Subversion Repositories planix.SVN

#include "os.h"
#include <mp.h>
#include "dat.h"

/*
        mplogic calculates b1|b2 subject to the
        following flag bits (fl)

        bit 0: subtract 1 from b1
        bit 1: invert b1
        bit 2: subtract 1 from b2
        bit 3: invert b2
        bit 4: add 1 to output
        bit 5: invert output
        
        it inverts appropriate bits automatically
        depending on the signs of the inputs
*/

static void
mplogic(mpint *b1, mpint *b2, mpint *sum, int fl)
{
        mpint *t;
        mpdigit *dp1, *dp2, *dpo, d1, d2, d;
        int c1, c2, co;
        int i;

        assert(((b1->flags | b2->flags | sum->flags) & MPtimesafe) == 0);
        if(b1->sign < 0) fl ^= 0x03;
        if(b2->sign < 0) fl ^= 0x0c;
        sum->sign = (int)(((fl|fl>>2)^fl>>4)<<30)>>31|1;
        if(sum->sign < 0) fl ^= 0x30;
        if(b2->top > b1->top){
                t = b1;
                b1 = b2;
                b2 = t;
                fl = fl >> 2 & 0x03 | fl << 2 & 0x0c | fl & 0x30;
        }
        mpbits(sum, b1->top*Dbits+1);
        dp1 = b1->p;
        dp2 = b2->p;
        dpo = sum->p;
        c1 = fl & 1;
        c2 = fl >> 2 & 1;
        co = fl >> 4 & 1;
        for(i = 0; i < b1->top; i++){
                d1 = dp1[i] - c1;
                if(i < b2->top)
                        d2 = dp2[i] - c2;
                else
                        d2 = 0;
                if(d1 != (mpdigit)-1) c1 = 0;
                if(d2 != (mpdigit)-1) c2 = 0;
                if((fl & 2) != 0) d1 ^= -1;
                if((fl & 8) != 0) d2 ^= -1;
                d = d1 | d2;
                if((fl & 32) != 0) d ^= -1;
                d += co;
                if(d != 0) co = 0;
                dpo[i] = d;
        }
        sum->top = i;
        if(co)
                dpo[sum->top++] = co;
        mpnorm(sum);
}

void
mpor(mpint *b1, mpint *b2, mpint *sum)
{
        mplogic(b1, b2, sum, 0);
}

void
mpand(mpint *b1, mpint *b2, mpint *sum)
{
        mplogic(b1, b2, sum, 0x2a);
}

void
mpbic(mpint *b1, mpint *b2, mpint *sum)
{
        mplogic(b1, b2, sum, 0x22);
}

void
mpnot(mpint *b, mpint *r)
{
        mpadd(b, mpone, r);
        if(r->top != 0)
                r->sign ^= -2;
}

void
mpxor(mpint *b1, mpint *b2, mpint *sum)
{
        mpint *t;
        mpdigit *dp1, *dp2, *dpo, d1, d2, d;
        int c1, c2, co;
        int i, fl;

        assert(((b1->flags | b2->flags | sum->flags) & MPtimesafe) == 0);
        if(b2->top > b1->top){
                t = b1;
                b1 = b2;
                b2 = t;
        }
        fl = (b1->sign & 10) ^ (b2->sign & 12);
        sum->sign = (int)(fl << 28) >> 31 | 1;
        mpbits(sum, b1->top*Dbits+1);
        dp1 = b1->p;
        dp2 = b2->p;
        dpo = sum->p;
        c1 = fl >> 1 & 1;
        c2 = fl >> 2 & 1;
        co = fl >> 3 & 1;
        for(i = 0; i < b1->top; i++){
                d1 = dp1[i] - c1;
                if(i < b2->top)
                        d2 = dp2[i] - c2;
                else
                        d2 = 0;
                if(d1 != (mpdigit)-1) c1 = 0;
                if(d2 != (mpdigit)-1) c2 = 0;
                d = d1 ^ d2;
                d += co;
                if(d != 0) co = 0;
                dpo[i] = d;
        }
        sum->top = i;
        if(co)
                dpo[sum->top++] = co;
        mpnorm(sum);
}

void
mptrunc(mpint *b, int n, mpint *r)
{
        int d, m, i, c;

        assert(((b->flags | r->flags) & MPtimesafe) == 0);
        mpbits(r, n);
        r->top = DIGITS(n);
        d = n / Dbits;
        m = n % Dbits;
        if(b->sign == -1){
                c = 1;
                for(i = 0; i < r->top; i++){
                        if(i < b->top)
                                r->p[i] = ~(b->p[i] - c);
                        else
                                r->p[i] = -1;
                        if(r->p[i] != 0)
                                c = 0;
                }
                if(m != 0)
                        r->p[d] &= (1<<m) - 1;
        }else if(b->sign == 1){
                if(d >= b->top){
                        mpassign(b, r);
                        mpnorm(r);
                        return;
                }
                if(b != r)
                        for(i = 0; i < d; i++)
                                r->p[i] = b->p[i];
                if(m != 0)
                        r->p[d] = b->p[d] & (1<<m)-1;
        }
        r->sign = 1;
        mpnorm(r);
}

void
mpxtend(mpint *b, int n, mpint *r)
{
        int d, m, c, i;

        d = (n - 1) / Dbits;
        m = (n - 1) % Dbits;
        if(d >= b->top){
                mpassign(b, r);
                return;
        }
        mptrunc(b, n, r);
        mpbits(r, n);
        if((r->p[d] & 1<<m) == 0){
                mpnorm(r);
                return;
        }
        r->p[d] |= -(1<<m);
        r->sign = -1;
        c = 1;
        for(i = 0; i < r->top; i++){
                r->p[i] = ~(r->p[i] - c);
                if(r->p[i] != 0)
                        c = 0;
        }
        mpnorm(r);
}

void
mpasr(mpint *b, int n, mpint *r)
{
        if(b->sign > 0 || n <= 0){
                mpright(b, n, r);
                return;
        }
        mpadd(b, mpone, r);
        mpright(r, n, r);
        mpsub(r, mpone, r);
}