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nuttx/libs/libc/stdio/lib_libdtoa.c
Xiang Xiao 055f1f33eb libc/stream: Rename [lib_stream_](put|get) to [lib_stream_](putc|getc) 
to make the naming style consistent with each other

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
2022-12-05 14:27:55 +01:00

405 lines
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/****************************************************************************
* libs/libc/stdio/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
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <math.h>
#include <assert.h>
#include <nuttx/arch.h>
#include "libc.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#ifndef MIN
# define MIN(a,b) (a < b ? a : b)
#endif
#ifndef MAX
# define MAX(a,b) (a > b ? a : b)
#endif
/* Use the maximim precision with %g format if no precision is specified.
* NOTE: This may result in numbers with precision that exceeds the
* precision of type double.
*/
#define DOUBLE_PRECISON_MAX 15
/* Use a default precision of 6 for the %f format if no precision is
* specified.
*/
#define DEFAULT_PRECISON 6
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: zeroes
*
* Description:
* Print the specified number of zeres
*
****************************************************************************/
static void zeroes(FAR struct lib_outstream_s *obj, int nzeroes)
{
int i;
for (i = nzeroes; i > 0; i--)
{
lib_stream_putc(obj, '0');
}
}
/****************************************************************************
* Name: truncate_zeroes
*
* Description:
* Adjust the string length to eliminate zeros in the fractional part of
* the string.
*
****************************************************************************/
static inline int truncate_zeroes(FAR char *digits, int expt, int numlen)
{
for (; numlen > expt && digits[numlen - 1] == '0'; numlen--)
{
}
return numlen;
}
/****************************************************************************
* Name: lib_dtoa_string
*
* Description:
* Print the specified string
*
****************************************************************************/
static void lib_dtoa_string(FAR struct lib_outstream_s *obj, const char *str)
{
while (*str)
{
lib_stream_putc(obj, *str++);
}
}
/****************************************************************************
* Name: lib_dtoa
*
* Description:
* This is part of lib_vsprintf(). It handles the floating point formats.
* This version supports only the %f (with precision). If no precision
* was provided in the format, this will use precision == 0 which is
* probably not what you want.
*
* Input Parameters:
* obj - The output stream object
* fmt - The format character. Not used 'f' is always assumed
* prec - The number of digits to the right of the decimal point. If no
* precision is provided in the format, this will be zero. And,
* unfortunately in this case, it will be treated literally as
* a precision of zero.
* flags - Only ALTFORM and SHOWPLUS flags are supported. ALTFORM only
* applies if prec == 0 which is not supported anyway.
* value - The floating point value to convert.
*
****************************************************************************/
static void lib_dtoa(FAR struct lib_outstream_s *obj, int fmt, int prec,
uint16_t flags, double value)
{
FAR char *digits; /* String returned by __dtoa */
FAR char *rve; /* Points to the end of the return value */
bool notrailing; /* True: No trailing zeros */
int expt; /* Integer value of exponent */
int numlen; /* Actual number of digits returned by cvt */
int nchars; /* Number of characters to print */
int dsgn; /* Unused sign indicator */
int i;
/* Set to default precision if none specified */
notrailing = false;
if (!IS_HASDOT(flags) && prec == 0)
{
if (IS_NOTRAILINGZERO(flags))
{
prec = DOUBLE_PRECISON_MAX;
notrailing = true;
}
else
{
prec = DEFAULT_PRECISON;
}
}
/* Special handling for NaN and Infinity */
if (isnan(value))
{
lib_dtoa_string(obj, "NaN");
return;
}
if (isinf(value))
{
if (value < 0.0)
{
lib_stream_putc(obj, '-');
}
lib_dtoa_string(obj, "Infinity");
return;
}
/* Non-zero... positive or negative */
if (value < 0)
{
value = -value;
SET_NEGATE(flags);
}
/* Perform the conversion */
digits = __dtoa(value, 3, prec, &expt, &dsgn, &rve);
numlen = rve - digits;
/* If we are going to truncate trailing zeros, then make sure we have not
* exceeded the precision of type double.
*/
if (notrailing && numlen > DOUBLE_PRECISON_MAX)
{
/* Make sure there are fractional digits to truncate */
if (expt <= DOUBLE_PRECISON_MAX)
{
numlen = DOUBLE_PRECISON_MAX;
}
else
{
numlen = expt;
}
/* Shortening the string probably now exposes some trailing zeroes */
numlen = truncate_zeroes(digits, expt, numlen);
}
/* Avoid precision error from missing trailing zeroes */
numlen = MAX(expt, numlen);
if (IS_NEGATE(flags))
{
lib_stream_putc(obj, '-');
}
else if (IS_SHOWPLUS(flags))
{
lib_stream_putc(obj, '+');
}
/* Special case exact zero or the case where the number is smaller than
* the print precision.
*/
if (value == 0.0 || (expt < (notrailing ? 0 : -prec)))
{
/* kludge for __dtoa irregularity */
lib_stream_putc(obj, '0');
/* A decimal point is printed only in the alternate form or if a
* particular precision is requested.
*/
if ((prec > 0 && !notrailing) || IS_ALTFORM(flags))
{
lib_stream_putc(obj, '.');
/* Always print at least one digit to the right of the decimal
* point.
*/
if (notrailing)
{
prec = MAX(1, numlen);
}
else
{
prec = MAX(1, prec);
}
}
}
/* A non-zero value will be printed */
else
{
/* Handle the case where the value is less than 1.0 (in magnitude) and
* will need a leading zero.
*/
if (expt <= 0)
{
/* Print a single zero to the left of the decimal point */
lib_stream_putc(obj, '0');
/* Print the decimal point */
lib_stream_putc(obj, '.');
/* Print any leading zeros to the right of the decimal point */
if (expt < 0 || !notrailing)
{
nchars = MIN(-expt, prec);
zeroes(obj, nchars);
prec -= nchars;
}
}
/* Handle the general case where the value is greater than 1.0 (in
* magnitude).
*/
else
{
/* Print the integer part to the left of the decimal point */
for (i = expt; i > 0; i--)
{
if (*digits != '\0')
{
lib_stream_putc(obj, *digits);
digits++;
}
else
{
lib_stream_putc(obj, '0');
}
}
/* Get the length of the fractional part */
numlen -= expt;
/* If there is no fractional part, then a decimal point is printed
* only in the alternate form or if a particular precision is
* requested.
*/
if (numlen > 0 || (prec > 0 && !notrailing) ||
IS_ALTFORM(flags))
{
/* Print the decimal point */
lib_stream_putc(obj, '.');
/* Always print at least one digit to the right of the decimal
* point.
*/
if (notrailing)
{
prec = MAX(1, numlen);
}
else
{
prec = MAX(1, prec);
}
}
}
/* If a precision was specified, then limit the number digits to the
* right of the decimal point.
*/
if (prec > 0)
{
nchars = MIN(numlen, prec);
}
else
{
nchars = numlen;
}
/* Print the fractional part to the right of the decimal point */
for (i = nchars; i > 0; i--)
{
lib_stream_putc(obj, *digits);
digits++;
}
/* Decrement to get the number of trailing zeroes to print */
prec -= nchars;
}
/* Finally, print any trailing zeroes */
if (!notrailing)
{
zeroes(obj, prec);
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
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