michael@0: /****************************************************************
michael@0:  *
michael@0:  * The author of this software is David M. Gay.
michael@0:  *
michael@0:  * Copyright (c) 1991, 1996 by Lucent Technologies.
michael@0:  *
michael@0:  * Permission to use, copy, modify, and distribute this software for any
michael@0:  * purpose without fee is hereby granted, provided that this entire notice
michael@0:  * is included in all copies of any software which is or includes a copy
michael@0:  * or modification of this software and in all copies of the supporting
michael@0:  * documentation for such software.
michael@0:  *
michael@0:  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
michael@0:  * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHOR NOR LUCENT MAKES ANY
michael@0:  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
michael@0:  * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
michael@0:  *
michael@0:  ***************************************************************/
michael@0: 
michael@0: /* g_fmt(buf,x) stores the closest decimal approximation to x in buf;
michael@0:  * it suffices to declare buf
michael@0:  *	char buf[32];
michael@0:  */
michael@0: 
michael@0: #include "dmg_fp.h"
michael@0: 
michael@0: namespace dmg_fp {
michael@0: 
michael@0:  char *
michael@0: g_fmt(register char *b, double x)
michael@0: {
michael@0: 	register int i, k;
michael@0: 	register char *s;
michael@0: 	int decpt, j, sign;
michael@0: 	char *b0, *s0, *se;
michael@0: 
michael@0: 	b0 = b;
michael@0: #ifdef IGNORE_ZERO_SIGN
michael@0: 	if (!x) {
michael@0: 		*b++ = '0';
michael@0: 		*b = 0;
michael@0: 		goto done;
michael@0: 		}
michael@0: #endif
michael@0: 	s = s0 = dtoa(x, 0, 0, &decpt, &sign, &se);
michael@0: 	if (sign)
michael@0: 		*b++ = '-';
michael@0: 	if (decpt == 9999) /* Infinity or Nan */ {
michael@0: 		while((*b++ = *s++)) {}
michael@0: 		goto done0;
michael@0: 		}
michael@0: 	if (decpt <= -4 || decpt > se - s + 5) {
michael@0: 		*b++ = *s++;
michael@0: 		if (*s) {
michael@0: 			*b++ = '.';
michael@0: 			while((*b = *s++))
michael@0: 				b++;
michael@0: 			}
michael@0: 		*b++ = 'e';
michael@0: 		/* sprintf(b, "%+.2d", decpt - 1); */
michael@0: 		if (--decpt < 0) {
michael@0: 			*b++ = '-';
michael@0: 			decpt = -decpt;
michael@0: 			}
michael@0: 		else
michael@0: 			*b++ = '+';
michael@0: 		for(j = 2, k = 10; 10*k <= decpt; j++, k *= 10) {}
michael@0: 		for(;;) {
michael@0: 			i = decpt / k;
michael@0: 			*b++ = i + '0';
michael@0: 			if (--j <= 0)
michael@0: 				break;
michael@0: 			decpt -= i*k;
michael@0: 			decpt *= 10;
michael@0: 			}
michael@0: 		*b = 0;
michael@0: 		}
michael@0: 	else if (decpt <= 0) {
michael@0: 		*b++ = '.';
michael@0: 		for(; decpt < 0; decpt++)
michael@0: 			*b++ = '0';
michael@0: 		while((*b++ = *s++)) {}
michael@0: 		}
michael@0: 	else {
michael@0: 		while((*b = *s++)) {
michael@0: 			b++;
michael@0: 			if (--decpt == 0 && *s)
michael@0: 				*b++ = '.';
michael@0: 			}
michael@0: 		for(; decpt > 0; decpt--)
michael@0: 			*b++ = '0';
michael@0: 		*b = 0;
michael@0: 		}
michael@0:  done0:
michael@0: 	freedtoa(s0);
michael@0: #ifdef IGNORE_ZERO_SIGN
michael@0:  done:
michael@0: #endif
michael@0: 	return b0;
michael@0: 	}
michael@0: 
michael@0: }  // namespace dmg_fp