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/* Low level packing and unpacking of values for GDB, the GNU Debugger.

   Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,

   1995, 1996, 1997, 1998, 1999, 2000, 2002.

   Free Software Foundation, Inc.

   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 2 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, write to the Free Software

   Foundation, Inc., 59 Temple Place - Suite 330,

   Boston, MA 02111-1307, USA.  */

#include "defs.h"

#include "gdb_string.h"

#include "symtab.h"

#include "gdbtypes.h"

#include "value.h"

#include "gdbcore.h"

#include "command.h"

#include "gdbcmd.h"

#include "target.h"

#include "language.h"

#include "scm-lang.h"

#include "demangle.h"

#include "doublest.h"

#include "gdb_assert.h"

#include "regcache.h"

/* Prototypes for exported functions. */

void _initialize_values (void);

/* Prototypes for local functions. */

static void show_values (char *, int);

static void show_convenience (char *, int);

/* The value-history records all the values printed

   by print commands during this session.  Each chunk

   records 60 consecutive values.  The first chunk on

   the chain records the most recent values.

   The total number of values is in value_history_count.  */

#define VALUE_HISTORY_CHUNK 60

struct value_history_chunk

  {

    struct value_history_chunk *next;

    struct value *values[VALUE_HISTORY_CHUNK];

  };

/* Chain of chunks now in use.  */

static struct value_history_chunk *value_history_chain;

static int value_history_count; /* Abs number of last entry stored */

/* List of all value objects currently allocated

   (except for those released by calls to release_value)

   This is so they can be freed after each command.  */

static struct value *all_values;

/* Allocate a  value  that has the correct length for type TYPE.  */

struct value *

allocate_value (struct type *type)

{

  struct value *val;

  struct type *atype = check_typedef (type);

  val = (struct value *) xmalloc (sizeof (struct value) + TYPE_LENGTH (atype));

  VALUE_NEXT (val) = all_values;

  all_values = val;

  VALUE_TYPE (val) = type;

  VALUE_ENCLOSING_TYPE (val) = type;

  VALUE_LVAL (val) = not_lval;

  VALUE_ADDRESS (val) = 0;

  VALUE_FRAME (val) = 0;

  VALUE_OFFSET (val) = 0;

  VALUE_BITPOS (val) = 0;

  VALUE_BITSIZE (val) = 0;

  VALUE_REGNO (val) = -1;

  VALUE_LAZY (val) = 0;

  VALUE_OPTIMIZED_OUT (val) = 0;

  VALUE_BFD_SECTION (val) = NULL;

  VALUE_EMBEDDED_OFFSET (val) = 0;

  VALUE_POINTED_TO_OFFSET (val) = 0;

  val->modifiable = 1;

  return val;

}

/* Allocate a  value  that has the correct length

   for COUNT repetitions type TYPE.  */

struct value *

allocate_repeat_value (struct type *type, int count)

{

  int low_bound = current_language->string_lower_bound;         /* ??? */

  /* FIXME-type-allocation: need a way to free this type when we are

     done with it.  */

  struct type *range_type

  = create_range_type ((struct type *) NULL, builtin_type_int,

                       low_bound, count + low_bound - 1);

  /* FIXME-type-allocation: need a way to free this type when we are

     done with it.  */

  return allocate_value (create_array_type ((struct type *) NULL,

                                            type, range_type));

}

/* Return a mark in the value chain.  All values allocated after the

   mark is obtained (except for those released) are subject to being freed

   if a subsequent value_free_to_mark is passed the mark.  */

struct value *

value_mark (void)

{

  return all_values;

}

/* Free all values allocated since MARK was obtained by value_mark

   (except for those released).  */

void

value_free_to_mark (struct value *mark)

{

  struct value *val;

  struct value *next;

  for (val = all_values; val && val != mark; val = next)

    {

      next = VALUE_NEXT (val);

      value_free (val);

    }

  all_values = val;

}

/* Free all the values that have been allocated (except for those released).

   Called after each command, successful or not.  */

void

free_all_values (void)

{

  struct value *val;

  struct value *next;

  for (val = all_values; val; val = next)

    {

      next = VALUE_NEXT (val);

      value_free (val);

    }

  all_values = 0;

}

/* Remove VAL from the chain all_values

   so it will not be freed automatically.  */

void

release_value (struct value *val)

{

  struct value *v;

  if (all_values == val)

    {

      all_values = val->next;

      return;

    }

  for (v = all_values; v; v = v->next)

    {

      if (v->next == val)

        {

          v->next = val->next;

          break;

        }

    }

}

/* Release all values up to mark  */

struct value *

value_release_to_mark (struct value *mark)

{

  struct value *val;

  struct value *next;

  for (val = next = all_values; next; next = VALUE_NEXT (next))

    if (VALUE_NEXT (next) == mark)

      {

        all_values = VALUE_NEXT (next);

        VALUE_NEXT (next) = 0;

        return val;

      }

  all_values = 0;

  return val;

}

/* Return a copy of the value ARG.

   It contains the same contents, for same memory address,

   but it's a different block of storage.  */

struct value *

value_copy (struct value *arg)

{

  register struct type *encl_type = VALUE_ENCLOSING_TYPE (arg);

  struct value *val = allocate_value (encl_type);

  VALUE_TYPE (val) = VALUE_TYPE (arg);

  VALUE_LVAL (val) = VALUE_LVAL (arg);

  VALUE_ADDRESS (val) = VALUE_ADDRESS (arg);

  VALUE_OFFSET (val) = VALUE_OFFSET (arg);

  VALUE_BITPOS (val) = VALUE_BITPOS (arg);

  VALUE_BITSIZE (val) = VALUE_BITSIZE (arg);

  VALUE_FRAME (val) = VALUE_FRAME (arg);

  VALUE_REGNO (val) = VALUE_REGNO (arg);

  VALUE_LAZY (val) = VALUE_LAZY (arg);

  VALUE_OPTIMIZED_OUT (val) = VALUE_OPTIMIZED_OUT (arg);

  VALUE_EMBEDDED_OFFSET (val) = VALUE_EMBEDDED_OFFSET (arg);

  VALUE_POINTED_TO_OFFSET (val) = VALUE_POINTED_TO_OFFSET (arg);

  VALUE_BFD_SECTION (val) = VALUE_BFD_SECTION (arg);

  val->modifiable = arg->modifiable;

  if (!VALUE_LAZY (val))

    {

      memcpy (VALUE_CONTENTS_ALL_RAW (val), VALUE_CONTENTS_ALL_RAW (arg),

              TYPE_LENGTH (VALUE_ENCLOSING_TYPE (arg)));

    }

  return val;

}

/* Access to the value history.  */

/* Record a new value in the value history.

   Returns the absolute history index of the entry.

   Result of -1 indicates the value was not saved; otherwise it is the

   value history index of this new item.  */

int

record_latest_value (struct value *val)

{

  int i;

  /* We don't want this value to have anything to do with the inferior anymore.

     In particular, "set $1 = 50" should not affect the variable from which

     the value was taken, and fast watchpoints should be able to assume that

     a value on the value history never changes.  */

  if (VALUE_LAZY (val))

    value_fetch_lazy (val);

  /* We preserve VALUE_LVAL so that the user can find out where it was fetched

     from.  This is a bit dubious, because then *&$1 does not just return $1

     but the current contents of that location.  c'est la vie...  */

  val->modifiable = 0;

  release_value (val);

  /* Here we treat value_history_count as origin-zero

     and applying to the value being stored now.  */

  i = value_history_count % VALUE_HISTORY_CHUNK;

  if (i == 0)

    {

      struct value_history_chunk *new

      = (struct value_history_chunk *)

      xmalloc (sizeof (struct value_history_chunk));

      memset (new->values, 0, sizeof new->values);

      new->next = value_history_chain;

      value_history_chain = new;

    }

  value_history_chain->values[i] = val;

  /* Now we regard value_history_count as origin-one

     and applying to the value just stored.  */

  return ++value_history_count;

}

/* Return a copy of the value in the history with sequence number NUM.  */

struct value *

access_value_history (int num)

{

  struct value_history_chunk *chunk;

  register int i;

  register int absnum = num;

  if (absnum <= 0)

    absnum += value_history_count;

  if (absnum <= 0)

    {

      if (num == 0)

        error ("The history is empty.");

      else if (num == 1)

        error ("There is only one value in the history.");

      else

        error ("History does not go back to $$%d.", -num);

    }

  if (absnum > value_history_count)

    error ("History has not yet reached $%d.", absnum);

  absnum--;

  /* Now absnum is always absolute and origin zero.  */

  chunk = value_history_chain;

  for (i = (value_history_count - 1) / VALUE_HISTORY_CHUNK - absnum / VALUE_HISTORY_CHUNK;

       i > 0; i--)

    chunk = chunk->next;

  return value_copy (chunk->values[absnum % VALUE_HISTORY_CHUNK]);

}

/* Clear the value history entirely.

   Must be done when new symbol tables are loaded,

   because the type pointers become invalid.  */

void

clear_value_history (void)

{

  struct value_history_chunk *next;

  register int i;

  struct value *val;

  while (value_history_chain)

    {

      for (i = 0; i < VALUE_HISTORY_CHUNK; i++)

        if ((val = value_history_chain->values[i]) != NULL)

          xfree (val);

      next = value_history_chain->next;

      xfree (value_history_chain);

      value_history_chain = next;

    }

  value_history_count = 0;

}

static void

show_values (char *num_exp, int from_tty)

{

  register int i;

  struct value *val;

  static int num = 1;

  if (num_exp)

    {

      /* "info history +" should print from the stored position.

         "info history <exp>" should print around value number <exp>.  */

      if (num_exp[0] != '+' || num_exp[1] != '\0')

        num = parse_and_eval_long (num_exp) - 5;

    }

  else

    {

      /* "info history" means print the last 10 values.  */

      num = value_history_count - 9;

    }

  if (num <= 0)

    num = 1;

  for (i = num; i < num + 10 && i <= value_history_count; i++)

    {

      val = access_value_history (i);

      printf_filtered ("$%d = ", i);

      value_print (val, gdb_stdout, 0, Val_pretty_default);

      printf_filtered ("\n");

    }

  /* The next "info history +" should start after what we just printed.  */

  num += 10;

  /* Hitting just return after this command should do the same thing as

     "info history +".  If num_exp is null, this is unnecessary, since

     "info history +" is not useful after "info history".  */

  if (from_tty && num_exp)

    {

      num_exp[0] = '+';

      num_exp[1] = '\0';

    }

}

/* Internal variables.  These are variables within the debugger

   that hold values assigned by debugger commands.

   The user refers to them with a '$' prefix

   that does not appear in the variable names stored internally.  */

static struct internalvar *internalvars;

/* Look up an internal variable with name NAME.  NAME should not

   normally include a dollar sign.

   If the specified internal variable does not exist,

   one is created, with a void value.  */

struct internalvar *

lookup_internalvar (char *name)

{

  register struct internalvar *var;

  for (var = internalvars; var; var = var->next)

    if (STREQ (var->name, name))

      return var;

  var = (struct internalvar *) xmalloc (sizeof (struct internalvar));

  var->name = concat (name, NULL);

  var->value = allocate_value (builtin_type_void);

  release_value (var->value);

  var->next = internalvars;

  internalvars = var;

  return var;

}

struct value *

value_of_internalvar (struct internalvar *var)

{

  struct value *val;

#ifdef IS_TRAPPED_INTERNALVAR

  if (IS_TRAPPED_INTERNALVAR (var->name))

    return VALUE_OF_TRAPPED_INTERNALVAR (var);

#endif

  val = value_copy (var->value);

  if (VALUE_LAZY (val))

    value_fetch_lazy (val);

  VALUE_LVAL (val) = lval_internalvar;

  VALUE_INTERNALVAR (val) = var;

  return val;

}

void

set_internalvar_component (struct internalvar *var, int offset, int bitpos,

                           int bitsize, struct value *newval)

{

  register char *addr = VALUE_CONTENTS (var->value) + offset;

#ifdef IS_TRAPPED_INTERNALVAR

  if (IS_TRAPPED_INTERNALVAR (var->name))

    SET_TRAPPED_INTERNALVAR (var, newval, bitpos, bitsize, offset);

#endif

  if (bitsize)

    modify_field (addr, value_as_long (newval),

                  bitpos, bitsize);

  else

    memcpy (addr, VALUE_CONTENTS (newval), TYPE_LENGTH (VALUE_TYPE (newval)));

}

void

set_internalvar (struct internalvar *var, struct value *val)

{

  struct value *newval;

#ifdef IS_TRAPPED_INTERNALVAR

  if (IS_TRAPPED_INTERNALVAR (var->name))

    SET_TRAPPED_INTERNALVAR (var, val, 0, 0, 0);

#endif

  newval = value_copy (val);

  newval->modifiable = 1;

  /* Force the value to be fetched from the target now, to avoid problems

     later when this internalvar is referenced and the target is gone or

     has changed.  */

  if (VALUE_LAZY (newval))

    value_fetch_lazy (newval);

  /* Begin code which must not call error().  If var->value points to

     something free'd, an error() obviously leaves a dangling pointer.

     But we also get a danling pointer if var->value points to

     something in the value chain (i.e., before release_value is

     called), because after the error free_all_values will get called before

     long.  */

  xfree (var->value);

  var->value = newval;

  release_value (newval);

  /* End code which must not call error().  */

}

char *

internalvar_name (struct internalvar *var)

{

  return var->name;

}

/* Free all internalvars.  Done when new symtabs are loaded,

   because that makes the values invalid.  */

void

clear_internalvars (void)

{

  register struct internalvar *var;

  while (internalvars)

    {

      var = internalvars;

      internalvars = var->next;

      xfree (var->name);

      xfree (var->value);

      xfree (var);

    }

}

static void

show_convenience (char *ignore, int from_tty)

{

  register struct internalvar *var;

  int varseen = 0;

  for (var = internalvars; var; var = var->next)

    {

#ifdef IS_TRAPPED_INTERNALVAR

      if (IS_TRAPPED_INTERNALVAR (var->name))

        continue;

#endif

      if (!varseen)

        {

          varseen = 1;

        }

      printf_filtered ("$%s = ", var->name);

      value_print (var->value, gdb_stdout, 0, Val_pretty_default);

      printf_filtered ("\n");

    }

  if (!varseen)

    printf_unfiltered ("No debugger convenience variables now defined.\n\

Convenience variables have names starting with \"$\";\n\

use \"set\" as in \"set $foo = 5\" to define them.\n");

}

/* Extract a value as a C number (either long or double).

   Knows how to convert fixed values to double, or

   floating values to long.

   Does not deallocate the value.  */

LONGEST

value_as_long (struct value *val)

{

  /* This coerces arrays and functions, which is necessary (e.g.

     in disassemble_command).  It also dereferences references, which

     I suspect is the most logical thing to do.  */

  COERCE_ARRAY (val);

  return unpack_long (VALUE_TYPE (val), VALUE_CONTENTS (val));

}

DOUBLEST

value_as_double (struct value *val)

{

  DOUBLEST foo;

  int inv;

  foo = unpack_double (VALUE_TYPE (val), VALUE_CONTENTS (val), &inv);

  if (inv)

    error ("Invalid floating value found in program.");

  return foo;

}

/* Extract a value as a C pointer. Does not deallocate the value.

   Note that val's type may not actually be a pointer; value_as_long

   handles all the cases.  */

CORE_ADDR

value_as_address (struct value *val)

{

  /* Assume a CORE_ADDR can fit in a LONGEST (for now).  Not sure

     whether we want this to be true eventually.  */

#if 0

  /* ADDR_BITS_REMOVE is wrong if we are being called for a

     non-address (e.g. argument to "signal", "info break", etc.), or

     for pointers to char, in which the low bits *are* significant.  */

  return ADDR_BITS_REMOVE (value_as_long (val));

#else

  /* There are several targets (IA-64, PowerPC, and others) which

     don't represent pointers to functions as simply the address of

     the function's entry point.  For example, on the IA-64, a

     function pointer points to a two-word descriptor, generated by

     the linker, which contains the function's entry point, and the

     value the IA-64 "global pointer" register should have --- to

     support position-independent code.  The linker generates

     descriptors only for those functions whose addresses are taken.

     On such targets, it's difficult for GDB to convert an arbitrary

     function address into a function pointer; it has to either find

     an existing descriptor for that function, or call malloc and

     build its own.  On some targets, it is impossible for GDB to

     build a descriptor at all: the descriptor must contain a jump

     instruction; data memory cannot be executed; and code memory

     cannot be modified.

     Upon entry to this function, if VAL is a value of type `function'

     (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then

     VALUE_ADDRESS (val) is the address of the function.  This is what

     you'll get if you evaluate an expression like `main'.  The call

     to COERCE_ARRAY below actually does all the usual unary

     conversions, which includes converting values of type `function'

     to `pointer to function'.  This is the challenging conversion

     discussed above.  Then, `unpack_long' will convert that pointer

     back into an address.

     So, suppose the user types `disassemble foo' on an architecture

     with a strange function pointer representation, on which GDB

     cannot build its own descriptors, and suppose further that `foo'

     has no linker-built descriptor.  The address->pointer conversion

     will signal an error and prevent the command from running, even

     though the next step would have been to convert the pointer

     directly back into the same address.

     The following shortcut avoids this whole mess.  If VAL is a

     function, just return its address directly.  */

  if (TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC

      || TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_METHOD)

    return VALUE_ADDRESS (val);

  COERCE_ARRAY (val);

  /* Some architectures (e.g. Harvard), map instruction and data

     addresses onto a single large unified address space.  For

     instance: An architecture may consider a large integer in the

     range 0x10000000 .. 0x1000ffff to already represent a data

     addresses (hence not need a pointer to address conversion) while

     a small integer would still need to be converted integer to

     pointer to address.  Just assume such architectures handle all

     integer conversions in a single function.  */

  /* JimB writes:

     I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we

     must admonish GDB hackers to make sure its behavior matches the

     compiler's, whenever possible.

     In general, I think GDB should evaluate expressions the same way

     the compiler does.  When the user copies an expression out of

     their source code and hands it to a `print' command, they should

     get the same value the compiler would have computed.  Any

     deviation from this rule can cause major confusion and annoyance,

     and needs to be justified carefully.  In other words, GDB doesn't

     really have the freedom to do these conversions in clever and

     useful ways.

     AndrewC pointed out that users aren't complaining about how GDB

     casts integers to pointers; they are complaining that they can't

     take an address from a disassembly listing and give it to `x/i'.

     This is certainly important.

     Adding an architecture method like INTEGER_TO_ADDRESS certainly

     makes it possible for GDB to "get it right" in all circumstances

     --- the target has complete control over how things get done, so

     people can Do The Right Thing for their target without breaking

     anyone else.  The standard doesn't specify how integers get

     converted to pointers; usually, the ABI doesn't either, but

     ABI-specific code is a more reasonable place to handle it.  */

  if (TYPE_CODE (VALUE_TYPE (val)) != TYPE_CODE_PTR

      && TYPE_CODE (VALUE_TYPE (val)) != TYPE_CODE_REF

      && INTEGER_TO_ADDRESS_P ())

    return INTEGER_TO_ADDRESS (VALUE_TYPE (val), VALUE_CONTENTS (val));

  return unpack_long (VALUE_TYPE (val), VALUE_CONTENTS (val));

#endif

}

/* Unpack raw data (copied from debugee, target byte order) at VALADDR

   as a long, or as a double, assuming the raw data is described

   by type TYPE.  Knows how to convert different sizes of values

   and can convert between fixed and floating point.  We don't assume

   any alignment for the raw data.  Return value is in host byte order.

   If you want functions and arrays to be coerced to pointers, and

   references to be dereferenced, call value_as_long() instead.

   C++: It is assumed that the front-end has taken care of

   all matters concerning pointers to members.  A pointer

   to member which reaches here is considered to be equivalent

   to an INT (or some size).  After all, it is only an offset.  */

LONGEST

unpack_long (struct type *type, char *valaddr)

{

  register enum type_code code = TYPE_CODE (type);

  register int len = TYPE_LENGTH (type);

  register int nosign = TYPE_UNSIGNED (type);

  if (current_language->la_language == language_scm

      && is_scmvalue_type (type))

    return scm_unpack (type, valaddr, TYPE_CODE_INT);

  switch (code)

    {

    case TYPE_CODE_TYPEDEF:

      return unpack_long (check_typedef (type), valaddr);

    case TYPE_CODE_ENUM:

    case TYPE_CODE_BOOL:

    case TYPE_CODE_INT:

    case TYPE_CODE_CHAR:

    case TYPE_CODE_RANGE:

      if (nosign)

        return extract_unsigned_integer (valaddr, len);

      else

        return extract_signed_integer (valaddr, len);

    case TYPE_CODE_FLT:

      return extract_typed_floating (valaddr, type);

    case TYPE_CODE_PTR:

    case TYPE_CODE_REF:

      /* Assume a CORE_ADDR can fit in a LONGEST (for now).  Not sure

         whether we want this to be true eventually.  */

      return extract_typed_address (valaddr, type);

    case TYPE_CODE_MEMBER:

      error ("not implemented: member types in unpack_long");

    default:

      error ("Value can't be converted to integer.");

    }

  return 0;                      /* Placate lint.  */

}

/* Return a double value from the specified type and address.

   INVP points to an int which is set to 0 for valid value,

   1 for invalid value (bad float format).  In either case,

   the returned double is OK to use.  Argument is in target