ref: a69ae5ed2a33e8d1a62391e57347285228ba4054
dir: /3rd/mp/mpfmt.c/
#include "platform.h" static int topow2(mpint *b, char *buf, int len, int s) { mpdigit *p, x; int i, j, sn; char *out, *eout; if(len < 1) return -1; sn = 1<<s; out = buf; eout = buf+len; for(p = b->p+b->top-1; p >= b->p; p--){ x = *p; for(i = Dbits-s; i >= 0; i -= s){ j = x >> i & sn - 1; if(j != 0 || out != buf){ if(out >= eout) return -1; *out++ = enc16chr(j); } } } if(out == buf) *out++ = '0'; if(out >= eout) return -1; *out = 0; return 0; } static char* modbillion(int rem, uint32_t r, char *out, char *buf) { uint32_t rr; int i; for(i = 0; i < 9; i++){ rr = r%10; r /= 10; if(out <= buf) return nil; *--out = '0' + rr; if(rem == 0 && r == 0) break; } return out; } static int to10(mpint *b, char *buf, int len) { mpint *d, *r, *billion; char *out; if(len < 1) return -1; d = mpcopy(b); d->flags &= ~MPtimesafe; mpnorm(d); r = mpnew(0); billion = uitomp(1000000000, nil); out = buf+len; *--out = 0; do { mpdiv(d, billion, d, r); out = modbillion(d->top, r->p[0], out, buf); if(out == nil) break; } while(d->top != 0); mpfree(d); mpfree(r); mpfree(billion); if(out == nil) return -1; len -= out-buf; if(out != buf) memmove(buf, out, len); return 0; } static int to8(mpint *b, char *buf, int len) { mpdigit x, y; char *out; uint32_t j; int i; if(len < 2) return -1; out = buf+len; *--out = 0; i = j = 0; x = y = 0; while(j < b->top){ y = b->p[j++]; if(i > 0) x |= y << i; else x = y; i += Dbits; while(i >= 3){ Digout: i -= 3; if(out > buf) out--; else if(x != 0) return -1; *out = '0' + (x & 7); x = y >> (Dbits-i); } } if(i > 0) goto Digout; while(*out == '0') out++; if(*out == '\0') *--out = '0'; len -= out-buf; if(out != buf) memmove(buf, out, len); return 0; } char* mptoa(mpint *b, int base, char *buf, int len) { char *out; int rv, alloced; if(base == 0) base = 16; /* default */ alloced = 0; if(buf == nil){ /* rv <= log₂(base) */ for(rv=1; (base >> rv) > 1; rv++) ; len = 10 + (b->top*Dbits / rv); buf = MEM_ALLOC(len); if(buf == nil) return nil; alloced = 1; } if(len < 2) return nil; out = buf; if(b->sign < 0){ *out++ = '-'; len--; } switch(base){ case 16: rv = topow2(b, out, len, 4); break; case 10: rv = to10(b, out, len); break; case 8: rv = to8(b, out, len); break; case 4: rv = topow2(b, out, len, 2); break; case 2: rv = topow2(b, out, len, 1); break; default: fprintf(stderr, "mptoa: invalid base: %d\n", base); exit(2); } if(rv < 0){ if(alloced) MEM_FREE(buf); return nil; } return buf; }