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bignum_number.c
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bignum_number.c
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void biggcd(int *x,int *y)
{
int *z;
while(1)
{
if(y[0]==1 && y[1]==0)return;
modbig(x,y);
z=y;y=x;x=z;
}
}
void MODULAR_EXPONENTIATION(int *a,int *b,int *n)
{
BG d,z;
int i;
d[0]=1;d[1]=1;
for(i=b[0];i>=1;i--)
{
mulbig(d,d,z);
modbig(z,n,d);
if(b[i]==1)
{
mulbig(d,a,z);
modbig(z,n,d);
}
}
cpybig(a,d);
}
void egcdbig(int *a,int *b,int *d,int *x,int *xf,int *y,int *yf)
{
static BG z[2000];
static BG t;
int f,now;
now=++C;
if(iszero(b)){cpybig(d,a);x[0]=x[1]=y[0]=1;y[1]=0;*xf=*yf=0;return;}
divmodbig(a,b,z[now]);
egcdbig(b,a,d,x,xf,y,yf);
mulbig(z[now],y,t);
cpybig(z[now],y);
f=*yf;
if(*xf==0 && *yf==0)
{
if(cmpbig(x,t)>=0)
subbig(x,t,y);
else
{
subbig(t,x,y);
*yf=1;
}
}
else if(*xf==0 && *yf==1)
{
addbig(x,t,y);
*yf=0;
}
else if(*xf==1 && *yf==0)
{
addbig(x,t,y);
*yf=1;
}
else if(*xf==1 && *yf==1)
{
if(cmpbig(x,t)>0)
subbig(x,t,y);
else
{
subbig(t,x,y);
*yf=0;
}
}
cpybig(x,z[now]);
*xf=f;
}