ref: 94814a2e3472dbfdecc179f6c24658591fd168a6
dir: /llt/dblprint.c/
#include <math.h> #include <stdlib.h> #include <string.h> #include <stdio.h> #include "ieee754.h" #include "dtypes.h" int double_exponent(double d) { union ieee754_double dl; dl.d = d; return dl.ieee.exponent - IEEE754_DOUBLE_BIAS; } double double_mantissa(double d) { union ieee754_double dl; dl.d = d; dl.ieee.exponent = IEEE754_DOUBLE_BIAS; dl.ieee.negative = 0; return dl.d; } int float_exponent(float f) { union ieee754_float fl; fl.f = f; return fl.ieee.exponent - IEEE754_FLOAT_BIAS; } float float_mantissa(float f) { union ieee754_float fl; fl.f = f; fl.ieee.exponent = IEEE754_FLOAT_BIAS; fl.ieee.negative = 0; return fl.f; } void snprint_real(char *s, size_t cnt, double r, int width, // printf field width, or 0 int dec, // # decimal digits desired, recommend 16 // # of zeros in .00...0x before using scientific notation // recommend 3-4 or so int max_digs_rt, // # of digits left of decimal before scientific notation // recommend 10 int max_digs_lf) { int mag; double fpart, temp; char format[8]; char num_format[3]; int sz, keepz=0; s[0] = '\0'; if (width == -1) { width = 0; keepz=1; } if (isnan(r)) { if (sign_bit(r)) strncpy(s, "-nan", cnt); else strncpy(s, "nan", cnt); return; } if (r == 0) { strncpy(s, "0", cnt); return; } num_format[0] = 'l'; num_format[2] = '\0'; mag = double_exponent(r); mag = (int)(((double)mag)/LOG2_10 + 0.5); if (r == 0) mag = 0; if ((mag > max_digs_lf-1) || (mag < -max_digs_rt)) { num_format[1] = 'e'; temp = r/pow(10, mag); /* see if number will have a decimal */ fpart = temp - floor(temp); /* when written in scientific notation */ } else { num_format[1] = 'f'; fpart = r - floor(r); } if (fpart == 0) dec = 0; if (width == 0) { snprintf(format, 8, "%%.%d%s", dec, num_format); } else { snprintf(format, 8, "%%%d.%d%s", width, dec, num_format); } sz = snprintf(s, cnt, format, r); /* trim trailing zeros from fractions. not when using scientific notation, since we might have e.g. 1.2000e+100. also not when we need a specific output width */ if (width == 0 && !keepz) { if (sz > 2 && fpart && num_format[1]!='e') { while (s[sz-1] == '0') { s[sz-1]='\0'; sz--; } // don't need trailing . if (s[sz-1] == '.') { s[sz-1] = '\0'; sz--; } } } // TODO. currently 1.1e20 prints as 1.1000000000000000e+20; be able to // get rid of all those zeros. }