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px4-firmware/nuttx/lib/stdio/lib_libdtoa.c

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/****************************************************************************
* lib/unistd/lib_libdtoa.c
*
* This file was ported to NuttX by Yolande Cates.
*
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define MAXEXP 308
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static char* cvt(double value, int ndigits, int flags, char *sign,
int *decpt, int ch, int *length);
static int exponent(char *p0, int exp, int fmtch);
/****************************************************************************
* Global Constant Data
****************************************************************************/
/****************************************************************************
* Global Variables
****************************************************************************/
/****************************************************************************
* Private Constant Data
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: cvt
****************************************************************************/
static char* cvt(double value, int ndigits, int flags, char *sign,
int *decpt, int ch, int *length)
{
int mode, dsgn;
char *digits, *bp, *rve;
if (ch == 'f')
{
mode = 3; /* ndigits after the decimal point */
}
else
{
/* To obtain ndigits after the decimal point for the 'e' and 'E'
* formats, round to ndigits + 1 significant figures.
*/
if (ch == 'e' || ch == 'E')
{
ndigits++;
}
mode = 2; /* ndigits significant digits */
}
if (value < 0)
{
value = -value;
*sign = '-';
}
else
{
*sign = '\000';
}
digits = __dtoa(value, mode, ndigits, decpt, &dsgn, &rve);
if ((ch != 'g' && ch != 'G') || IS_ALTFORM(flags))
{
/* Print trailing zeros */
bp = digits + ndigits;
if (ch == 'f')
{
if (*digits == '0' && value)
{
*decpt = -ndigits + 1;
}
bp += *decpt;
}
if (value == 0)
{
/* kludge for __dtoa irregularity */
rve = bp;
}
while (rve < bp)
{
*rve++ = '0';
}
}
*length = rve - digits;
return digits;
}
/****************************************************************************
* Name: exponent
****************************************************************************/
static int exponent(FAR char *p0, int exp, int fmtch)
{
FAR char *p;
FAR char *t;
char expbuf[MAXEXP];
p = p0;
*p++ = fmtch;
if (exp < 0)
{
exp = -exp;
*p++ = '-';
}
else
{
*p++ = '+';
}
t = expbuf + MAXEXP;
if (exp > 9)
{
do
{
*--t = (exp % 10) + '0';
}
while ((exp /= 10) > 9);
*--t = exp + '0';
for (; t < expbuf + MAXEXP; *p++ = *t++);
}
else
{
*p++ = '0';
*p++ = exp + '0';
}
return (p - p0);
}
/****************************************************************************
* Name: lib_dtoa
*
* Description:
* This is part of lib_vsprintf(). It handles the floating point formats.
*
****************************************************************************/
static void lib_dtoa(FAR struct lib_outstream_s *obj, int ch, int prec,
uint8_t flags, double _double)
{
FAR char *cp; /* Handy char pointer (short term usage) */
FAR char *cp_free = NULL; /* BIONIC: copy of cp to be freed after usage */
char expstr[7]; /* Buffer for exponent string */
char sign; /* Temporary negative sign for floats */
int expt; /* Integer value of exponent */
int expsize = 0; /* Character count for expstr */
int ndig; /* Actual number of digits returned by cvt */
int size; /* Size of converted field or string */
int i;
cp = cvt(_double, prec, flags, &sign, &expt, ch, &ndig);
cp_free = cp;
if (ch == 'g' || ch == 'G')
{
/* 'g' or 'G' fmt */
if (expt <= -4 || expt > prec)
{
ch = (ch == 'g') ? 'e' : 'E';
}
else
{
ch = 'g';
}
}
if (ch <= 'e')
{
/* 'e' or 'E' fmt */
--expt;
expsize = exponent(expstr, expt, ch);
size = expsize + ndig;
if (ndig > 1 || IS_ALTFORM(flags))
{
++size;
}
}
else if (ch == 'f')
{
/* f fmt */
if (expt > 0)
{
size = expt;
if (prec || IS_ALTFORM(flags))
{
size += prec + 1;
}
}
else /* "0.X" */
{
size = prec + 2;
}
}
else if (expt >= ndig)
{
/* fixed g fmt */
size = expt;
if (IS_ALTFORM(flags))
{
++size;
}
}
else
{
size = ndig + (expt > 0 ? 1 : 2 - expt);
}
if (sign)
{
obj->put(obj, '-');
}
if (_double == 0)
{
/* kludge for __dtoa irregularity */
obj->put(obj, '0');
if (expt < ndig || IS_ALTFORM(flags))
{
obj->put(obj, '.');
i = ndig - 1;
while (i > 0)
{
obj->put(obj, '0');
i--;
}
}
}
else if (expt <= 0)
{
obj->put(obj, '0');
obj->put(obj, '.');
i = ndig;
while (i > 0)
{
obj->put(obj, *cp);
i--;
cp++;
}
}
else if (expt >= ndig)
{
i = ndig;
while (i > 0)
{
obj->put(obj, *cp);
i--;
cp++;
}
i = expt - ndig;
while (i > 0)
{
obj->put(obj, '0');
i--;
}
if (IS_ALTFORM(flags))
{
obj->put(obj, '.');
}
}
else
{
/* print the integer */
i = expt;
while (i > 0)
{
obj->put(obj, *cp);
i--;
cp++;
}
/* print the decimal place */
obj->put(obj, '.');
/* print the decimal */
i = ndig - expt;
while (i > 0)
{
obj->put(obj, *cp);
i--;
cp++;
}
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
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