zephyr/clients/xzwrite/yank.c

   1 #include "xzwrite.h"
   2
   3 static Yank yank_buffer;
   4 extern Defaults defs;
   5
   6 static int read_index, write_index, highest;
   7
   8 void yank_init()
   9 {
  10      yank_buffer = (Yank) Malloc(defs.max_yanks*sizeof(YankRec),
  11                                    "while allocating yank buffer", NULL);
  12      (void) memset((char *) yank_buffer, 0, defs.max_yanks*sizeof(YankRec));
  13
  14      read_index = write_index = 0;
  15      highest = -1;
  16 }
  17
  18 Yank yank_prev()
  19 {
  20      if (highest == -1)
  21           return NULL;
  22
  23      if (--read_index < 0) read_index = highest;
  24      return &yank_buffer[read_index];
  25 }
  26
  27 Yank yank_next()
  28 {
  29      if (highest == -1)
  30           return NULL;
  31
  32      if (++read_index > highest) read_index = 0;
  33      return &yank_buffer[read_index];
  34 }
  35
  36 void yank_store(dest, msg)
  37    Dest dest;
  38    char *msg;
  39 {
  40      yank_buffer[write_index].dest = *dest;
  41      if (yank_buffer[write_index].msg)
  42          free(yank_buffer[write_index].msg);
  43      yank_buffer[write_index].msg = (char *) Malloc(strlen(msg) + 1,
  44                                                     "while yanking message",
  45                                                     NULL);
  46      strcpy(yank_buffer[write_index].msg, msg);
  47
  48      /*
  49       * read_index  = write_index + 1 so that if I follow the store by
  50       * a yank_prev I will get the message just stored (since
  51       * read_index is decremented before being used).  If I do a
  52       * yank_next, then read_index will be > highest and reset to zero.
  53       */
  54      read_index = write_index + 1;
  55      if (write_index > highest)
  56           highest = write_index;
  57      write_index = (write_index + 1) % defs.max_yanks;
  58 }