git.sur5r.net Git - cc65/blob - libsrc/common/strftime.c

   1 /*****************************************************************************/
   2 /*                                                                           */
   3 /*                                strftime.c                                 */
   4 /*                                                                           */
   5 /*      Convert broken down time to a string in a user specified format      */
   6 /*                                                                           */
   7 /*                                                                           */
   8 /*                                                                           */
   9 /* (C) 2002      Ullrich von Bassewitz                                       */
  10 /*               Wacholderweg 14                                             */
  11 /*               D-70597 Stuttgart                                           */
  12 /* EMail:        uz@musoftware.de                                            */
  13 /*                                                                           */
  14 /*                                                                           */
  15 /* This software is provided 'as-is', without any expressed or implied       */
  16 /* warranty.  In no event will the authors be held liable for any damages    */
  17 /* arising from the use of this software.                                    */
  18 /*                                                                           */
  19 /* Permission is granted to anyone to use this software for any purpose,     */
  20 /* including commercial applications, and to alter it and redistribute it    */
  21 /* freely, subject to the following restrictions:                            */
  22 /*                                                                           */
  23 /* 1. The origin of this software must not be misrepresented; you must not   */
  24 /*    claim that you wrote the original software. If you use this software   */
  25 /*    in a product, an acknowledgment in the product documentation would be  */
  26 /*    appreciated but is not required.                                       */
  27 /* 2. Altered source versions must be plainly marked as such, and must not   */
  28 /*    be misrepresented as being the original software.                      */
  29 /* 3. This notice may not be removed or altered from any source              */
  30 /*    distribution.                                                          */
  31 /*                                                                           */
  32 /*****************************************************************************/
  33
  34
  35
  36 #include <string.h>
  37 #include <stdio.h>
  38 #include <time.h>
  39
  40
  41
  42 /* Use static local variables for speed */
  43 #pragma static-locals (on);
  44
  45
  46
  47 /*****************************************************************************/
  48 /*                                   Code                                    */
  49 /*****************************************************************************/
  50
  51
  52
  53 size_t __fastcall__ strftime (char* buf, size_t bufsize, const char* format,
  54                               const struct tm* tm)
  55 {
  56     static const char* const days[7] = {
  57         "Sunday",   "Monday", "Tuesday", "Wednesday",
  58         "Thursday", "Friday", "Saturday"
  59     };
  60     static const char* const months[12] = {
  61         "January", "February", "March", "April", "May", "June",
  62         "July", "August", "September", "October", "November", "December"
  63     };
  64
  65     unsigned    count;
  66     unsigned    len;
  67     char        c;
  68     char        arg[40];
  69     const char* argptr;
  70
  71     /* Copy until we reach the end of the format string or a format specifier */
  72     count = 0;
  73     while (1) {
  74         if (count >= bufsize) {
  75             /* Not enough buffer space available */
  76             return 0;
  77         }
  78         if ((c = *format++) == '\0') {
  79             /* End of format string reached */
  80             *buf = '\0';
  81             return count;
  82         }
  83         if (c == '%') {
  84             /* Format specifier */
  85             argptr = arg;
  86             switch (*format++) {
  87
  88                 case '%':
  89                     arg[0] = '%';
  90                     arg[1] = '\0';
  91                     break;
  92
  93                 case 'A':
  94                     argptr = days[tm->tm_wday];
  95                     break;
  96
  97                 case 'B':
  98                     argptr = months[tm->tm_mon];
  99                     break;
 100
 101                 case 'D':
 102                     sprintf (arg, "%02d/%02d/%02d", tm->tm_mon + 1,
 103                              tm->tm_mday, tm->tm_year % 100);
 104                     break;
 105
 106                 case 'F':
 107                     /* C99 */
 108                     sprintf (arg, "%04d-%02d-%02d", tm->tm_year + 1900,
 109                              tm->tm_mon + 1, tm->tm_mday);
 110                     break;
 111
 112                 case 'H':
 113                     sprintf (arg, "%02d", tm->tm_hour);
 114                     break;
 115
 116                 case 'I':
 117                     sprintf (arg, "%02d", (tm->tm_hour + 11) % 12 + 1);
 118                     break;
 119
 120                 case 'M':
 121                     sprintf (arg, "%02d", tm->tm_min);
 122                     break;
 123
 124                 case 'P':
 125                     /* GNU extension */
 126                     argptr = (tm->tm_hour >= 12)? "pm" : "am";
 127                     break;
 128
 129                 case 'S':
 130                     sprintf (arg, "%02d", tm->tm_sec);
 131                     break;
 132
 133                 case 'U':
 134                     sprintf (arg, "%02d", (tm->tm_yday + 7 - tm->tm_wday) / 7);
 135                     break;
 136
 137                 case 'W':
 138                     sprintf (arg, "%02d",
 139                              (tm->tm_yday + 7 - (tm->tm_wday? tm->tm_wday - 1 : 6)) / 7);
 140                     break;
 141
 142                 case 'X':
 143                     sprintf (arg, "%02d:%02d:%02d", tm->tm_hour,
 144                              tm->tm_min, tm->tm_sec);
 145                     break;
 146
 147                 case 'Y':
 148                     sprintf (arg, "%4d", tm->tm_year + 1900);
 149                     break;
 150
 151                 case 'Z':
 152                     argptr = tm->tm_isdst? _tz.dstname : _tz.tzname;
 153                     break;
 154
 155                 case 'a':
 156                     sprintf (arg, "%.3s", days[tm->tm_wday]);
 157                     break;
 158
 159                 case 'b':
 160                     sprintf (arg, "%.3s", months[tm->tm_mon]);
 161                     break;
 162
 163                 case 'c':
 164                     sprintf (arg, "%.3s %.3s%3d %02d:%02d:%02d %d",
 165                              days[tm->tm_wday], months[tm->tm_mon],
 166                              tm->tm_mday, tm->tm_hour, tm->tm_min,
 167                              tm->tm_sec, tm->tm_year + 1900);
 168                     break;
 169
 170                 case 'd':
 171                     sprintf (arg, "%02d", tm->tm_mday);
 172                     break;
 173
 174                 case 'j':
 175                     sprintf (arg, "%03d", tm->tm_yday + 1);
 176                     break;
 177
 178                 case 'm':
 179                     sprintf (arg, "%02d", tm->tm_mon + 1);
 180                     break;
 181
 182                 case 'p':
 183                     argptr = (tm->tm_hour >= 12)? "PM" : "AM";
 184                     break;
 185
 186                 case 'w':
 187                     sprintf (arg, "%d", tm->tm_wday);
 188                     break;
 189
 190                 case 'x':
 191                     sprintf (arg, "%04d-%02d-%02d", tm->tm_year + 1900,
 192                              tm->tm_mon + 1, tm->tm_mday);
 193                     break;
 194
 195                 case 'y':
 196                     sprintf (arg, "%02d", tm->tm_year % 100);
 197                     break;
 198
 199                 default:
 200                     /* Unknown format specifier, convert to empty string */
 201                     arg[0] = '\0';
 202                     break;
 203             }
 204
 205             /* Check if we have enough space to copy the argument string */
 206             len = strlen (argptr);
 207             count += len;
 208             if (count < bufsize) {
 209                 memcpy (buf, argptr, len);
 210                 buf += len;
 211             }
 212
 213         } else {
 214
 215             /* No format character, just copy */
 216             *buf++ = c;
 217             ++count;
 218
 219         }
 220     }
 221 }
 222
 223
 224