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annotate tomsfastmath/src/addsub/fp_add.c @ 643:a362b62d38b2 dropbear-tfm

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Add tomsfastmath from git rev bfa4582842bc3bab42e4be4aed5703437049502a with Makefile.in renamed
author Matt Johnston <matt@ucc.asn.au>
date Wed, 23 Nov 2011 18:10:20 +0700
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a362b62d38b2 Add tomsfastmath from git rev bfa4582842bc3bab42e4be4aed5703437049502a
Matt Johnston <matt@ucc.asn.au>
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1 /* TomsFastMath, a fast ISO C bignum library.
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2 *
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3 * This project is meant to fill in where LibTomMath
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4 * falls short. That is speed ;-)
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5 *
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6 * This project is public domain and free for all purposes.
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7 *
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8 * Tom St Denis, [email protected]
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9 */
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10 #include <tfm.h>
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12 void fp_add(fp_int *a, fp_int *b, fp_int *c)
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13 {
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14 int sa, sb;
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16 /* get sign of both inputs */
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17 sa = a->sign;
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18 sb = b->sign;
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20 /* handle two cases, not four */
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21 if (sa == sb) {
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22 /* both positive or both negative */
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23 /* add their magnitudes, copy the sign */
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24 c->sign = sa;
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25 s_fp_add (a, b, c);
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26 } else {
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27 /* one positive, the other negative */
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28 /* subtract the one with the greater magnitude from */
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29 /* the one of the lesser magnitude. The result gets */
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30 /* the sign of the one with the greater magnitude. */
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31 if (fp_cmp_mag (a, b) == FP_LT) {
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32 c->sign = sb;
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33 s_fp_sub (b, a, c);
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34 } else {
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35 c->sign = sa;
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36 s_fp_sub (a, b, c);
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37 }
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38 }
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39 }
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40
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41 /* $Source$ */
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42 /* $Revision$ */
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43 /* $Date$ */