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/* DWARF 2 Expression Evaluator.

   Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008

   Free Software Foundation, Inc.

   Contributed by Daniel Berlin <dan@dberlin.org>.

   This file is part of GDB.

   This program 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 3 of the License, or

   (at your option) any later version.

   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */

#if !defined (DWARF2EXPR_H)

#define DWARF2EXPR_H

/* The expression evaluator works with a dwarf_expr_context, describing

   its current state and its callbacks.  */

struct dwarf_expr_context

{

  /* The stack of values, allocated with xmalloc.  */

  CORE_ADDR *stack;

  /* The number of values currently pushed on the stack, and the

     number of elements allocated to the stack.  */

  int stack_len, stack_allocated;

  /* An opaque argument provided by the caller, which will be passed

     to all of the callback functions.  */

  void *baton;

  /* Return the value of register number REGNUM.  */

  CORE_ADDR (*read_reg) (void *baton, int regnum);

  /* Read LENGTH bytes at ADDR into BUF.  */

  void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length);

  /* Return the location expression for the frame base attribute, in

     START and LENGTH.  The result must be live until the current

     expression evaluation is complete.  */

  void (*get_frame_base) (void *baton, gdb_byte **start, size_t *length);

  /* Return the thread-local storage address for

     DW_OP_GNU_push_tls_address.  */

  CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset);

#if 0

  /* Not yet implemented.  */

  /* Return the location expression for the dwarf expression

     subroutine in the die at OFFSET in the current compilation unit.

     The result must be live until the current expression evaluation

     is complete.  */

  unsigned char *(*get_subr) (void *baton, off_t offset, size_t *length);

  /* Return the `object address' for DW_OP_push_object_address.  */

  CORE_ADDR (*get_object_address) (void *baton);

#endif

  /* The current depth of dwarf expression recursion, via DW_OP_call*,

     DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum

     depth we'll tolerate before raising an error.  */

  int recursion_depth, max_recursion_depth;

  /* Non-zero if the result is in a register.  The register number

     will be on the expression stack.  */

  int in_reg;

  /* Initialization status of variable: Non-zero if variable has been

     initialized; zero otherwise.  */

  int initialized;

  /* An array of pieces.  PIECES points to its first element;

     NUM_PIECES is its length.

     Each time DW_OP_piece is executed, we add a new element to the

     end of this array, recording the current top of the stack, the

     current in_reg flag, and the size given as the operand to

     DW_OP_piece.  We then pop the top value from the stack, clear the

     in_reg flag, and resume evaluation.

     The Dwarf spec doesn't say whether DW_OP_piece pops the top value

     from the stack.  We do, ensuring that clients of this interface

     expecting to see a value left on the top of the stack (say, code

     evaluating frame base expressions or CFA's specified with

     DW_CFA_def_cfa_expression) will get an error if the expression

     actually marks all the values it computes as pieces.

     If an expression never uses DW_OP_piece, num_pieces will be zero.

     (It would be nice to present these cases as expressions yielding

     a single piece, with in_reg clear, so that callers need not

     distinguish between the no-DW_OP_piece and one-DW_OP_piece cases.

     But expressions with no DW_OP_piece operations have no value to

     place in a piece's 'size' field; the size comes from the

     surrounding data.  So the two cases need to be handled

     separately.)  */

  int num_pieces;

  struct dwarf_expr_piece *pieces;

};

/* A piece of an object, as recorded by DW_OP_piece.  */

struct dwarf_expr_piece

{

  /* If IN_REG is zero, then the piece is in memory, and VALUE is its address.

     If IN_REG is non-zero, then the piece is in a register, and VALUE

     is the register number.  */

  int in_reg;

  /* This piece's address or register number.  */

  CORE_ADDR value;

  /* The length of the piece, in bytes.  */

  ULONGEST size;

};

struct dwarf_expr_context *new_dwarf_expr_context (void);

void free_dwarf_expr_context (struct dwarf_expr_context *ctx);

void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value);

void dwarf_expr_pop (struct dwarf_expr_context *ctx);

void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr,

                      size_t len);

CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n);

gdb_byte *read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r);

gdb_byte *read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r);

CORE_ADDR dwarf2_read_address (gdb_byte *buf, gdb_byte *buf_end,

                               int *bytes_read);

#endif /* dwarf2expr.h */