gas/expr.h

   1 /* expr.h -> header file for expr.c
   2    Copyright (C) 1987, 92-98, 1999 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   /* X_op_symbol [ X_add_symbol ] */
 106   O_index,
 107   /* machine dependent operators */
 108   O_md1,  O_md2,  O_md3,  O_md4,  O_md5,  O_md6,  O_md7,  O_md8,
 109   O_md9,  O_md10, O_md11, O_md12, O_md13, O_md14, O_md15, O_md16,
 110   /* this must be the largest value */
 111   O_max
 112 } operatorT;
 113
 114 typedef struct expressionS
 115 {
 116   /* The main symbol.  */
 117   symbolS *X_add_symbol;
 118   /* The second symbol, if needed.  */
 119   symbolS *X_op_symbol;
 120   /* A number to add.  */
 121   offsetT X_add_number;
 122
 123   /* The type of the expression.  We can't assume that an arbitrary
 124      compiler can handle a bitfield of enum type.  FIXME: We could
 125      check this using autoconf.  */
 126 #ifdef __GNUC__
 127   operatorT X_op : 8;
 128 #else
 129   unsigned char X_op;
 130 #endif
 131
 132   /* Non-zero if X_add_number should be regarded as unsigned.  This is
 133      only valid for O_constant expressions.  It is only used when an
 134      O_constant must be extended into a bignum (i.e., it is not used
 135      when performing arithmetic on these values).
 136      FIXME: This field is not set very reliably.  */
 137   unsigned int X_unsigned : 1;
 138
 139   /* 7 additional bits can be defined if needed.  */
 140
 141   /* Machine dependent field */
 142   unsigned short X_md;
 143 } expressionS;
 144
 145 /* "result" should be type (expressionS *). */
 146 #define expression(result) expr (0, result)
 147
 148 /* If an expression is O_big, look here for its value. These common
 149    data may be clobbered whenever expr() is called. */
 150 /* Flonums returned here.  Big enough to hold most precise flonum. */
 151 extern FLONUM_TYPE generic_floating_point_number;
 152 /* Bignums returned here. */
 153 extern LITTLENUM_TYPE generic_bignum[];
 154 /* Number of littlenums in above. */
 155 #define SIZE_OF_LARGE_NUMBER (20)
 156
 157 typedef char operator_rankT;
 158
 159 extern char get_symbol_end PARAMS ((void));
 160 extern void expr_begin PARAMS ((void));
 161 extern void expr_set_precedence PARAMS ((void));
 162 extern segT expr PARAMS ((int rank, expressionS * resultP));
 163 extern unsigned int get_single_number PARAMS ((void));
 164 extern symbolS *make_expr_symbol PARAMS ((expressionS * expressionP));
 165 extern int expr_symbol_where
 166   PARAMS ((symbolS *, char **, unsigned int *));
 167
 168 extern symbolS *expr_build_uconstant PARAMS ((offsetT));
 169 extern symbolS *expr_build_unary PARAMS ((operatorT, symbolS *));
 170 extern symbolS *expr_build_binary PARAMS ((operatorT, symbolS *, symbolS *));
 171 extern symbolS *expr_build_dot PARAMS ((void));
 172
 173 /* end of expr.h */