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  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.   /* This is used to implement "word size + 1 bit" arithmetic, so that e.g.
  140.      expressions used with .sleb128 directives can use the full range available
  141.      for an unsigned word, but can also properly represent all values of a
  142.      signed word.  */
  143.   unsigned int X_extrabit : 1;
  144.  
  145.   /* 7 additional bits can be defined if needed.  */
  146.  
  147.   /* Machine dependent field */
  148.   unsigned short X_md;
  149. } expressionS;
  150.  
  151. enum expr_mode
  152. {
  153.   expr_evaluate,
  154.   expr_normal,
  155.   expr_defer
  156. };
  157.  
  158. /* "result" should be type (expressionS *).  */
  159. #define expression(result) expr (0, result, expr_normal)
  160. #define expression_and_evaluate(result) expr (0, result, expr_evaluate)
  161. #define deferred_expression(result) expr (0, result, expr_defer)
  162.  
  163. /* If an expression is O_big, look here for its value. These common
  164.    data may be clobbered whenever expr() is called.  */
  165. /* Flonums returned here.  Big enough to hold most precise flonum.  */
  166. extern FLONUM_TYPE generic_floating_point_number;
  167. /* Bignums returned here.  */
  168. extern LITTLENUM_TYPE generic_bignum[];
  169. /* Number of littlenums in above.  */
  170. #define SIZE_OF_LARGE_NUMBER (20)
  171.  
  172. typedef char operator_rankT;
  173.  
  174. extern char get_symbol_end (void);
  175. extern void expr_begin (void);
  176. extern void expr_set_precedence (void);
  177. extern void expr_set_rank (operatorT, operator_rankT);
  178. extern void add_to_result (expressionS *, offsetT, int);
  179. extern void subtract_from_result (expressionS *, offsetT, int);
  180. extern segT expr (int, expressionS *, enum expr_mode);
  181. extern unsigned int get_single_number (void);
  182. extern symbolS *make_expr_symbol (expressionS * expressionP);
  183. extern int expr_symbol_where (symbolS *, char **, unsigned int *);
  184. extern void current_location (expressionS *);
  185.  
  186. extern symbolS *expr_build_uconstant (offsetT);
  187. extern symbolS *expr_build_dot (void);
  188.  
  189. int resolve_expression (expressionS *);
  190.