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119 lines
2.2 KiB
C
119 lines
2.2 KiB
C
/*
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* PROJECT: ReactOS CRT
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* LICENSE: See COPYING in the top level directory
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* PURPOSE: CRT's ecvt
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* FILE: lib/sdk/crt/stdlib/ecvt.c
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* PROGRAMERS: Gregor Schneider (parts based on ecvtbuf.c by DJ Delorie)
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*/
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#include <precomp.h>
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#define NUMBER_EFMT 18 /* sign, dot, null, 15 for alignment */
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/*
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* @implemented
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*/
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char *
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_ecvt (double value, int ndigits, int *decpt, int *sign)
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{
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static char ecvtbuf[DBL_MAX_10_EXP + 10];
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char *cvtbuf, *s, *d;
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if (ndigits < 0) ndigits = 0;
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s = cvtbuf = (char*)malloc(ndigits + NUMBER_EFMT);
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d = ecvtbuf;
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*sign = 0;
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*decpt = 0;
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if (cvtbuf == NULL)
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{
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return NULL;
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}
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sprintf(cvtbuf, "%-+.*E", ndigits, value);
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/* Treat special values */
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if (strncmp(s, "NaN", 3) == 0)
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{
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memcpy(ecvtbuf, s, 4);
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}
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else if (strncmp(s + 1, "Inf", 3) == 0)
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{
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memcpy(ecvtbuf, s, 5);
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}
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else
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{
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/* Set the sign */
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if (*s && *s == '-')
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{
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*sign = 1;
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}
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s++;
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/* Copy the first digit */
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if (*s && *s != '.')
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{
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if (d - ecvtbuf < ndigits)
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{
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*d++ = *s++;
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}
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else
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{
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s++;
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}
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}
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/* Skip the decimal point */
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if (*s && *s == '.')
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{
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s++;
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}
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/* Copy fractional digits */
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while (*s && *s != 'E')
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{
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if (d - ecvtbuf < ndigits)
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{
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*d++ = *s++;
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}
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else
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{
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s++;
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}
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}
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/* Skip the exponent */
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if (*s && *s == 'E')
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{
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s++;
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}
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/* Set the decimal point to the exponent value plus the one digit we copied */
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*decpt = atoi(s) + 1;
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/* Handle special decimal point cases */
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if (cvtbuf[1] == '0')
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{
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*decpt = 0;
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}
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if (ndigits < 1)
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{
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/* Need enhanced precision*/
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char* tbuf = (char*)malloc(NUMBER_EFMT);
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if (tbuf == NULL)
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{
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free(cvtbuf);
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return NULL;
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}
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sprintf(tbuf, "%-+.*E", ndigits + 2, value);
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if (tbuf[1] >= '5')
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{
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(*decpt)++;
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}
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free(tbuf);
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}
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/* Pad with zeroes */
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while (d - ecvtbuf < ndigits)
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{
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*d++ = '0';
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}
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/* Terminate */
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*d = '\0';
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}
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free(cvtbuf);
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return ecvtbuf;
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}
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