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