lang/fortran/comp/cds.c

   1 /****************************************************************
   2 Copyright 1990 by AT&T Bell Laboratories and Bellcore.
   3
   4 Permission to use, copy, modify, and distribute this software
   5 and its documentation for any purpose and without fee is hereby
   6 granted, provided that the above copyright notice appear in all
   7 copies and that both that the copyright notice and this
   8 permission notice and warranty disclaimer appear in supporting
   9 documentation, and that the names of AT&T Bell Laboratories or
  10 Bellcore or any of their entities not be used in advertising or
  11 publicity pertaining to distribution of the software without
  12 specific, written prior permission.
  13
  14 AT&T and Bellcore disclaim all warranties with regard to this
  15 software, including all implied warranties of merchantability
  16 and fitness.  In no event shall AT&T or Bellcore be liable for
  17 any special, indirect or consequential damages or any damages
  18 whatsoever resulting from loss of use, data or profits, whether
  19 in an action of contract, negligence or other tortious action,
  20 arising out of or in connection with the use or performance of
  21 this software.
  22 ****************************************************************/
  23
  24 /* Put strings representing decimal floating-point numbers
  25  * into canonical form: always have a decimal point or
  26  * exponent field; if using an exponent field, have the
  27  * number before it start with a digit and decimal point
  28  * (if the number has more than one digit); only have an
  29  * exponent field if it saves space.
  30  *
  31  * Arrange that the return value, rv, satisfies rv[0] == '-' || rv[-1] == '-' .
  32  */
  33
  34 #include "sysdep.h"
  35
  36  char *
  37 cds(s, z0)
  38  char *s, *z0;
  39 {
  40         int ea, esign, et, i, k, nd = 0, sign = 0, tz;
  41         char c, *z;
  42         char ebuf[24];
  43         long ex = 0;
  44         static char etype[Table_size], *db;
  45         static int dblen = 64;
  46
  47         if (!db) {
  48                 etype['E'] = 1;
  49                 etype['e'] = 1;
  50                 etype['D'] = 1;
  51                 etype['d'] = 1;
  52                 etype['+'] = 2;
  53                 etype['-'] = 3;
  54                 db = Alloc(dblen);
  55                 }
  56
  57         while((c = *s++) == '0');
  58         if (c == '-')
  59                 { sign = 1; c = *s++; }
  60         else if (c == '+')
  61                 c = *s++;
  62         k = strlen(s) + 2;
  63         if (k >= dblen) {
  64                 do dblen <<= 1;
  65                         while(k >= dblen);
  66                 free(db);
  67                 db = Alloc(dblen);
  68                 }
  69         if (etype[(unsigned char)c] >= 2)
  70                 while(c == '0') c = *s++;
  71         tz = 0;
  72         while(c >= '0' && c <= '9') {
  73                 if (c == '0')
  74                         tz++;
  75                 else {
  76                         if (nd)
  77                                 for(; tz; --tz)
  78                                         db[nd++] = '0';
  79                         else
  80                                 tz = 0;
  81                         db[nd++] = c;
  82                         }
  83                 c = *s++;
  84                 }
  85         ea = -tz;
  86         if (c == '.') {
  87                 while((c = *s++) >= '0' && c <= '9') {
  88                         if (c == '0')
  89                                 tz++;
  90                         else {
  91                                 if (tz) {
  92                                         ea += tz;
  93                                         if (nd)
  94                                                 for(; tz; --tz)
  95                                                         db[nd++] = '0';
  96                                         else
  97                                                 tz = 0;
  98                                         }
  99                                 db[nd++] = c;
 100                                 ea++;
 101                                 }
 102                         }
 103                 }
 104         if (et = etype[(unsigned char)c]) {
 105                 esign = et == 3;
 106                 c = *s++;
 107                 if (et == 1) {
 108                         if(etype[(unsigned char)c] > 1) {
 109                                 if (c == '-')
 110                                         esign = 1;
 111                                 c = *s++;
 112                                 }
 113                         }
 114                 while(c >= '0' && c <= '9') {
 115                         ex = 10*ex + (c - '0');
 116                         c = *s++;
 117                         }
 118                 if (esign)
 119                         ex = -ex;
 120                 }
 121         /* debug */ if (c)
 122         /* debug*/      Fatal("unexpected character in cds");
 123         ex -= ea;
 124         if (!nd) {
 125                 if (!z0)
 126                         z0 = mem(4,0);
 127                 strcpy(z0, "-0.");
 128                 sign = 0;
 129                 }
 130         else if (ex > 2 || ex + nd < -2) {
 131                 sprintf(ebuf, "%ld", ex + nd - 1);
 132                 k = strlen(ebuf) + nd + 3;
 133                 if (nd > 1)
 134                         k++;
 135                 if (!z0)
 136                         z0 = mem(k,0);
 137                 z = z0;
 138                 *z++ = '-';
 139                 *z++ = *db;
 140                 if (nd > 1) {
 141                         *z++ = '.';
 142                         for(k = 1; k < nd; k++)
 143                                 *z++ = db[k];
 144                         }
 145                 *z++ = 'e';
 146                 strcpy(z, ebuf);
 147                 }
 148         else {
 149                 k = (int)(ex + nd);
 150                 i = nd + 3;
 151                 if (k < 0)
 152                         i -= k;
 153                 else if (ex > 0)
 154                         i += ex;
 155                 if (!z0)
 156                         z0 = mem(i,0);
 157                 z = z0;
 158                 *z++ = '-';
 159                 if (ex >= 0) {
 160                         for(k = 0; k < nd; k++)
 161                                 *z++ = db[k];
 162                         while(--ex >= 0)
 163                                 *z++ = '0';
 164                         *z++ = '.';
 165                         }
 166                 else {
 167                         for(i = 0; i < k;)
 168                                 *z++ = db[i++];
 169                         *z++ = '.';
 170                         while(++k <= 0)
 171                                 *z++ = '0';
 172                         while(i < nd)
 173                                 *z++ = db[i++];
 174                         }
 175                 *z = 0;
 176                 }
 177         return sign ? z0 : z0+1;
 178         }