/* * ecvt.c - conversion routines for printing floating point numbers */ /* $Header$ */ #ifndef NOFLOAT static char *cvt(long double value, int ndigit, int *decpt, int *sign, int ecvtflag); #define NDIGITS 128 char * ecvt(long double value, int ndigit, int *decpt, int *sign) { return cvt(value, ndigit, decpt, sign, 1); } char * fcvt(long double value, int ndigit, int *decpt, int *sign) { return cvt(value, ndigit, decpt, sign, 0); } static struct powers_of_10 { long double pval; long double rpval; int exp; } p10[] = { 1.0e32, 1.0e-32, 32, 1.0e16, 1.0e-16, 16, 1.0e8, 1.0e-8, 8, 1.0e4, 1.0e-4, 4, 1.0e2, 1.0e-2, 2, 1.0e1, 1.0e-1, 1, 1.0e0, 1.0e0, 0 }; static char * cvt(long double value, int ndigit, int *decpt, int *sign, int ecvtflag) { static char buf[NDIGITS+1]; register char *p = buf; register char *pe; if (ndigit < 0) ndigit = 0; if (ndigit > NDIGITS) ndigit = NDIGITS; pe = &buf[ndigit]; buf[0] = '\0'; *sign = 0; if (value < 0) { *sign = 1; value = -value; } *decpt = 0; if (value != 0.0) { register struct powers_of_10 *pp = &p10[0]; if (value >= 10.0) do { while (value >= pp->pval) { value *= pp->rpval; *decpt += pp->exp; } } while ((++pp)->exp > 0); pp = &p10[0]; if (value < 1.0) do { while (value * pp->pval < 10.0) { value *= pp->pval; *decpt -= pp->exp; } } while ((++pp)->exp > 0); (*decpt)++; /* because now value in [1.0, 10.0) */ } if (!ecvtflag) { /* for fcvt() we need ndigit digits behind the dot */ pe += *decpt; if (pe > &buf[NDIGITS]) pe = &buf[NDIGITS]; } while (p <= pe) { *p++ = (int)value + '0'; value = 10.0 * (value - (int)value); } if (pe >= buf) { p = pe; *p += 5; /* round of at the end */ while (*p > '9') { *p = '0'; if (p > buf) ++*--p; else { *p = '1'; ++*decpt; if (!ecvtflag) { /* maybe add another digit at the end, because the point was shifted right */ if (pe > buf) *pe = '0'; pe++; } } } *pe = '\0'; } return buf; } #endif /* NOFLOAT */