = sa;
     s_fp_add (a, b, c);
   } else {
     /* subtract a positive from a positive, OR */
     /* subtract a negative from a negative. */
     /* First, take the difference between their */
     /* magnitudes, then... */
     if (fp_cmp_mag (a, b) != FP_LT) {
       /* Copy the sign from the first */
       c->sign = sa;
       /* The first has a larger or equal magnitude */
       s_fp_sub (a, b, c);
     } else {
       /* The result has the *opposite* sign from */
       /* the first number. */
       c->sign = (sa == FP_ZPOS) ? FP_NEG : FP_ZPOS;
       /* The second has a larger magnitude */
       s_fp_sub (b, a, c);
     }
   }
 }
 
 
 /* $Source: /cvs/libtom/tomsfastmath/src/addsub/fp_sub.c,v $ */
 /* $Revision: 1.1 $ */
 /* $Date: 2006/12/31 21:25:53 $ */