gas/cond.c

   1 /* cond.c - conditional assembly pseudo-ops, and .include
   2    Copyright (C) 1990, 1991 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, 675 Mass Ave, Cambridge, MA 02139, 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         char *logical_file;
  29         int logical_line;
  30         char *physical_file;
  31         int physical_line;
  32 }; /* file_line */
  33
  34 /* This is what we push and pop. */
  35 struct conditional_frame {
  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 #ifdef __STDC__
  45
  46 static void get_file_line(struct file_line *into);
  47 static void initialize_cframe(struct conditional_frame *cframe);
  48 static void set_file_line(struct file_line *from);
  49
  50 #else
  51
  52 static void get_file_line();
  53 static void initialize_cframe();
  54 static void set_file_line();
  55
  56 #endif
  57
  58 static struct conditional_frame *current_cframe = NULL;
  59
  60 void s_ifdef(arg)
  61 int arg;
  62 {
  63         register char *name; /* points to name of symbol */
  64         register struct symbol *symbolP; /* Points to symbol */
  65         struct conditional_frame cframe;
  66
  67         SKIP_WHITESPACE();              /* Leading whitespace is part of operand. */
  68         name = input_line_pointer;
  69
  70         if (!is_name_beginner(*name)) {
  71                 as_bad("invalid identifier for \".ifdef\"");
  72                 obstack_1grow(&cond_obstack, 0);
  73         } else {
  74                 get_symbol_end();
  75                 ++input_line_pointer;
  76                 symbolP = symbol_find(name);
  77
  78                 initialize_cframe(&cframe);
  79                 cframe.ignoring = cframe.dead_tree && !((symbolP != 0) ^ arg);
  80                 current_cframe = (struct conditional_frame *) obstack_copy(&cond_obstack, &cframe, sizeof(cframe));
  81         } /* if a valid identifyer name */
  82
  83         return;
  84 } /* s_ifdef() */
  85
  86 void s_if(arg)
  87 int arg;
  88 {
  89         expressionS operand;
  90         struct conditional_frame cframe;
  91
  92         SKIP_WHITESPACE(); /* Leading whitespace is part of operand. */
  93         expr(0, &operand);
  94
  95         if (operand.X_add_symbol != NULL
  96             || operand.X_subtract_symbol != NULL) {
  97                 as_bad("non-constant expression in \".if\" statement");
  98         } /* bad condition */
  99
 100         /* If the above error is signaled, this will dispatch
 101            using an undefined result.  No big deal.  */
 102         initialize_cframe(&cframe);
 103         cframe.ignoring = cframe.dead_tree || !((operand.X_add_number != 0) ^ arg);
 104         current_cframe = (struct conditional_frame *) obstack_copy(&cond_obstack, &cframe, sizeof(cframe));
 105         return;
 106 } /* s_if() */
 107
 108 void s_endif(arg)
 109 int arg;
 110 {
 111         struct conditional_frame *hold;
 112
 113         if (current_cframe == NULL) {
 114                 as_bad("\".endif\" without \".if\"");
 115         } else {
 116                 hold = current_cframe;
 117                 current_cframe = current_cframe->previous_cframe;
 118                 obstack_free(&cond_obstack, hold);
 119         } /* if one pop too many */
 120
 121         return;
 122 } /* s_endif() */
 123
 124 void s_else(arg)
 125 int arg;
 126 {
 127         if (current_cframe == NULL) {
 128                 as_bad(".else without matching .if - ignored");
 129
 130         } else if (current_cframe->else_seen) {
 131                 struct file_line hold;
 132                 as_bad("duplicate \"else\" - ignored");
 133
 134                 get_file_line(&hold);
 135                 set_file_line(&current_cframe->else_file_line);
 136                 as_bad("here is the previous \"else\".");
 137                 set_file_line(&current_cframe->if_file_line);
 138                 as_bad("here is the matching \".if\".");
 139                 set_file_line(&hold);
 140
 141         } else {
 142                 get_file_line(&current_cframe->else_file_line);
 143
 144                 if (!current_cframe->dead_tree) {
 145                         current_cframe->ignoring = !current_cframe->ignoring;
 146                 } /* if not a dead tree */
 147
 148                 current_cframe->else_seen = 1;
 149         } /* if error else do it */
 150
 151         return;
 152 } /* s_else() */
 153
 154 void s_ifeqs(arg)
 155 int arg;
 156 {
 157         as_bad("ifeqs not implemented.");
 158
 159         return;
 160 } /* s_ifeqs() */
 161
 162 void s_end(arg)
 163 int arg;
 164 {
 165         return;
 166 } /* s_end() */
 167
 168 int ignore_input() {
 169         char *ptr = obstack_next_free (&cond_obstack);
 170
 171         /* We cannot ignore certain pseudo ops.  */
 172         if (input_line_pointer[-1] == '.'
 173             && ((input_line_pointer[0] == 'i'
 174                  && (!strncmp (input_line_pointer, "if", 2)
 175                      || !strncmp (input_line_pointer, "ifdef", 5)
 176                      || !strncmp (input_line_pointer, "ifndef", 6)))
 177                 || (input_line_pointer[0] == 'e'
 178                     && (!strncmp (input_line_pointer, "else", 4)
 179                         || !strncmp (input_line_pointer, "endif", 5))))) {
 180                 return 0;
 181         }
 182
 183         return((current_cframe != NULL) && (current_cframe->ignoring));
 184 } /* ignore_input() */
 185
 186 static void initialize_cframe(cframe)
 187 struct conditional_frame *cframe;
 188 {
 189         memset(cframe, 0, sizeof(*cframe));
 190         get_file_line(&(cframe->if_file_line));
 191         cframe->previous_cframe = current_cframe;
 192         cframe->dead_tree = current_cframe != NULL && current_cframe->ignoring;
 193
 194         return;
 195 } /* initialize_cframe() */
 196
 197 static void get_file_line(into)
 198 struct file_line *into;
 199 {
 200         extern char *logical_input_file;
 201         extern char *physical_input_file;
 202         extern int logical_input_line;
 203         extern int physical_input_line;
 204
 205         into->logical_file = logical_input_file;
 206         into->logical_line = logical_input_line;
 207         into->physical_file = physical_input_file;
 208         into->physical_line = physical_input_line;
 209
 210         return;
 211 } /* get_file_line() */
 212
 213 static void set_file_line(from)
 214 struct file_line *from;
 215 {
 216         extern char *logical_input_file;
 217         extern char *physical_input_file;
 218         extern int logical_input_line;
 219         extern int physical_input_line;
 220
 221         logical_input_file = from->logical_file;
 222         logical_input_line = from->logical_line;
 223         physical_input_file = from->physical_file;
 224         physical_input_line = from->physical_line;
 225         return;
 226 } /* set_file_line() */
 227
 228 /*
 229  * Local Variables:
 230  * fill-column: 131
 231  * comment-column: 0
 232  * End:
 233  */
 234
 235 /* end of cond.c */