195 lines
3.2 KiB
C
195 lines
3.2 KiB
C
#include "os.h"
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#include <mp.h>
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#include "dat.h"
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/*
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mplogic calculates b1|b2 subject to the
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following flag bits (fl)
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bit 0: subtract 1 from b1
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bit 1: invert b1
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bit 2: subtract 1 from b2
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bit 3: invert b2
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bit 4: add 1 to output
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bit 5: invert output
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it inverts appropriate bits automatically
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depending on the signs of the inputs
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*/
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static void
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mplogic(mpint *b1, mpint *b2, mpint *sum, int fl)
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{
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mpint *t;
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mpdigit *dp1, *dp2, *dpo, d1, d2, d;
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int c1, c2, co;
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int i;
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assert(((b1->flags | b2->flags | sum->flags) & MPtimesafe) == 0);
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if(b1->sign < 0) fl ^= 0x03;
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if(b2->sign < 0) fl ^= 0x0c;
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sum->sign = (int)(((fl|fl>>2)^fl>>4)<<30)>>31|1;
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if(sum->sign < 0) fl ^= 0x30;
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if(b2->top > b1->top){
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t = b1;
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b1 = b2;
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b2 = t;
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fl = fl >> 2 & 0x03 | fl << 2 & 0x0c | fl & 0x30;
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}
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mpbits(sum, b1->top*Dbits);
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dp1 = b1->p;
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dp2 = b2->p;
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dpo = sum->p;
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c1 = fl & 1;
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c2 = fl >> 2 & 1;
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co = fl >> 4 & 1;
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for(i = 0; i < b1->top; i++){
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d1 = dp1[i] - c1;
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if(i < b2->top)
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d2 = dp2[i] - c2;
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else
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d2 = 0;
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if(d1 != (mpdigit)-1) c1 = 0;
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if(d2 != (mpdigit)-1) c2 = 0;
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if((fl & 2) != 0) d1 ^= -1;
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if((fl & 8) != 0) d2 ^= -1;
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d = d1 | d2;
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if((fl & 32) != 0) d ^= -1;
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d += co;
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if(d != 0) co = 0;
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dpo[i] = d;
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}
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sum->top = i;
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mpnorm(sum);
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}
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void
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mpor(mpint *b1, mpint *b2, mpint *sum)
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{
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mplogic(b1, b2, sum, 0);
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}
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void
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mpand(mpint *b1, mpint *b2, mpint *sum)
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{
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mplogic(b1, b2, sum, 0x2a);
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}
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void
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mpbic(mpint *b1, mpint *b2, mpint *sum)
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{
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mplogic(b1, b2, sum, 0x22);
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}
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void
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mpnot(mpint *b, mpint *r)
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{
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mpadd(b, mpone, r);
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r->sign ^= -2;
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}
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void
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mpxor(mpint *b1, mpint *b2, mpint *sum)
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{
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mpint *t;
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mpdigit *dp1, *dp2, *dpo, d1, d2, d;
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int c1, c2, co;
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int i, fl;
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assert(((b1->flags | b2->flags | sum->flags) & MPtimesafe) == 0);
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if(b2->top > b1->top){
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t = b1;
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b1 = b2;
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b2 = t;
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}
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fl = (b1->sign & 10) ^ (b2->sign & 12);
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sum->sign = (int)(fl << 28) >> 31;
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mpbits(sum, b1->top*Dbits);
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dp1 = b1->p;
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dp2 = b2->p;
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dpo = sum->p;
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c1 = fl >> 1 & 1;
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c2 = fl >> 2 & 1;
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co = fl >> 3 & 1;
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for(i = 0; i < b1->top; i++){
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d1 = dp1[i] - c1;
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if(i < b2->top)
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d2 = dp2[i] - c2;
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else
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d2 = 0;
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if(d1 != (mpdigit)-1) c1 = 0;
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if(d2 != (mpdigit)-1) c2 = 0;
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d = d1 ^ d2;
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d += co;
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if(d != 0) co = 0;
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dpo[i] = d;
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}
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sum->top = i;
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mpnorm(sum);
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}
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void
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mptrunc(mpint *b, int n, mpint *r)
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{
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int d, m, i, c;
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assert(((b->flags | r->flags) & MPtimesafe) == 0);
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mpbits(r, n);
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r->top = DIGITS(n);
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d = n / Dbits;
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m = n % Dbits;
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if(b->sign == -1){
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c = 1;
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for(i = 0; i <= r->top; i++){
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if(i < b->top)
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r->p[i] = ~(b->p[i] - c);
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else
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r->p[i] = -1;
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if(r->p[i] != 0)
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c = 0;
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}
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if(m != 0)
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r->p[d] &= (1<<m) - 1;
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}else if(b->sign == 1){
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if(d >= b->top){
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mpassign(b, r);
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return;
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}
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if(b != r)
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for(i = 0; i < d; i++)
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r->p[i] = b->p[i];
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if(m != 0)
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r->p[d] = b->p[d] & (1<<m)-1;
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}
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r->sign = 1;
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mpnorm(r);
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}
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void
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mpxtend(mpint *b, int n, mpint *r)
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{
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int d, m, c, i;
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d = (n - 1) / Dbits;
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m = (n - 1) % Dbits;
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if(d >= b->top){
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mpassign(b, r);
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return;
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}
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mptrunc(b, n, r);
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mpbits(r, n);
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if((r->p[d] & 1<<m) == 0){
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mpnorm(r);
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return;
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}
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r->p[d] |= -(1<<m);
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r->sign = -1;
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c = 1;
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for(i = 0; i < r->top; i++){
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r->p[i] = ~(r->p[i] - c);
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if(r->p[i] != 0)
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c = 0;
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}
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mpnorm(r);
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}
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