112 lines
2.4 KiB
C
112 lines
2.4 KiB
C
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/****************************************************************
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*
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* The author of this software is David M. Gay.
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*
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* Copyright (c) 1991, 1996 by Lucent Technologies.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose without fee is hereby granted, provided that this entire notice
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* is included in all copies of any software which is or includes a copy
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* or modification of this software and in all copies of the supporting
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* documentation for such software.
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*
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* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR LUCENT MAKES ANY
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* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
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* OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
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*
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***************************************************************/
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/* g_fmt(buf,x) stores the closest decimal approximation to x in buf;
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* it suffices to declare buf
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* char buf[32];
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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extern char *dtoa(double, int, int, int *, int *, char **);
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extern int g_fmt(char *, double, int);
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extern void freedtoa(char*);
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#ifdef __cplusplus
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}
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#endif
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int
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fpconv_g_fmt(char *b, double x, int precision)
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{
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register int i, k;
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register char *s;
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int decpt, j, sign;
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char *b0, *s0, *se;
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b0 = b;
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#ifdef IGNORE_ZERO_SIGN
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if (!x) {
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*b++ = '0';
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*b = 0;
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goto done;
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}
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#endif
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s = s0 = dtoa(x, 2, precision, &decpt, &sign, &se);
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if (sign)
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*b++ = '-';
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if (decpt == 9999) /* Infinity or Nan */ {
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while((*b++ = *s++));
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/* "b" is used to calculate the return length. Decrement to exclude the
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* Null terminator from the length */
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b--;
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goto done0;
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}
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if (decpt <= -4 || decpt > precision) {
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*b++ = *s++;
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if (*s) {
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*b++ = '.';
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while((*b = *s++))
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b++;
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}
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*b++ = 'e';
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/* sprintf(b, "%+.2d", decpt - 1); */
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if (--decpt < 0) {
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*b++ = '-';
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decpt = -decpt;
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}
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else
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*b++ = '+';
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for(j = 2, k = 10; 10*k <= decpt; j++, k *= 10);
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for(;;) {
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i = decpt / k;
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*b++ = i + '0';
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if (--j <= 0)
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break;
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decpt -= i*k;
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decpt *= 10;
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}
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*b = 0;
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}
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else if (decpt <= 0) {
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*b++ = '0';
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*b++ = '.';
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for(; decpt < 0; decpt++)
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*b++ = '0';
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while((*b++ = *s++));
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b--;
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}
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else {
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while((*b = *s++)) {
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b++;
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if (--decpt == 0 && *s)
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*b++ = '.';
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}
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for(; decpt > 0; decpt--)
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*b++ = '0';
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*b = 0;
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}
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done0:
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freedtoa(s0);
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#ifdef IGNORE_ZERO_SIGN
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done:
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#endif
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return b - b0;
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}
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