gas/expr.h

   1 /* expr.h -> header file for expr.c
   2    Copyright (C) 1987, 92-97, 1998 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 the Free
  18    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  19    02111-1307, USA.  */
  20
  21 /*
  22  * By popular demand, we define a struct to represent an expression.
  23  * This will no doubt mutate as expressions become baroque.
  24  *
  25  * Currently, we support expressions like "foo OP bar + 42".  In other
  26  * words we permit a (possibly undefined) symbol, a (possibly
  27  * undefined) symbol and the operation used to combine the symbols,
  28  * and an (absolute) augend.  RMS says this is so we can have 1-pass
  29  * assembly for any compiler emissions, and a 'case' statement might
  30  * emit 'undefined1 - undefined2'.
  31  *
  32  * The type of an expression used to be stored as a segment.  That got
  33  * confusing because it overloaded the concept of a segment.  I added
  34  * an operator field, instead.
  35  */
  36
  37 /* This is the type of an expression.  The operator types are also
  38    used while parsing an expression.
  39
  40    NOTE: This enumeration must match the op_rank array in expr.c.  */
  41
  42 typedef enum
  43 {
  44   /* An illegal expression.  */
  45   O_illegal,
  46   /* A nonexistent expression.  */
  47   O_absent,
  48   /* X_add_number (a constant expression).  */
  49   O_constant,
  50   /* X_add_symbol + X_add_number.  */
  51   O_symbol,
  52   /* X_add_symbol + X_add_number - the base address of the image.  */
  53   O_symbol_rva,
  54   /* A register (X_add_number is register number).  */
  55   O_register,
  56   /* A big value.  If X_add_number is negative or 0, the value is in
  57      generic_floating_point_number.  Otherwise the value is in
  58      generic_bignum, and X_add_number is the number of LITTLENUMs in
  59      the value.  */
  60   O_big,
  61   /* (- X_add_symbol) + X_add_number.  */
  62   O_uminus,
  63   /* (~ X_add_symbol) + X_add_number.  */
  64   O_bit_not,
  65   /* (! X_add_symbol) + X_add_number.  */
  66   O_logical_not,
  67   /* (X_add_symbol * X_op_symbol) + X_add_number.  */
  68   O_multiply,
  69   /* (X_add_symbol / X_op_symbol) + X_add_number.  */
  70   O_divide,
  71   /* X_add_symbol % X_op_symbol) + X_add_number.  */
  72   O_modulus,
  73   /* X_add_symbol << X_op_symbol) + X_add_number.  */
  74   O_left_shift,
  75   /* X_add_symbol >> X_op_symbol) + X_add_number.  */
  76   O_right_shift,
  77   /* X_add_symbol | X_op_symbol) + X_add_number.  */
  78   O_bit_inclusive_or,
  79   /* X_add_symbol |~ X_op_symbol) + X_add_number.  */
  80   O_bit_or_not,
  81   /* X_add_symbol ^ X_op_symbol) + X_add_number.  */
  82   O_bit_exclusive_or,
  83   /* X_add_symbol & X_op_symbol) + X_add_number.  */
  84   O_bit_and,
  85   /* X_add_symbol + X_op_symbol) + X_add_number.  */
  86   O_add,
  87   /* X_add_symbol - X_op_symbol) + X_add_number.  */
  88   O_subtract,
  89   /* (X_add_symbol == X_op_symbol) + X_add_number.  */
  90   O_eq,
  91   /* (X_add_symbol != X_op_symbol) + X_add_number.  */
  92   O_ne,
  93   /* (X_add_symbol < X_op_symbol) + X_add_number.  */
  94   O_lt,
  95   /* (X_add_symbol <= X_op_symbol) + X_add_number.  */
  96   O_le,
  97   /* (X_add_symbol >= X_op_symbol) + X_add_number.  */
  98   O_ge,
  99   /* (X_add_symbol > X_op_symbol) + X_add_number.  */
 100   O_gt,
 101   /* (X_add_symbol && X_op_symbol) + X_add_number.  */
 102   O_logical_and,
 103   /* (X_add_symbol || X_op_symbol) + X_add_number.  */
 104   O_logical_or,
 105   /* this must be the largest value */
 106   O_max
 107 } operatorT;
 108
 109 typedef struct expressionS
 110 {
 111   /* The main symbol.  */
 112   struct symbol *X_add_symbol;
 113   /* The second symbol, if needed.  */
 114   struct symbol *X_op_symbol;
 115   /* A number to add.  */
 116   offsetT X_add_number;
 117   /* The type of the expression.  We can't assume that an arbitrary
 118      compiler can handle a bitfield of enum type.  FIXME: We could
 119      check this using autoconf.  */
 120 #ifdef __GNUC__
 121   operatorT X_op : 5;
 122 #else
 123   unsigned X_op : 5;
 124 #endif
 125   /* Non-zero if X_add_number should be regarded as unsigned.  This is
 126      only valid for O_constant expressions.  It is only used when an
 127      O_constant must be extended into a bignum (i.e., it is not used
 128      when performing arithmetic on these values).
 129      FIXME: This field is not set very reliably.  */
 130   unsigned int X_unsigned : 1;
 131 } expressionS;
 132
 133 /* "result" should be type (expressionS *). */
 134 #define expression(result) expr (0, result)
 135
 136 /* If an expression is O_big, look here for its value. These common
 137    data may be clobbered whenever expr() is called. */
 138 /* Flonums returned here.  Big enough to hold most precise flonum. */
 139 extern FLONUM_TYPE generic_floating_point_number;
 140 /* Bignums returned here. */
 141 extern LITTLENUM_TYPE generic_bignum[];
 142 /* Number of littlenums in above. */
 143 #define SIZE_OF_LARGE_NUMBER (20)
 144
 145 typedef char operator_rankT;
 146
 147 extern char get_symbol_end PARAMS ((void));
 148 extern void expr_begin PARAMS ((void));
 149 extern void expr_set_precedence PARAMS ((void));
 150 extern segT expr PARAMS ((int rank, expressionS * resultP));
 151 extern unsigned int get_single_number PARAMS ((void));
 152 extern struct symbol *make_expr_symbol PARAMS ((expressionS * expressionP));
 153 extern int expr_symbol_where
 154   PARAMS ((struct symbol *, char **, unsigned int *));
 155
 156 extern struct symbol * expr_build_uconstant PARAMS ((offsetT));
 157 extern struct symbol * expr_build_unary PARAMS ((operatorT, struct symbol *));
 158 extern struct symbol * expr_build_binary
 159   PARAMS ((operatorT, struct symbol *, struct symbol *));
 160 extern struct symbol * expr_build_dot PARAMS ((void));
 161
 162 /* end of expr.h */