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#include "os.h"
#include <mp.h>
#include "dat.h"
// res = b >> shift
void
mpright(mpint *b, int shift, mpint *res)
{
int d, l, r, i;
mpdigit this, last;
// a negative right shift is a left shift
if(shift < 0){
mpleft(b, -shift, res);
return;
}
if(res != b)
mpbits(res, b->top*Dbits - shift);
d = shift/Dbits;
r = shift - d*Dbits;
l = Dbits - r;
// special case digit shifts
if(r == 0){
for(i = 0; i < b->top-d; i++)
res->p[i] = b->p[i+d];
} else {
last = b->p[d];
for(i = 0; i < b->top-d-1; i++){
this = b->p[i+d+1];
res->p[i] = (this<<l) | (last>>r);
last = this;
}
res->p[i++] = last>>r;
}
while(i > 0 && res->p[i-1] == 0)
i--;
res->top = i;
}
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