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+/* expr.h -> header file for expr.c
+   Copyright (C) 1987, 92-97, 1998 Free Software Foundation, Inc.
+
+   This file is part of GAS, the GNU Assembler.
+
+   GAS is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   GAS is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with GAS; see the file COPYING.  If not, write to the Free
+   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+   02111-1307, USA.  */
+
+/*
+ * By popular demand, we define a struct to represent an expression.
+ * This will no doubt mutate as expressions become baroque.
+ *
+ * Currently, we support expressions like "foo OP bar + 42".  In other
+ * words we permit a (possibly undefined) symbol, a (possibly
+ * undefined) symbol and the operation used to combine the symbols,
+ * and an (absolute) augend.  RMS says this is so we can have 1-pass
+ * assembly for any compiler emissions, and a 'case' statement might
+ * emit 'undefined1 - undefined2'.
+ *
+ * The type of an expression used to be stored as a segment.  That got
+ * confusing because it overloaded the concept of a segment.  I added
+ * an operator field, instead.
+ */
+
+/* This is the type of an expression.  The operator types are also
+   used while parsing an expression.
+
+   NOTE: This enumeration must match the op_rank array in expr.c.  */
+
+typedef enum
+{
+  /* An illegal expression.  */
+  O_illegal,
+  /* A nonexistent expression.  */
+  O_absent,
+  /* X_add_number (a constant expression).  */
+  O_constant,
+  /* X_add_symbol + X_add_number.  */
+  O_symbol,
+  /* X_add_symbol + X_add_number - the base address of the image.  */
+  O_symbol_rva,
+  /* A register (X_add_number is register number).  */
+  O_register,
+  /* A big value.  If X_add_number is negative or 0, the value is in
+     generic_floating_point_number.  Otherwise the value is in
+     generic_bignum, and X_add_number is the number of LITTLENUMs in
+     the value.  */
+  O_big,
+  /* (- X_add_symbol) + X_add_number.  */
+  O_uminus,
+  /* (~ X_add_symbol) + X_add_number.  */
+  O_bit_not,
+  /* (! X_add_symbol) + X_add_number.  */
+  O_logical_not,
+  /* (X_add_symbol * X_op_symbol) + X_add_number.  */
+  O_multiply,
+  /* (X_add_symbol / X_op_symbol) + X_add_number.  */
+  O_divide,
+  /* X_add_symbol % X_op_symbol) + X_add_number.  */
+  O_modulus,
+  /* X_add_symbol << X_op_symbol) + X_add_number.  */
+  O_left_shift,
+  /* X_add_symbol >> X_op_symbol) + X_add_number.  */
+  O_right_shift,
+  /* X_add_symbol | X_op_symbol) + X_add_number.  */
+  O_bit_inclusive_or,
+  /* X_add_symbol |~ X_op_symbol) + X_add_number.  */
+  O_bit_or_not,
+  /* X_add_symbol ^ X_op_symbol) + X_add_number.  */
+  O_bit_exclusive_or,
+  /* X_add_symbol & X_op_symbol) + X_add_number.  */
+  O_bit_and,
+  /* X_add_symbol + X_op_symbol) + X_add_number.  */
+  O_add,
+  /* X_add_symbol - X_op_symbol) + X_add_number.  */
+  O_subtract,
+  /* (X_add_symbol == X_op_symbol) + X_add_number.  */
+  O_eq,
+  /* (X_add_symbol != X_op_symbol) + X_add_number.  */
+  O_ne,
+  /* (X_add_symbol < X_op_symbol) + X_add_number.  */
+  O_lt,
+  /* (X_add_symbol <= X_op_symbol) + X_add_number.  */
+  O_le,
+  /* (X_add_symbol >= X_op_symbol) + X_add_number.  */
+  O_ge,
+  /* (X_add_symbol > X_op_symbol) + X_add_number.  */
+  O_gt,
+  /* (X_add_symbol && X_op_symbol) + X_add_number.  */
+  O_logical_and,
+  /* (X_add_symbol || X_op_symbol) + X_add_number.  */
+  O_logical_or,
+  /* this must be the largest value */
+  O_max
+} operatorT;
+
+typedef struct expressionS
+{
+  /* The main symbol.  */
+  struct symbol *X_add_symbol;
+  /* The second symbol, if needed.  */
+  struct symbol *X_op_symbol;
+  /* A number to add.  */
+  offsetT X_add_number;
+  /* The type of the expression.  We can't assume that an arbitrary
+     compiler can handle a bitfield of enum type.  FIXME: We could
+     check this using autoconf.  */
+#ifdef __GNUC__
+  operatorT X_op : 5;
+#else
+  unsigned X_op : 5;
+#endif
+  /* Non-zero if X_add_number should be regarded as unsigned.  This is
+     only valid for O_constant expressions.  It is only used when an
+     O_constant must be extended into a bignum (i.e., it is not used
+     when performing arithmetic on these values).
+     FIXME: This field is not set very reliably.  */
+  unsigned int X_unsigned : 1;
+} expressionS;
+
+/* "result" should be type (expressionS *). */
+#define expression(result) expr (0, result)
+
+/* If an expression is O_big, look here for its value. These common
+   data may be clobbered whenever expr() is called. */
+/* Flonums returned here.  Big enough to hold most precise flonum. */
+extern FLONUM_TYPE generic_floating_point_number;
+/* Bignums returned here. */
+extern LITTLENUM_TYPE generic_bignum[];
+/* Number of littlenums in above. */
+#define SIZE_OF_LARGE_NUMBER (20)
+
+typedef char operator_rankT;
+
+extern char get_symbol_end PARAMS ((void));
+extern void expr_begin PARAMS ((void));
+extern void expr_set_precedence PARAMS ((void));
+extern segT expr PARAMS ((int rank, expressionS * resultP));
+extern unsigned int get_single_number PARAMS ((void));
+extern struct symbol *make_expr_symbol PARAMS ((expressionS * expressionP));
+extern int expr_symbol_where
+  PARAMS ((struct symbol *, char **, unsigned int *));
+
+extern struct symbol * expr_build_uconstant PARAMS ((offsetT));
+extern struct symbol * expr_build_unary PARAMS ((operatorT, struct symbol *));
+extern struct symbol * expr_build_binary
+  PARAMS ((operatorT, struct symbol *, struct symbol *));
+extern struct symbol * expr_build_dot PARAMS ((void));
+
+/* end of expr.h */