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  1. /* expr.h -> header file for expr.c
  2.    Copyright (C) 1987-2015 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 3, 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, 51 Franklin Street - Fifth Floor, Boston, MA
  19.    02110-1301, 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.   /* An illegal expression.  */
  44.   O_illegal,
  45.   /* A nonexistent expression.  */
  46.   O_absent,
  47.   /* X_add_number (a constant expression).  */
  48.   O_constant,
  49.   /* X_add_symbol + X_add_number.  */
  50.   O_symbol,
  51.   /* X_add_symbol + X_add_number - the base address of the image.  */
  52.   O_symbol_rva,
  53.   /* A register (X_add_number is register number).  */
  54.   O_register,
  55.   /* A big value.  If X_add_number is negative or 0, the value is in
  56.      generic_floating_point_number.  Otherwise the value is in
  57.      generic_bignum, and X_add_number is the number of LITTLENUMs in
  58.      the value.  */
  59.   O_big,
  60.   /* (- X_add_symbol) + X_add_number.  */
  61.   O_uminus,
  62.   /* (~ X_add_symbol) + X_add_number.  */
  63.   O_bit_not,
  64.   /* (! X_add_symbol) + X_add_number.  */
  65.   O_logical_not,
  66.   /* (X_add_symbol * X_op_symbol) + X_add_number.  */
  67.   O_multiply,
  68.   /* (X_add_symbol / X_op_symbol) + X_add_number.  */
  69.   O_divide,
  70.   /* (X_add_symbol % X_op_symbol) + X_add_number.  */
  71.   O_modulus,
  72.   /* (X_add_symbol << X_op_symbol) + X_add_number.  */
  73.   O_left_shift,
  74.   /* (X_add_symbol >> X_op_symbol) + X_add_number.  */
  75.   O_right_shift,
  76.   /* (X_add_symbol | X_op_symbol) + X_add_number.  */
  77.   O_bit_inclusive_or,
  78.   /* (X_add_symbol |~ X_op_symbol) + X_add_number.  */
  79.   O_bit_or_not,
  80.   /* (X_add_symbol ^ X_op_symbol) + X_add_number.  */
  81.   O_bit_exclusive_or,
  82.   /* (X_add_symbol & X_op_symbol) + X_add_number.  */
  83.   O_bit_and,
  84.   /* (X_add_symbol + X_op_symbol) + X_add_number.  */
  85.   O_add,
  86.   /* (X_add_symbol - X_op_symbol) + X_add_number.  */
  87.   O_subtract,
  88.   /* (X_add_symbol == X_op_symbol) + X_add_number.  */
  89.   O_eq,
  90.   /* (X_add_symbol != X_op_symbol) + X_add_number.  */
  91.   O_ne,
  92.   /* (X_add_symbol < X_op_symbol) + X_add_number.  */
  93.   O_lt,
  94.   /* (X_add_symbol <= X_op_symbol) + X_add_number.  */
  95.   O_le,
  96.   /* (X_add_symbol >= X_op_symbol) + X_add_number.  */
  97.   O_ge,
  98.   /* (X_add_symbol > X_op_symbol) + X_add_number.  */
  99.   O_gt,
  100.   /* (X_add_symbol && X_op_symbol) + X_add_number.  */
  101.   O_logical_and,
  102.   /* (X_add_symbol || X_op_symbol) + X_add_number.  */
  103.   O_logical_or,
  104.   /* X_op_symbol [ X_add_symbol ] */
  105.   O_index,
  106.   /* machine dependent operators */
  107.   O_md1,  O_md2,  O_md3,  O_md4,  O_md5,  O_md6,  O_md7,  O_md8,
  108.   O_md9,  O_md10, O_md11, O_md12, O_md13, O_md14, O_md15, O_md16,
  109.   O_md17, O_md18, O_md19, O_md20, O_md21, O_md22, O_md23, O_md24,
  110.   O_md25, O_md26, O_md27, O_md28, O_md29, O_md30, O_md31, O_md32,
  111.   /* this must be the largest value */
  112.   O_max
  113. } operatorT;
  114.  
  115. typedef struct expressionS {
  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.   /* This is used to implement "word size + 1 bit" arithmetic, so that e.g.
  139.      expressions used with .sleb128 directives can use the full range available
  140.      for an unsigned word, but can also properly represent all values of a
  141.      signed word.  */
  142.   unsigned int X_extrabit : 1;
  143.  
  144.   /* 7 additional bits can be defined if needed.  */
  145.  
  146.   /* Machine dependent field */
  147.   unsigned short X_md;
  148. } expressionS;
  149.  
  150. enum expr_mode
  151. {
  152.   expr_evaluate,
  153.   expr_normal,
  154.   expr_defer
  155. };
  156.  
  157. /* "result" should be type (expressionS *).  */
  158. #define expression(result) expr (0, result, expr_normal)
  159. #define expression_and_evaluate(result) expr (0, result, expr_evaluate)
  160. #define deferred_expression(result) expr (0, result, expr_defer)
  161.  
  162. /* If an expression is O_big, look here for its value. These common
  163.    data may be clobbered whenever expr() is called.  */
  164. /* Flonums returned here.  Big enough to hold most precise flonum.  */
  165. extern FLONUM_TYPE generic_floating_point_number;
  166. /* Bignums returned here.  */
  167. extern LITTLENUM_TYPE generic_bignum[];
  168. /* Number of littlenums in above.  */
  169. #define SIZE_OF_LARGE_NUMBER (20)
  170.  
  171. typedef char operator_rankT;
  172.  
  173. extern char get_symbol_name (char **);
  174. extern char restore_line_pointer (char);
  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.