43 lines
714 B
C
43 lines
714 B
C
#include "os.h"
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#include <mp.h>
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#include "dat.h"
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// res = s != 0 ? b1 : b2
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void
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mpsel(int s, mpint *b1, mpint *b2, mpint *res)
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{
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mpdigit d;
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int n, m, i;
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res->flags |= (b1->flags | b2->flags) & MPtimesafe;
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if((res->flags & MPtimesafe) == 0){
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mpassign(s ? b1 : b2, res);
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return;
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}
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res->flags &= ~MPnorm;
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n = b1->top;
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m = b2->top;
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mpbits(res, Dbits*(n >= m ? n : m));
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res->top = n >= m ? n : m;
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s = (-s^s|s)>>(sizeof(s)*8-1);
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res->sign = (b1->sign & s) | (b2->sign & ~s);
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d = -((mpdigit)s & 1);
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i = 0;
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while(i < n && i < m){
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res->p[i] = (b1->p[i] & d) | (b2->p[i] & ~d);
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i++;
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}
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while(i < n){
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res->p[i] = b1->p[i] & d;
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i++;
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}
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while(i < m){
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res->p[i] = b2->p[i] & ~d;
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i++;
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}
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}
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