ref: e19308ee166dd085f7773621471a5fc589af45d4
dir: /sys/src/libmp/port/strtomp.c/
#include "os.h" #include <mp.h> #include "dat.h" static struct { int inited; uchar t64[256]; uchar t32[256]; uchar t16[256]; uchar t10[256]; } tab; enum { INVAL= 255 }; static char set64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; static char set32[] = "23456789abcdefghijkmnpqrstuvwxyz"; static char set16[] = "0123456789ABCDEF0123456789abcdef"; static char set10[] = "0123456789"; static void init(void) { char *p; memset(tab.t64, INVAL, sizeof(tab.t64)); memset(tab.t32, INVAL, sizeof(tab.t32)); memset(tab.t16, INVAL, sizeof(tab.t16)); memset(tab.t10, INVAL, sizeof(tab.t10)); for(p = set64; *p; p++) tab.t64[*p] = p-set64; for(p = set32; *p; p++) tab.t32[*p] = p-set32; for(p = set16; *p; p++) tab.t16[*p] = (p-set16)%16; for(p = set10; *p; p++) tab.t10[*p] = (p-set10); tab.inited = 1; } static char* frompow2(char *a, mpint *b, int s) { char *p, *next; int i; mpdigit x; int sn; sn = 1<<s; for(p = a; *p; p++) if(tab.t16[*(uchar*)p] >= sn) break; mpbits(b, (p-a)*s); b->top = 0; next = p; while(p > a){ x = 0; for(i = 0; i < Dbits; i += s){ if(p <= a) break; x |= tab.t16[*(uchar*)--p]<<i; } b->p[b->top++] = x; } return next; } static char* from8(char *a, mpint *b) { char *p, *next; mpdigit x, y; int i; for(p = a; *p; p++) if(tab.t10[*(uchar*)p] >= 8) break; mpbits(b, (p-a)*3); b->top = 0; next = p; i = 0; x = y = 0; while(p > a){ y = tab.t10[*(uchar*)--p]; x |= y << i; i += 3; if(i >= Dbits){ Digout: i -= Dbits; b->p[b->top++] = x; x = y >> 3-i; } } if(i > 0) goto Digout; return next; } static ulong mppow10[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 }; static char* from10(char *a, mpint *b) { ulong x, y; mpint *pow, *r; int i; pow = mpnew(0); r = mpnew(0); b->top = 0; for(;;){ // do a billion at a time in native arithmetic x = 0; for(i = 0; i < 9; i++){ y = tab.t10[*(uchar*)a]; if(y == INVAL) break; a++; x *= 10; x += y; } if(i == 0) break; // accumulate into mpint uitomp(mppow10[i], pow); uitomp(x, r); mpmul(b, pow, b); mpadd(b, r, b); if(i != 9) break; } mpfree(pow); mpfree(r); return a; } static char* fromdecx(char *a, mpint *b, uchar tab[256], int (*dec)(uchar*, int, char*, int)) { char *buf = a; uchar *p; int n, m; b->top = 0; for(; tab[*(uchar*)a] != INVAL; a++) ; n = a-buf; if(n > 0){ p = malloc(n); if(p == nil) sysfatal("malloc: %r"); m = (*dec)(p, n, buf, n); if(m > 0) betomp(p, m, b); free(p); } return a; } mpint* strtomp(char *a, char **pp, int base, mpint *b) { int sign; char *e; if(b == nil){ b = mpnew(0); setmalloctag(b, getcallerpc(&a)); } if(tab.inited == 0) init(); while(*a==' ' || *a=='\t') a++; sign = 1; for(;; a++){ switch(*a){ case '-': sign *= -1; continue; } break; } if(base == 0){ base = 10; if(a[0] == '0'){ if(a[1] == 'x' || a[1] == 'X') { a += 2; base = 16; } else if(a[1] == 'b' || a[1] == 'B') { a += 2; base = 2; } else if(a[1] >= '0' && a[1] <= '7') { a++; base = 8; } } } switch(base){ case 2: e = frompow2(a, b, 1); break; case 4: e = frompow2(a, b, 2); break; case 8: e = from8(a, b); break; case 10: e = from10(a, b); break; case 16: e = frompow2(a, b, 4); break; case 32: e = fromdecx(a, b, tab.t32, dec32); break; case 64: e = fromdecx(a, b, tab.t64, dec64); break; default: abort(); return nil; } if(pp != nil) *pp = e; // if no characters parsed, there wasn't a number to convert if(e == a) return nil; b->sign = sign; return mpnorm(b); }