452 lines
8.5 KiB
C
452 lines
8.5 KiB
C
/*
|
|
FUNCTION
|
|
<<ecvtbuf>>, <<fcvtbuf>>---double or float to string
|
|
|
|
INDEX
|
|
ecvtbuf
|
|
INDEX
|
|
fcvtbuf
|
|
|
|
SYNOPSIS
|
|
#include <stdio.h>
|
|
|
|
char *ecvtbuf(double <[val]>, int <[chars]>, int *<[decpt]>,
|
|
int *<[sgn]>, char *<[buf]>);
|
|
|
|
char *fcvtbuf(double <[val]>, int <[decimals]>, int *<[decpt]>,
|
|
int *<[sgn]>, char *<[buf]>);
|
|
|
|
DESCRIPTION
|
|
<<ecvtbuf>> and <<fcvtbuf>> produce (null-terminated) strings
|
|
of digits representating the <<double>> number <[val]>.
|
|
|
|
The only difference between <<ecvtbuf>> and <<fcvtbuf>> is the
|
|
interpretation of the second argument (<[chars]> or
|
|
<[decimals]>). For <<ecvtbuf>>, the second argument <[chars]>
|
|
specifies the total number of characters to write (which is
|
|
also the number of significant digits in the formatted string,
|
|
since these two functions write only digits). For <<fcvtbuf>>,
|
|
the second argument <[decimals]> specifies the number of
|
|
characters to write after the decimal point; all digits for
|
|
the integer part of <[val]> are always included.
|
|
|
|
Since <<ecvtbuf>> and <<fcvtbuf>> write only digits in the
|
|
output string, they record the location of the decimal point
|
|
in <<*<[decpt]>>>, and the sign of the number in <<*<[sgn]>>>.
|
|
After formatting a number, <<*<[decpt]>>> contains the number
|
|
of digits to the left of the decimal point. <<*<[sgn]>>>
|
|
contains <<0>> if the number is positive, and <<1>> if it is
|
|
negative. For both functions, you supply a pointer <[buf]> to
|
|
an area of memory to hold the converted string.
|
|
|
|
RETURNS
|
|
Both functions return a pointer to <[buf]>, the string
|
|
containing a character representation of <[val]>.
|
|
|
|
PORTABILITY
|
|
Neither function is ANSI C.
|
|
|
|
Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
|
|
<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
|
|
*/
|
|
|
|
#include <_ansi.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <reent.h>
|
|
#include "mprec.h"
|
|
#include "local.h"
|
|
|
|
#ifdef _REENT_THREAD_LOCAL
|
|
_Thread_local char *_tls_cvtbuf;
|
|
_Thread_local int _tls_cvtlen;
|
|
#endif
|
|
|
|
static void
|
|
print_f (struct _reent *ptr,
|
|
char *buf,
|
|
double invalue,
|
|
int ndigit,
|
|
char type,
|
|
int dot,
|
|
int mode)
|
|
{
|
|
int decpt;
|
|
int sign;
|
|
char *p, *start, *end;
|
|
|
|
start = p = _dtoa_r (ptr, invalue, mode, ndigit, &decpt, &sign, &end);
|
|
|
|
if (decpt == 9999)
|
|
{
|
|
strcpy (buf, p);
|
|
return;
|
|
}
|
|
while (*p && decpt > 0)
|
|
{
|
|
*buf++ = *p++;
|
|
decpt--;
|
|
}
|
|
/* Even if not in buffer */
|
|
while (decpt > 0)
|
|
{
|
|
*buf++ = '0';
|
|
decpt--;
|
|
}
|
|
|
|
if (dot || *p)
|
|
{
|
|
if (p == start)
|
|
*buf++ = '0';
|
|
if (decpt < 0 && ndigit > 0)
|
|
*buf++ = '.';
|
|
while (decpt < 0 && ndigit > 0)
|
|
{
|
|
*buf++ = '0';
|
|
decpt++;
|
|
ndigit--;
|
|
}
|
|
|
|
/* Print rest of stuff */
|
|
while (*p && ndigit > 0)
|
|
{
|
|
*buf++ = *p++;
|
|
ndigit--;
|
|
}
|
|
/* And trailing zeros */
|
|
while (ndigit > 0)
|
|
{
|
|
*buf++ = '0';
|
|
ndigit--;
|
|
}
|
|
}
|
|
*buf++ = 0;
|
|
}
|
|
|
|
/* Print number in e format with width chars after.
|
|
|
|
TYPE is one of 'e' or 'E'. It may also be one of 'g' or 'G' indicating
|
|
that _gcvt is calling us and we should remove trailing zeroes.
|
|
|
|
WIDTH is the number of digits of precision after the decimal point. */
|
|
|
|
static void
|
|
print_e (struct _reent *ptr,
|
|
char *buf,
|
|
double invalue,
|
|
int width,
|
|
char type,
|
|
int dot)
|
|
{
|
|
int sign;
|
|
char *end;
|
|
char *p;
|
|
int decpt;
|
|
int top;
|
|
int ndigit = width;
|
|
|
|
p = _dtoa_r (ptr, invalue, 2, width + 1, &decpt, &sign, &end);
|
|
|
|
if (decpt == 9999)
|
|
{
|
|
strcpy (buf, p);
|
|
return;
|
|
}
|
|
|
|
*buf++ = *p++;
|
|
if (ndigit > 0)
|
|
dot = 1;
|
|
|
|
while (*p && ndigit > 0)
|
|
{
|
|
if (dot) {
|
|
*buf++ = '.';
|
|
dot = 0;
|
|
}
|
|
*buf++ = *p++;
|
|
ndigit--;
|
|
}
|
|
|
|
/* Add trailing zeroes to fill out to ndigits unless this is 'g' format.
|
|
Also, convert g/G to e/E. */
|
|
|
|
if (type == 'g')
|
|
type = 'e';
|
|
else if (type == 'G')
|
|
type = 'E';
|
|
else
|
|
{
|
|
while (ndigit > 0)
|
|
{
|
|
if (dot) {
|
|
*buf++ = '.';
|
|
dot = 0;
|
|
}
|
|
*buf++ = '0';
|
|
ndigit--;
|
|
}
|
|
}
|
|
|
|
/* Add the exponent. */
|
|
|
|
*buf++ = type;
|
|
decpt--;
|
|
if (decpt < 0)
|
|
{
|
|
*buf++ = '-';
|
|
decpt = -decpt;
|
|
}
|
|
else
|
|
{
|
|
*buf++ = '+';
|
|
}
|
|
if (decpt > 99)
|
|
{
|
|
int top = decpt / 100;
|
|
*buf++ = top + '0';
|
|
decpt -= top * 100;
|
|
}
|
|
top = decpt / 10;
|
|
*buf++ = top + '0';
|
|
decpt -= top * 10;
|
|
*buf++ = decpt + '0';
|
|
|
|
*buf++ = 0;
|
|
}
|
|
|
|
#ifndef _REENT_ONLY
|
|
|
|
/* Undocumented behaviour: when given NULL as a buffer, return a
|
|
pointer to static space in the rent structure. This is only to
|
|
support ecvt and fcvt, which aren't ANSI anyway. */
|
|
|
|
char *
|
|
fcvtbuf (double invalue,
|
|
int ndigit,
|
|
int *decpt,
|
|
int *sign,
|
|
char *fcvt_buf)
|
|
{
|
|
struct _reent *reent = _REENT;
|
|
char *save;
|
|
char *p;
|
|
char *end;
|
|
int done = 0;
|
|
|
|
if (fcvt_buf == NULL)
|
|
{
|
|
if (_REENT_CVTLEN(reent) <= ndigit + 35)
|
|
{
|
|
if ((fcvt_buf = (char *) _realloc_r (reent, _REENT_CVTBUF(reent),
|
|
ndigit + 36)) == NULL)
|
|
return NULL;
|
|
_REENT_CVTLEN(reent) = ndigit + 36;
|
|
_REENT_CVTBUF(reent) = fcvt_buf;
|
|
}
|
|
|
|
fcvt_buf = _REENT_CVTBUF(reent) ;
|
|
}
|
|
|
|
save = fcvt_buf;
|
|
|
|
p = _dtoa_r (reent, invalue, 3, ndigit, decpt, sign, &end);
|
|
|
|
/* Now copy */
|
|
|
|
done = -*decpt;
|
|
while (p < end)
|
|
{
|
|
*fcvt_buf++ = *p++;
|
|
done++;
|
|
}
|
|
/* And unsuppress the trailing zeroes */
|
|
while (done < ndigit)
|
|
{
|
|
*fcvt_buf++ = '0';
|
|
done++;
|
|
}
|
|
*fcvt_buf++ = 0;
|
|
return save;
|
|
}
|
|
|
|
char *
|
|
ecvtbuf (double invalue,
|
|
int ndigit,
|
|
int *decpt,
|
|
int *sign,
|
|
char *fcvt_buf)
|
|
{
|
|
struct _reent *reent = _REENT;
|
|
char *save;
|
|
char *p;
|
|
char *end;
|
|
int done = 0;
|
|
|
|
if (fcvt_buf == NULL)
|
|
{
|
|
if (_REENT_CVTLEN(reent) <= ndigit)
|
|
{
|
|
if ((fcvt_buf = (char *) _realloc_r (reent, _REENT_CVTBUF(reent),
|
|
ndigit + 1)) == NULL)
|
|
return NULL;
|
|
_REENT_CVTLEN(reent) = ndigit + 1;
|
|
_REENT_CVTBUF(reent) = fcvt_buf;
|
|
}
|
|
|
|
fcvt_buf = _REENT_CVTBUF(reent) ;
|
|
}
|
|
|
|
save = fcvt_buf;
|
|
|
|
p = _dtoa_r (reent, invalue, 2, ndigit, decpt, sign, &end);
|
|
|
|
/* Now copy */
|
|
|
|
while (p < end)
|
|
{
|
|
*fcvt_buf++ = *p++;
|
|
done++;
|
|
}
|
|
/* And unsuppress the trailing zeroes */
|
|
while (done < ndigit)
|
|
{
|
|
*fcvt_buf++ = '0';
|
|
done++;
|
|
}
|
|
*fcvt_buf++ = 0;
|
|
return save;
|
|
}
|
|
|
|
#endif
|
|
|
|
char *
|
|
_gcvt (struct _reent *ptr,
|
|
double invalue,
|
|
int ndigit,
|
|
char *buf,
|
|
char type,
|
|
int dot)
|
|
{
|
|
char *save = buf;
|
|
|
|
if (invalue < 0)
|
|
{
|
|
invalue = -invalue;
|
|
}
|
|
|
|
if (invalue == 0)
|
|
{
|
|
*buf++ = '0';
|
|
*buf = '\0';
|
|
}
|
|
else
|
|
/* Which one to print ?
|
|
ANSI says that anything with more that 4 zeros after the . or more
|
|
than precision digits before is printed in e with the qualification
|
|
that trailing zeroes are removed from the fraction portion. */
|
|
|
|
if (0.0001 >= invalue || invalue >= _mprec_log10 (ndigit))
|
|
{
|
|
/* We subtract 1 from ndigit because in the 'e' format the precision is
|
|
the number of digits after the . but in 'g' format it is the number
|
|
of significant digits.
|
|
|
|
We defer changing type to e/E so that print_e() can know it's us
|
|
calling and thus should remove trailing zeroes. */
|
|
|
|
print_e (ptr, buf, invalue, ndigit - 1, type, dot);
|
|
}
|
|
else
|
|
{
|
|
int decpt;
|
|
int sign;
|
|
char *end;
|
|
char *p;
|
|
|
|
/* We always want ndigits of precision, even if that means printing
|
|
* a bunch of leading zeros for numbers < 1.0
|
|
*/
|
|
p = _dtoa_r (ptr, invalue, 2, ndigit, &decpt, &sign, &end);
|
|
|
|
if (decpt == 9999)
|
|
{
|
|
strcpy (buf, p);
|
|
return save;
|
|
}
|
|
while (*p && decpt > 0)
|
|
{
|
|
*buf++ = *p++;
|
|
decpt--;
|
|
ndigit--;
|
|
}
|
|
/* Even if not in buffer */
|
|
while (decpt > 0 && ndigit > 0)
|
|
{
|
|
*buf++ = '0';
|
|
decpt--;
|
|
ndigit--;
|
|
}
|
|
|
|
if (dot || *p)
|
|
{
|
|
if (buf == save)
|
|
*buf++ = '0';
|
|
*buf++ = '.';
|
|
|
|
/* Leading zeros don't count towards 'ndigit' */
|
|
while (decpt < 0)
|
|
{
|
|
*buf++ = '0';
|
|
decpt++;
|
|
}
|
|
|
|
/* Print rest of stuff */
|
|
while (*p && ndigit > 0)
|
|
{
|
|
*buf++ = *p++;
|
|
ndigit--;
|
|
}
|
|
/* And trailing zeros */
|
|
if (dot)
|
|
{
|
|
while (ndigit > 0)
|
|
{
|
|
*buf++ = '0';
|
|
ndigit--;
|
|
}
|
|
}
|
|
}
|
|
*buf++ = 0;
|
|
}
|
|
|
|
return save;
|
|
}
|
|
|
|
char *
|
|
_dcvt (struct _reent *ptr,
|
|
char *buffer,
|
|
double invalue,
|
|
int precision,
|
|
int width,
|
|
char type,
|
|
int dot)
|
|
{
|
|
switch (type)
|
|
{
|
|
case 'f':
|
|
case 'F':
|
|
print_f (ptr, buffer, invalue, precision, type, precision == 0 ? dot : 1, 3);
|
|
break;
|
|
case 'g':
|
|
case 'G':
|
|
if (precision == 0)
|
|
precision = 1;
|
|
_gcvt (ptr, invalue, precision, buffer, type, dot);
|
|
break;
|
|
case 'e':
|
|
case 'E':
|
|
print_e (ptr, buffer, invalue, precision, type, dot);
|
|
}
|
|
return buffer;
|
|
}
|