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added multiplication

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Veit Heller
2017-07-29 17:11:24 -04:00
parent 76fcdbeb16
commit 428360db07
4 changed files with 50 additions and 3 deletions
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23
silly.c
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@@ -24,7 +24,7 @@ silly silly_add(silly x, silly y) {
z.before = x.before + y.before;
z.after = x.after + y.after;
if (z.after < x.after && z.after < y.after) z.before += 1;
if (z.after < x.after && z.after < y.after) z.before++;
return z;
}
@@ -53,7 +53,26 @@ silly silly_sub(silly x, silly y) {
z.after = x.after - y.after;
if (z.after > x.after) z.before -= 1;
if (z.after > x.after) z.before--;
return z;
}
silly silly_mul(silly x, silly y) {
silly z = silly_zeros();
z.sign = x.sign ^ y.sign;
uint64_t t0 = (x.before * y.after);
uint64_t t1 = (y.before * x.after);
z.before = x.before * y.before + (t0>>32) + (t1>>32);
uint32_t t0b = t0&0xffffffff;
uint32_t t1b = t1&0xffffffff;
uint32_t tsum = t0b + t1b;
if (tsum < t0b || tsum < t1b) z.before++;
z.after = x.after * y.after + tsum;
if (z.after < tsum) z.before++;
return z;
}