gas/expr.h

   1 /* expr.h -> header file for expr.c
   2    Copyright 1987, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
   3    2002, 2003, 2005, 2007, 2009 Free Software Foundation, Inc.
   4
   5    This file is part of GAS, the GNU Assembler.
   6
   7    GAS is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    GAS is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GAS; see the file COPYING.  If not, write to the Free
  19    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  20    02110-1301, USA.  */
  21
  22 /*
  23  * By popular demand, we define a struct to represent an expression.
  24  * This will no doubt mutate as expressions become baroque.
  25  *
  26  * Currently, we support expressions like "foo OP bar + 42".  In other
  27  * words we permit a (possibly undefined) symbol, a (possibly
  28  * undefined) symbol and the operation used to combine the symbols,
  29  * and an (absolute) augend.  RMS says this is so we can have 1-pass
  30  * assembly for any compiler emissions, and a 'case' statement might
  31  * emit 'undefined1 - undefined2'.
  32  *
  33  * The type of an expression used to be stored as a segment.  That got
  34  * confusing because it overloaded the concept of a segment.  I added
  35  * an operator field, instead.
  36  */
  37
  38 /* This is the type of an expression.  The operator types are also
  39    used while parsing an expression.
  40
  41    NOTE: This enumeration must match the op_rank array in expr.c.  */
  42
  43 typedef enum {
  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   O_md17, O_md18, O_md19, O_md20, O_md21, O_md22, O_md23, O_md24,
 111   O_md25, O_md26, O_md27, O_md28, O_md29, O_md30, O_md31, O_md32,
 112   /* this must be the largest value */
 113   O_max
 114 } operatorT;
 115
 116 typedef struct expressionS {
 117   /* The main symbol.  */
 118   symbolS *X_add_symbol;
 119   /* The second symbol, if needed.  */
 120   symbolS *X_op_symbol;
 121   /* A number to add.  */
 122   offsetT X_add_number;
 123
 124   /* The type of the expression.  We can't assume that an arbitrary
 125      compiler can handle a bitfield of enum type.  FIXME: We could
 126      check this using autoconf.  */
 127 #ifdef __GNUC__
 128   operatorT X_op : 8;
 129 #else
 130   unsigned char X_op;
 131 #endif
 132
 133   /* Non-zero if X_add_number should be regarded as unsigned.  This is
 134      only valid for O_constant expressions.  It is only used when an
 135      O_constant must be extended into a bignum (i.e., it is not used
 136      when performing arithmetic on these values).
 137      FIXME: This field is not set very reliably.  */
 138   unsigned int X_unsigned : 1;
 139
 140   /* 7 additional bits can be defined if needed.  */
 141
 142   /* Machine dependent field */
 143   unsigned short X_md;
 144 } expressionS;
 145
 146 enum expr_mode
 147 {
 148   expr_evaluate,
 149   expr_normal,
 150   expr_defer
 151 };
 152
 153 /* "result" should be type (expressionS *).  */
 154 #define expression(result) expr (0, result, expr_normal)
 155 #define expression_and_evaluate(result) expr (0, result, expr_evaluate)
 156 #define deferred_expression(result) expr (0, result, expr_defer)
 157
 158 /* If an expression is O_big, look here for its value. These common
 159    data may be clobbered whenever expr() is called.  */
 160 /* Flonums returned here.  Big enough to hold most precise flonum.  */
 161 extern FLONUM_TYPE generic_floating_point_number;
 162 /* Bignums returned here.  */
 163 extern LITTLENUM_TYPE generic_bignum[];
 164 /* Number of littlenums in above.  */
 165 #define SIZE_OF_LARGE_NUMBER (20)
 166
 167 typedef char operator_rankT;
 168
 169 extern char get_symbol_end (void);
 170 extern void expr_begin (void);
 171 extern void expr_set_precedence (void);
 172 extern void expr_set_rank (operatorT, operator_rankT);
 173 extern segT expr (int, expressionS *, enum expr_mode);
 174 extern unsigned int get_single_number (void);
 175 extern symbolS *make_expr_symbol (expressionS * expressionP);
 176 extern int expr_symbol_where (symbolS *, char **, unsigned int *);
 177 extern void current_location (expressionS *);
 178
 179 extern symbolS *expr_build_uconstant (offsetT);
 180 extern symbolS *expr_build_dot (void);
 181
 182 int resolve_expression (expressionS *);