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