ref: 1018d7a7091fd5e0433f501a3474cdc3fec322cc
dir: /libmp/port/mptobe.c/
#include "os.h" #include <mp.h> #include "dat.h" // convert an mpint into a big endian byte array (most significant byte first) // return number of bytes converted // if p == nil, allocate and result array int mptobe(mpint *b, uchar *p, uint n, uchar **pp) { int i, j, suppress; mpdigit x; uchar *e, *s, c; if(p == nil){ n = (b->top+1)*Dbytes; p = malloc(n); } if(p == nil) return -1; if(pp != nil) *pp = p; memset(p, 0, n); // special case 0 if(b->top == 0){ if(n < 1) return -1; else return 1; } s = p; e = s+n; suppress = 1; for(i = b->top-1; i >= 0; i--){ x = b->p[i]; for(j = Dbits-8; j >= 0; j -= 8){ c = x>>j; if(c == 0 && suppress) continue; if(p >= e) return -1; *p++ = c; suppress = 0; } } // guarantee at least one byte if(s == p){ if(p >= e) return -1; *p++ = 0; } return p - s; }