ref: caef73363f896a1405ce6b9b6435f91e47a9b188
dir: /libmp/port/mpright.c/
#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; 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); d = shift/Dbits; r = shift - d*Dbits; l = Dbits - r; // shift all the bits out == zero if(d>=b->top){ 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; } while(i > 0 && res->p[i-1] == 0) i--; res->top = i; if(i==0) res->sign = 1; }