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/* Copyright (c) 1993-2008 by Richard Kelsey and Jonathan Rees.
See file COPYING. */
#include <stdlib.h>
#include <string.h>
extern int s48_dragon(char *buf, double v);
extern void s48_free_init(void);
size_t
s48_double_to_string(char *dest, double v)
{
char raw[33];
char *buf = dest;
char *digits = raw;
int exponent = s48_dragon(raw, v);
int digit_count = strlen(raw);
if (*digits == '#') /* infinity or NaN */
{
strcpy(dest, digits);
return digit_count;
}
if (*digits == '-')
{
*buf++ = '-';
++digits;
--digit_count;
}
if ((exponent <= -4) || (exponent > (digit_count + 7)))
/* print with explicit exponent */
{
int decimal_point = exponent;
*buf++ = *digits++;
if (*digits)
{
*buf++ = '.';
while (*digits)
*buf++ = *digits++;
}
/* exponent */
*buf++ = 'e';
if (decimal_point < 0)
{
*buf++ = '-';
decimal_point = -decimal_point;
}
{
int power_of_10 = 1;
while (decimal_point >= (10*power_of_10))
power_of_10 *= 10;
while (power_of_10 > 0)
{
int digit = decimal_point / power_of_10;
*buf++ = digit + '0';
decimal_point -= digit * power_of_10;
power_of_10 /= 10;
}
}
*buf = '\0';
}
else if (exponent < 0)
/* 0.<something> */
{
*buf++ = '0';
*buf++ = '.';
++exponent;
while (exponent < 0)
{
*buf++ = '0';
++exponent;
}
while (*digits)
*buf++ = *digits++;
*buf = '\0';
}
else
/* <something>.<something> */
{
while (*digits)
{
*buf++ = *digits++;
if (exponent == 0)
*buf++ = '.';
--exponent;
}
if (exponent >= 0)
{
while (exponent >= 0)
{
*buf++ = '0';
--exponent;
}
*buf++ = '.';
*buf++ = '0';
}
else
{
if (exponent == -1)
*buf++ = '0';
}
*buf = '\0';
}
return buf - dest;
}
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