map.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include "roff.h"
   4
   5 /* register, macro, or environments names with more than two characters */
   6 static char keys[NREGS][GNLEN];
   7 static int nkeys = 1;
   8 /* per starting character name lists */
   9 static int key_head[256];
  10 static int key_next[NREGS];
  11
  12 /* return the index of s in keys[]; insert it if not in keys[] */
  13 static int key_get(char *s)
  14 {
  15         int head = (unsigned char) s[0];
  16         int i = key_head[head];
  17         while (i > 0) {
  18                 if (!strcmp(keys[i], s))
  19                         return i;
  20                 i = key_next[i];
  21         }
  22         i = nkeys++;
  23         strcpy(keys[i], s);
  24         key_next[i] = key_head[head];
  25         key_head[head] = i;
  26         return i;
  27 }
  28
  29 /* map register names to [0..NREGS * 2) */
  30 int map(char *s)
  31 {
  32         if (n_cp || !s[1] || !s[2])
  33                 return REG(s[0], s[1]);
  34         return NREGS + key_get(s);
  35 }
  36
  37 /* returns a static buffer */
  38 char *map_name(int id)
  39 {
  40         static char map_buf[NMLEN];
  41         if (id >= NREGS)
  42                 return keys[id - NREGS];
  43         map_buf[0] = (id >> 8) & 0xff;
  44         map_buf[1] = id & 0xff;
  45         map_buf[2] = '\0';
  46         return map_buf;
  47 }