1*8ccd4a63SDavid du Colombier #include "os.h"
2*8ccd4a63SDavid du Colombier #include <mp.h>
3*8ccd4a63SDavid du Colombier #include "dat.h"
4*8ccd4a63SDavid du Colombier
5*8ccd4a63SDavid du Colombier // res = b >> shift
6*8ccd4a63SDavid du Colombier void
mpright(mpint * b,int shift,mpint * res)7*8ccd4a63SDavid du Colombier mpright(mpint *b, int shift, mpint *res)
8*8ccd4a63SDavid du Colombier {
9*8ccd4a63SDavid du Colombier int d, l, r, i;
10*8ccd4a63SDavid du Colombier mpdigit this, last;
11*8ccd4a63SDavid du Colombier
12*8ccd4a63SDavid du Colombier // a negative right shift is a left shift
13*8ccd4a63SDavid du Colombier if(shift < 0){
14*8ccd4a63SDavid du Colombier mpleft(b, -shift, res);
15*8ccd4a63SDavid du Colombier return;
16*8ccd4a63SDavid du Colombier }
17*8ccd4a63SDavid du Colombier
18*8ccd4a63SDavid du Colombier if(res != b)
19*8ccd4a63SDavid du Colombier mpbits(res, b->top*Dbits - shift);
20*8ccd4a63SDavid du Colombier d = shift/Dbits;
21*8ccd4a63SDavid du Colombier r = shift - d*Dbits;
22*8ccd4a63SDavid du Colombier l = Dbits - r;
23*8ccd4a63SDavid du Colombier
24*8ccd4a63SDavid du Colombier // special case digit shifts
25*8ccd4a63SDavid du Colombier if(r == 0){
26*8ccd4a63SDavid du Colombier for(i = 0; i < b->top-d; i++)
27*8ccd4a63SDavid du Colombier res->p[i] = b->p[i+d];
28*8ccd4a63SDavid du Colombier } else {
29*8ccd4a63SDavid du Colombier last = b->p[d];
30*8ccd4a63SDavid du Colombier for(i = 0; i < b->top-d-1; i++){
31*8ccd4a63SDavid du Colombier this = b->p[i+d+1];
32*8ccd4a63SDavid du Colombier res->p[i] = (this<<l) | (last>>r);
33*8ccd4a63SDavid du Colombier last = this;
34*8ccd4a63SDavid du Colombier }
35*8ccd4a63SDavid du Colombier res->p[i++] = last>>r;
36*8ccd4a63SDavid du Colombier }
37*8ccd4a63SDavid du Colombier while(i > 0 && res->p[i-1] == 0)
38*8ccd4a63SDavid du Colombier i--;
39*8ccd4a63SDavid du Colombier res->top = i;
40*8ccd4a63SDavid du Colombier }
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