gas/cond.c

   1 /* cond.c - conditional assembly pseudo-ops, and .include
   2    Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
   3
   4    This file is part of GAS, the GNU Assembler.
   5
   6    GAS is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    GAS is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GAS; see the file COPYING.  If not, write to
  18    the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 #include "as.h"
  21
  22 #include "obstack.h"
  23
  24 /* This is allocated to grow and shrink as .ifdef/.endif pairs are scanned. */
  25 struct obstack cond_obstack;
  26
  27 struct file_line
  28 {
  29   char *file;
  30   unsigned int line;
  31 };                              /* file_line */
  32
  33 /* This is what we push and pop. */
  34 struct conditional_frame
  35   {
  36     struct file_line if_file_line;      /* the source file & line number of the "if" */
  37     struct file_line else_file_line;    /* the source file & line of the "else" */
  38     struct conditional_frame *previous_cframe;
  39     int else_seen;              /* have we seen an else yet? */
  40     int ignoring;               /* if we are currently ignoring input. */
  41     int dead_tree;              /* if a conditional at a higher level is ignoring input. */
  42   };                            /* conditional_frame */
  43
  44 static void initialize_cframe PARAMS ((struct conditional_frame *cframe));
  45 static char *get_mri_string PARAMS ((int, int *));
  46
  47 static struct conditional_frame *current_cframe = NULL;
  48
  49 void
  50 s_ifdef (arg)
  51      int arg;
  52 {
  53   register char *name;          /* points to name of symbol */
  54   register struct symbol *symbolP;      /* Points to symbol */
  55   struct conditional_frame cframe;
  56
  57   SKIP_WHITESPACE ();           /* Leading whitespace is part of operand. */
  58   name = input_line_pointer;
  59
  60   if (!is_name_beginner (*name))
  61     {
  62       as_bad ("invalid identifier for \".ifdef\"");
  63       obstack_1grow (&cond_obstack, 0);
  64     }
  65   else
  66     {
  67       get_symbol_end ();
  68       ++input_line_pointer;
  69       symbolP = symbol_find (name);
  70
  71       initialize_cframe (&cframe);
  72       cframe.ignoring = cframe.dead_tree || !((symbolP != 0) ^ arg);
  73       current_cframe = (struct conditional_frame *) obstack_copy (&cond_obstack, &cframe, sizeof (cframe));
  74     }                           /* if a valid identifyer name */
  75
  76   return;
  77 }                               /* s_ifdef() */
  78
  79 void
  80 s_if (arg)
  81      int arg;
  82 {
  83   expressionS operand;
  84   struct conditional_frame cframe;
  85   int t;
  86
  87   SKIP_WHITESPACE ();           /* Leading whitespace is part of operand. */
  88   expression (&operand);
  89
  90   if (operand.X_op != O_constant)
  91     as_bad ("non-constant expression in \".if\" statement");
  92
  93   switch ((operatorT) arg)
  94     {
  95     case O_eq: t = operand.X_add_number == 0; break;
  96     case O_ne: t = operand.X_add_number != 0; break;
  97     case O_lt: t = operand.X_add_number < 0; break;
  98     case O_le: t = operand.X_add_number <= 0; break;
  99     case O_ge: t = operand.X_add_number >= 0; break;
 100     case O_gt: t = operand.X_add_number > 0; break;
 101     default:
 102       abort ();
 103     }
 104
 105   /* If the above error is signaled, this will dispatch
 106      using an undefined result.  No big deal.  */
 107   initialize_cframe (&cframe);
 108   cframe.ignoring = cframe.dead_tree || ! t;
 109   current_cframe = ((struct conditional_frame *)
 110                     obstack_copy (&cond_obstack, &cframe, sizeof (cframe)));
 111   return;
 112 }                               /* s_if() */
 113
 114 /* Get a string for the MRI IFC or IFNC pseudo-ops.  */
 115
 116 static char *
 117 get_mri_string (terminator, len)
 118      int terminator;
 119      int *len;
 120 {
 121   char *ret;
 122   char *s;
 123
 124   SKIP_WHITESPACE ();
 125   s = ret = input_line_pointer;
 126   if (*input_line_pointer == '\'')
 127     {
 128       ++s;
 129       ++input_line_pointer;
 130       while (! is_end_of_line[(unsigned char) *input_line_pointer])
 131         {
 132           *s++ = *input_line_pointer++;
 133           if (s[-1] == '\'')
 134             {
 135               if (*input_line_pointer != '\'')
 136                 break;
 137               ++input_line_pointer;
 138             }
 139         }
 140       SKIP_WHITESPACE ();
 141     }
 142   else
 143     {
 144       while (*input_line_pointer != terminator
 145              && ! is_end_of_line[(unsigned char) *input_line_pointer])
 146         ++input_line_pointer;
 147       s = input_line_pointer;
 148       while (s > ret && (s[-1] == ' ' || s[-1] == '\t'))
 149         --s;
 150     }
 151
 152   *len = s - ret;
 153   return ret;
 154 }
 155
 156 /* The MRI IFC and IFNC pseudo-ops.  */
 157
 158 void
 159 s_ifc (arg)
 160      int arg;
 161 {
 162   char *s1, *s2;
 163   int len1, len2;
 164   int res;
 165   struct conditional_frame cframe;
 166
 167   s1 = get_mri_string (',', &len1);
 168
 169   if (*input_line_pointer != ',')
 170     as_bad ("bad format for ifc or ifnc");
 171   else
 172     ++input_line_pointer;
 173
 174   s2 = get_mri_string (';', &len2);
 175
 176   res = len1 == len2 && strncmp (s1, s2, len1) == 0;
 177
 178   initialize_cframe (&cframe);
 179   cframe.ignoring = cframe.dead_tree || ! (res ^ arg);
 180   current_cframe = ((struct conditional_frame *)
 181                     obstack_copy (&cond_obstack, &cframe, sizeof (cframe)));
 182 }
 183
 184 void
 185 s_endif (arg)
 186      int arg;
 187 {
 188   struct conditional_frame *hold;
 189
 190   if (current_cframe == NULL)
 191     {
 192       as_bad ("\".endif\" without \".if\"");
 193     }
 194   else
 195     {
 196       hold = current_cframe;
 197       current_cframe = current_cframe->previous_cframe;
 198       obstack_free (&cond_obstack, hold);
 199     }                           /* if one pop too many */
 200
 201   return;
 202 }                               /* s_endif() */
 203
 204 void
 205 s_else (arg)
 206      int arg;
 207 {
 208   if (current_cframe == NULL)
 209     {
 210       as_bad (".else without matching .if - ignored");
 211
 212     }
 213   else if (current_cframe->else_seen)
 214     {
 215       as_bad ("duplicate \"else\" - ignored");
 216       as_bad_where (current_cframe->else_file_line.file,
 217                     current_cframe->else_file_line.line,
 218                     "here is the previous \"else\"");
 219       as_bad_where (current_cframe->if_file_line.file,
 220                     current_cframe->if_file_line.line,
 221                     "here is the previous \"if\"");
 222     }
 223   else
 224     {
 225       as_where (&current_cframe->else_file_line.file,
 226                 &current_cframe->else_file_line.line);
 227
 228       if (!current_cframe->dead_tree)
 229         {
 230           current_cframe->ignoring = !current_cframe->ignoring;
 231         }                       /* if not a dead tree */
 232
 233       current_cframe->else_seen = 1;
 234     }                           /* if error else do it */
 235
 236   return;
 237 }                               /* s_else() */
 238
 239 void
 240 s_ifeqs (arg)
 241      int arg;
 242 {
 243   as_bad ("ifeqs not implemented.");
 244
 245   return;
 246 }                               /* s_ifeqs() */
 247
 248 int
 249 ignore_input ()
 250 {
 251   char *s;
 252
 253   s = input_line_pointer;
 254
 255   if (flag_mri
 256 #ifdef NO_PSEUDO_DOT
 257       || 1
 258 #endif
 259       )
 260     {
 261       if (s[-1] != '.')
 262         --s;
 263     }
 264   else
 265     {
 266       if (s[-1] != '.')
 267         return (current_cframe != NULL) && (current_cframe->ignoring);
 268     }
 269
 270   /* We cannot ignore certain pseudo ops.  */
 271   if ((s[0] == 'i'
 272        && (!strncmp (s, "if", 2)
 273            || !strncmp (s, "ifdef", 5)
 274            || !strncmp (s, "ifndef", 6)))
 275       || (s[0] == 'e'
 276           && (!strncmp (s, "else", 4)
 277               || !strncmp (s, "endif", 5)
 278               || !strncmp (s, "endc", 4))))
 279     return 0;
 280
 281   return (current_cframe != NULL) && (current_cframe->ignoring);
 282 }                               /* ignore_input() */
 283
 284 static void
 285 initialize_cframe (cframe)
 286      struct conditional_frame *cframe;
 287 {
 288   memset (cframe, 0, sizeof (*cframe));
 289   as_where (&cframe->if_file_line.file,
 290             &cframe->if_file_line.line);
 291   cframe->previous_cframe = current_cframe;
 292   cframe->dead_tree = current_cframe != NULL && current_cframe->ignoring;
 293
 294   return;
 295 }                               /* initialize_cframe() */
 296
 297 /*
 298  * Local Variables:
 299  * fill-column: 131
 300  * comment-column: 0
 301  * End:
 302  */
 303
 304 /* end of cond.c */