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       ignore_rest_of_line ();
  65     }
  66   else
  67     {
  68       char c;
  69
  70       c = get_symbol_end ();
  71       symbolP = symbol_find (name);
  72       *input_line_pointer = c;
  73
  74       initialize_cframe (&cframe);
  75       cframe.ignoring = cframe.dead_tree || !((symbolP != 0) ^ arg);
  76       current_cframe = ((struct conditional_frame *)
  77                         obstack_copy (&cond_obstack, &cframe,
  78                                       sizeof (cframe)));
  79       demand_empty_rest_of_line ();
  80     }                           /* if a valid identifyer name */
  81 }                               /* s_ifdef() */
  82
  83 void
  84 s_if (arg)
  85      int arg;
  86 {
  87   expressionS operand;
  88   struct conditional_frame cframe;
  89   int t;
  90
  91   SKIP_WHITESPACE ();           /* Leading whitespace is part of operand. */
  92
  93   if (current_cframe != NULL && current_cframe->ignoring)
  94     {
  95       operand.X_add_number = 0;
  96       while (! is_end_of_line[(unsigned char) *input_line_pointer])
  97         ++input_line_pointer;
  98     }
  99   else
 100     {
 101       expression (&operand);
 102       if (operand.X_op != O_constant)
 103         as_bad ("non-constant expression in \".if\" statement");
 104     }
 105
 106   switch ((operatorT) arg)
 107     {
 108     case O_eq: t = operand.X_add_number == 0; break;
 109     case O_ne: t = operand.X_add_number != 0; break;
 110     case O_lt: t = operand.X_add_number < 0; break;
 111     case O_le: t = operand.X_add_number <= 0; break;
 112     case O_ge: t = operand.X_add_number >= 0; break;
 113     case O_gt: t = operand.X_add_number > 0; break;
 114     default:
 115       abort ();
 116     }
 117
 118   /* If the above error is signaled, this will dispatch
 119      using an undefined result.  No big deal.  */
 120   initialize_cframe (&cframe);
 121   cframe.ignoring = cframe.dead_tree || ! t;
 122   current_cframe = ((struct conditional_frame *)
 123                     obstack_copy (&cond_obstack, &cframe, sizeof (cframe)));
 124
 125   demand_empty_rest_of_line ();
 126 }                               /* s_if() */
 127
 128 /* Get a string for the MRI IFC or IFNC pseudo-ops.  */
 129
 130 static char *
 131 get_mri_string (terminator, len)
 132      int terminator;
 133      int *len;
 134 {
 135   char *ret;
 136   char *s;
 137
 138   SKIP_WHITESPACE ();
 139   s = ret = input_line_pointer;
 140   if (*input_line_pointer == '\'')
 141     {
 142       ++s;
 143       ++input_line_pointer;
 144       while (! is_end_of_line[(unsigned char) *input_line_pointer])
 145         {
 146           *s++ = *input_line_pointer++;
 147           if (s[-1] == '\'')
 148             {
 149               if (*input_line_pointer != '\'')
 150                 break;
 151               ++input_line_pointer;
 152             }
 153         }
 154       SKIP_WHITESPACE ();
 155     }
 156   else
 157     {
 158       while (*input_line_pointer != terminator
 159              && ! is_end_of_line[(unsigned char) *input_line_pointer])
 160         ++input_line_pointer;
 161       s = input_line_pointer;
 162       while (s > ret && (s[-1] == ' ' || s[-1] == '\t'))
 163         --s;
 164     }
 165
 166   *len = s - ret;
 167   return ret;
 168 }
 169
 170 /* The MRI IFC and IFNC pseudo-ops.  */
 171
 172 void
 173 s_ifc (arg)
 174      int arg;
 175 {
 176   char *s1, *s2;
 177   int len1, len2;
 178   int res;
 179   struct conditional_frame cframe;
 180
 181   s1 = get_mri_string (',', &len1);
 182
 183   if (*input_line_pointer != ',')
 184     as_bad ("bad format for ifc or ifnc");
 185   else
 186     ++input_line_pointer;
 187
 188   s2 = get_mri_string (';', &len2);
 189
 190   res = len1 == len2 && strncmp (s1, s2, len1) == 0;
 191
 192   initialize_cframe (&cframe);
 193   cframe.ignoring = cframe.dead_tree || ! (res ^ arg);
 194   current_cframe = ((struct conditional_frame *)
 195                     obstack_copy (&cond_obstack, &cframe, sizeof (cframe)));
 196 }
 197
 198 void
 199 s_endif (arg)
 200      int arg;
 201 {
 202   struct conditional_frame *hold;
 203
 204   if (current_cframe == NULL)
 205     {
 206       as_bad ("\".endif\" without \".if\"");
 207     }
 208   else
 209     {
 210       hold = current_cframe;
 211       current_cframe = current_cframe->previous_cframe;
 212       obstack_free (&cond_obstack, hold);
 213     }                           /* if one pop too many */
 214
 215   return;
 216 }                               /* s_endif() */
 217
 218 void
 219 s_else (arg)
 220      int arg;
 221 {
 222   if (current_cframe == NULL)
 223     {
 224       as_bad (".else without matching .if - ignored");
 225
 226     }
 227   else if (current_cframe->else_seen)
 228     {
 229       as_bad ("duplicate \"else\" - ignored");
 230       as_bad_where (current_cframe->else_file_line.file,
 231                     current_cframe->else_file_line.line,
 232                     "here is the previous \"else\"");
 233       as_bad_where (current_cframe->if_file_line.file,
 234                     current_cframe->if_file_line.line,
 235                     "here is the previous \"if\"");
 236     }
 237   else
 238     {
 239       as_where (&current_cframe->else_file_line.file,
 240                 &current_cframe->else_file_line.line);
 241
 242       if (!current_cframe->dead_tree)
 243         {
 244           current_cframe->ignoring = !current_cframe->ignoring;
 245         }                       /* if not a dead tree */
 246
 247       current_cframe->else_seen = 1;
 248     }                           /* if error else do it */
 249
 250   return;
 251 }                               /* s_else() */
 252
 253 void
 254 s_ifeqs (arg)
 255      int arg;
 256 {
 257   as_bad ("ifeqs not implemented.");
 258
 259   return;
 260 }                               /* s_ifeqs() */
 261
 262 int
 263 ignore_input ()
 264 {
 265   char *s;
 266
 267   s = input_line_pointer;
 268
 269   if (flag_mri
 270 #ifdef NO_PSEUDO_DOT
 271       || 1
 272 #endif
 273       )
 274     {
 275       if (s[-1] != '.')
 276         --s;
 277     }
 278   else
 279     {
 280       if (s[-1] != '.')
 281         return (current_cframe != NULL) && (current_cframe->ignoring);
 282     }
 283
 284   /* We cannot ignore certain pseudo ops.  */
 285   if (((s[0] == 'i'
 286         || s[0] == 'I')
 287        && (!strncasecmp (s, "if", 2)
 288            || !strncasecmp (s, "ifdef", 5)
 289            || !strncasecmp (s, "ifndef", 6)))
 290       || ((s[0] == 'e'
 291            || s[0] == 'E')
 292           && (!strncasecmp (s, "else", 4)
 293               || !strncasecmp (s, "endif", 5)
 294               || !strncasecmp (s, "endc", 4))))
 295     return 0;
 296
 297   return (current_cframe != NULL) && (current_cframe->ignoring);
 298 }                               /* ignore_input() */
 299
 300 static void
 301 initialize_cframe (cframe)
 302      struct conditional_frame *cframe;
 303 {
 304   memset (cframe, 0, sizeof (*cframe));
 305   as_where (&cframe->if_file_line.file,
 306             &cframe->if_file_line.line);
 307   cframe->previous_cframe = current_cframe;
 308   cframe->dead_tree = current_cframe != NULL && current_cframe->ignoring;
 309
 310   return;
 311 }                               /* initialize_cframe() */
 312
 313 /*
 314  * Local Variables:
 315  * fill-column: 131
 316  * comment-column: 0
 317  * End:
 318  */
 319
 320 /* end of cond.c */