57 lines · 906 B · C
RawDownload
#include "os.h"#include <mp.h>#include "dat.h" // res = b >> shiftvoidmpright(mpint *b, int shift, mpint *res){	int d, l, r, i;	mpdigit this, last; 	res->sign = b->sign;	if(b->top==0){		res->top = 0;		return;	} 	// 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);	else if(shift == 0)		return; 	d = shift/Dbits;	r = shift - d*Dbits;	l = Dbits - r; 	//  shift all the bits out == zero	if(d>=b->top){		res->sign = 1;		res->top = 0;		return;	} 	// 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;	} 	res->top = i;	res->flags |= b->flags & MPtimesafe;	mpnorm(res);}