1 /**************************************************************** 2 * 3 * The author of this software is David M. Gay. 4 * 5 * Copyright (c) 1991, 1996 by Lucent Technologies. 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose without fee is hereby granted, provided that this entire notice 9 * is included in all copies of any software which is or includes a copy 10 * or modification of this software and in all copies of the supporting 11 * documentation for such software. 12 * 13 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED 14 * WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR LUCENT MAKES ANY 15 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY 16 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. 17 * 18 ***************************************************************/ 19 20 /* g_fmt(buf,x) stores the closest decimal approximation to x in buf; 21 * it suffices to declare buf 22 * char buf[32]; 23 */ 24 25 #include "dmg_fp.h" 26 27 namespace dmg_fp { 28 29 char * 30 g_fmt(register char *b, double x) 31 { 32 register int i, k; 33 register char *s; 34 int decpt, j, sign; 35 char *b0, *s0, *se; 36 37 b0 = b; 38 #ifdef IGNORE_ZERO_SIGN 39 if (!x) { 40 *b++ = '0'; 41 *b = 0; 42 goto done; 43 } 44 #endif 45 s = s0 = dtoa(x, 0, 0, &decpt, &sign, &se); 46 if (sign) 47 *b++ = '-'; 48 if (decpt == 9999) /* Infinity or Nan */ { 49 while((*b++ = *s++)) {} 50 goto done0; 51 } 52 if (decpt <= -4 || decpt > se - s + 5) { 53 *b++ = *s++; 54 if (*s) { 55 *b++ = '.'; 56 while((*b = *s++)) 57 b++; 58 } 59 *b++ = 'e'; 60 /* sprintf(b, "%+.2d", decpt - 1); */ 61 if (--decpt < 0) { 62 *b++ = '-'; 63 decpt = -decpt; 64 } 65 else 66 *b++ = '+'; 67 for(j = 2, k = 10; 10*k <= decpt; j++, k *= 10) {} 68 for(;;) { 69 i = decpt / k; 70 *b++ = i + '0'; 71 if (--j <= 0) 72 break; 73 decpt -= i*k; 74 decpt *= 10; 75 } 76 *b = 0; 77 } 78 else if (decpt <= 0) { 79 *b++ = '.'; 80 for(; decpt < 0; decpt++) 81 *b++ = '0'; 82 while((*b++ = *s++)) {} 83 } 84 else { 85 while((*b = *s++)) { 86 b++; 87 if (--decpt == 0 && *s) 88 *b++ = '.'; 89 } 90 for(; decpt > 0; decpt--) 91 *b++ = '0'; 92 *b = 0; 93 } 94 done0: 95 freedtoa(s0); 96 #ifdef IGNORE_ZERO_SIGN 97 done: 98 #endif 99 return b0; 100 } 101 102 } // namespace dmg_fp 103
