405 lines
11 KiB
C
405 lines
11 KiB
C
/****************************************************************************
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* libs/libc/stdio/lib_libdtoa.c
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*
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* This file was ported to NuttX by Yolande Cates.
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*
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdbool.h>
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#include <math.h>
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#include <assert.h>
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#include <nuttx/arch.h>
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#include "libc.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#ifndef MIN
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# define MIN(a,b) (((a) < (b)) ? (a) : (b))
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#endif
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#ifndef MAX
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# define MAX(a,b) (((a) > (b)) ? (a) : (b))
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#endif
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/* Use the maximim precision with %g format if no precision is specified.
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* NOTE: This may result in numbers with precision that exceeds the
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* precision of type double.
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*/
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#define DOUBLE_PRECISON_MAX 15
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/* Use a default precision of 6 for the %f format if no precision is
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* specified.
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*/
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#define DEFAULT_PRECISON 6
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: zeroes
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*
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* Description:
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* Print the specified number of zeres
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*
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****************************************************************************/
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static void zeroes(FAR struct lib_outstream_s *obj, int nzeroes)
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{
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int i;
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for (i = nzeroes; i > 0; i--)
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{
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lib_stream_putc(obj, '0');
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}
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}
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/****************************************************************************
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* Name: truncate_zeroes
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*
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* Description:
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* Adjust the string length to eliminate zeros in the fractional part of
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* the string.
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*
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****************************************************************************/
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static inline int truncate_zeroes(FAR char *digits, int expt, int numlen)
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{
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for (; numlen > expt && digits[numlen - 1] == '0'; numlen--)
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{
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}
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return numlen;
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}
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/****************************************************************************
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* Name: lib_dtoa_string
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*
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* Description:
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* Print the specified string
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*
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****************************************************************************/
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static void lib_dtoa_string(FAR struct lib_outstream_s *obj, const char *str)
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{
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while (*str)
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{
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lib_stream_putc(obj, *str++);
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}
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}
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/****************************************************************************
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* Name: lib_dtoa
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*
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* Description:
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* This is part of lib_vsprintf(). It handles the floating point formats.
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* This version supports only the %f (with precision). If no precision
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* was provided in the format, this will use precision == 0 which is
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* probably not what you want.
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*
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* Input Parameters:
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* obj - The output stream object
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* fmt - The format character. Not used 'f' is always assumed
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* prec - The number of digits to the right of the decimal point. If no
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* precision is provided in the format, this will be zero. And,
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* unfortunately in this case, it will be treated literally as
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* a precision of zero.
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* flags - Only ALTFORM and SHOWPLUS flags are supported. ALTFORM only
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* applies if prec == 0 which is not supported anyway.
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* value - The floating point value to convert.
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*
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****************************************************************************/
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static void lib_dtoa(FAR struct lib_outstream_s *obj, int fmt, int prec,
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uint16_t flags, double value)
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{
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FAR char *digits; /* String returned by __dtoa */
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FAR char *rve; /* Points to the end of the return value */
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bool notrailing; /* True: No trailing zeros */
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int expt; /* Integer value of exponent */
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int numlen; /* Actual number of digits returned by cvt */
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int nchars; /* Number of characters to print */
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int dsgn; /* Unused sign indicator */
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int i;
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/* Set to default precision if none specified */
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notrailing = false;
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if (!IS_HASDOT(flags) && prec == 0)
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{
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if (IS_NOTRAILINGZERO(flags))
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{
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prec = DOUBLE_PRECISON_MAX;
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notrailing = true;
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}
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else
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{
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prec = DEFAULT_PRECISON;
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}
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}
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/* Special handling for NaN and Infinity */
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if (isnan(value))
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{
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lib_dtoa_string(obj, "NaN");
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return;
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}
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if (isinf(value))
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{
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if (value < 0.0)
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{
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lib_stream_putc(obj, '-');
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}
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lib_dtoa_string(obj, "Infinity");
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return;
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}
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/* Non-zero... positive or negative */
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if (value < 0)
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{
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value = -value;
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SET_NEGATE(flags);
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}
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/* Perform the conversion */
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digits = __dtoa(value, 3, prec, &expt, &dsgn, &rve);
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numlen = rve - digits;
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/* If we are going to truncate trailing zeros, then make sure we have not
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* exceeded the precision of type double.
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*/
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if (notrailing && numlen > DOUBLE_PRECISON_MAX)
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{
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/* Make sure there are fractional digits to truncate */
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if (expt <= DOUBLE_PRECISON_MAX)
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{
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numlen = DOUBLE_PRECISON_MAX;
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}
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else
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{
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numlen = expt;
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}
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/* Shortening the string probably now exposes some trailing zeroes */
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numlen = truncate_zeroes(digits, expt, numlen);
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}
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/* Avoid precision error from missing trailing zeroes */
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numlen = MAX(expt, numlen);
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if (IS_NEGATE(flags))
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{
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lib_stream_putc(obj, '-');
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}
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else if (IS_SHOWPLUS(flags))
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{
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lib_stream_putc(obj, '+');
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}
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/* Special case exact zero or the case where the number is smaller than
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* the print precision.
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*/
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if (value == 0.0 || (expt < (notrailing ? 0 : -prec)))
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{
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/* kludge for __dtoa irregularity */
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lib_stream_putc(obj, '0');
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/* A decimal point is printed only in the alternate form or if a
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* particular precision is requested.
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*/
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if ((prec > 0 && !notrailing) || IS_ALTFORM(flags))
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{
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lib_stream_putc(obj, '.');
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/* Always print at least one digit to the right of the decimal
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* point.
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*/
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if (notrailing)
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{
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prec = MAX(1, numlen);
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}
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else
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{
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prec = MAX(1, prec);
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}
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}
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}
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/* A non-zero value will be printed */
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else
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{
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/* Handle the case where the value is less than 1.0 (in magnitude) and
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* will need a leading zero.
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*/
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if (expt <= 0)
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{
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/* Print a single zero to the left of the decimal point */
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lib_stream_putc(obj, '0');
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/* Print the decimal point */
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lib_stream_putc(obj, '.');
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/* Print any leading zeros to the right of the decimal point */
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if (expt < 0 || !notrailing)
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{
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nchars = MIN(-expt, prec);
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zeroes(obj, nchars);
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prec -= nchars;
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}
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}
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/* Handle the general case where the value is greater than 1.0 (in
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* magnitude).
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*/
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else
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{
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/* Print the integer part to the left of the decimal point */
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for (i = expt; i > 0; i--)
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{
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if (*digits != '\0')
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{
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lib_stream_putc(obj, *digits);
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digits++;
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}
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else
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{
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lib_stream_putc(obj, '0');
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}
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}
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/* Get the length of the fractional part */
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numlen -= expt;
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/* If there is no fractional part, then a decimal point is printed
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* only in the alternate form or if a particular precision is
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* requested.
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*/
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if (numlen > 0 || (prec > 0 && !notrailing) ||
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IS_ALTFORM(flags))
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{
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/* Print the decimal point */
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lib_stream_putc(obj, '.');
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/* Always print at least one digit to the right of the decimal
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* point.
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*/
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if (notrailing)
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{
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prec = MAX(1, numlen);
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}
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else
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{
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prec = MAX(1, prec);
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}
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}
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}
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/* If a precision was specified, then limit the number digits to the
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* right of the decimal point.
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*/
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if (prec > 0)
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{
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nchars = MIN(numlen, prec);
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}
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else
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{
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nchars = numlen;
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}
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/* Print the fractional part to the right of the decimal point */
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for (i = nchars; i > 0; i--)
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{
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lib_stream_putc(obj, *digits);
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digits++;
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}
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/* Decrement to get the number of trailing zeroes to print */
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prec -= nchars;
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}
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/* Finally, print any trailing zeroes */
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if (!notrailing)
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{
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zeroes(obj, prec);
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}
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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