ref: b502a62da2ec6058923db94f87ecc2d29db2fa77
dir: /libmp/port/mptov.c/
#include "os.h" #include <mp.h> #include "dat.h" #define VLDIGITS (sizeof(vlong)/sizeof(mpdigit)) /* * this code assumes that a vlong is an integral number of * mpdigits long. */ mpint* vtomp(vlong v, mpint *b) { int s; uvlong uv; if(b == nil) b = mpnew(VLDIGITS*sizeof(mpdigit)); else mpbits(b, VLDIGITS*sizeof(mpdigit)); mpassign(mpzero, b); if(v == 0) return b; if(v < 0){ b->sign = -1; uv = -v; } else uv = v; for(s = 0; s < VLDIGITS && uv != 0; s++){ b->p[s] = uv; uv >>= sizeof(mpdigit)*8; } b->top = s; return b; } vlong mptov(mpint *b) { uvlong v; int s; if(b->top == 0) return 0; mpnorm(b); if(b->top > VLDIGITS){ if(b->sign > 0) return (vlong)MAXVLONG; else return (vlong)MINVLONG; } v = 0; for(s = 0; s < b->top; s++) v |= b->p[s]<<(s*sizeof(mpdigit)*8); if(b->sign > 0){ if(v > MAXVLONG) v = MAXVLONG; } else { if(v > MINVLONG) v = MINVLONG; else v = -(vlong)v; } return (vlong)v; }