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/* Exception handling and frame unwind runtime interface routines.

   Copyright (C) 2001, 2002, 2003, 2004, 2008, 2009 Free Software Foundation, Inc.

   This file is part of GCC.

   GCC 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, or (at your option)

   any later version.

   GCC 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.

   Under Section 7 of GPL version 3, you are granted additional

   permissions described in the GCC Runtime Library Exception, version

   3.1, as published by the Free Software Foundation.

   You should have received a copy of the GNU General Public License and

   a copy of the GCC Runtime Library Exception along with this program;

   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

   <http://www.gnu.org/licenses/>.  */

/* @@@ Really this should be out of line, but this also causes link

   compatibility problems with the base ABI.  This is slightly better

   than duplicating code, however.  */

#ifndef GCC_UNWIND_PE_H

#define GCC_UNWIND_PE_H

/* If using C++, references to abort have to be qualified with std::.  */

#if __cplusplus

#define __gxx_abort std::abort

#else

#define __gxx_abort abort

#endif

/* Pointer encodings, from dwarf2.h.  */

#define DW_EH_PE_absptr         0x00

#define DW_EH_PE_omit           0xff

#define DW_EH_PE_uleb128        0x01

#define DW_EH_PE_udata2         0x02

#define DW_EH_PE_udata4         0x03

#define DW_EH_PE_udata8         0x04

#define DW_EH_PE_sleb128        0x09

#define DW_EH_PE_sdata2         0x0A

#define DW_EH_PE_sdata4         0x0B

#define DW_EH_PE_sdata8         0x0C

#define DW_EH_PE_signed         0x08

#define DW_EH_PE_pcrel          0x10

#define DW_EH_PE_textrel        0x20

#define DW_EH_PE_datarel        0x30

#define DW_EH_PE_funcrel        0x40

#define DW_EH_PE_aligned        0x50

#define DW_EH_PE_indirect       0x80

#ifndef NO_SIZE_OF_ENCODED_VALUE

/* Given an encoding, return the number of bytes the format occupies.

   This is only defined for fixed-size encodings, and so does not

   include leb128.  */

static unsigned int

size_of_encoded_value (unsigned char encoding) __attribute__ ((unused));

static unsigned int

size_of_encoded_value (unsigned char encoding)

{

  if (encoding == DW_EH_PE_omit)

    return 0;

  switch (encoding & 0x07)

    {

    case DW_EH_PE_absptr:

      return sizeof (void *);

    case DW_EH_PE_udata2:

      return 2;

    case DW_EH_PE_udata4:

      return 4;

    case DW_EH_PE_udata8:

      return 8;

    }

  __gxx_abort ();

}

#endif

#ifndef NO_BASE_OF_ENCODED_VALUE

/* Given an encoding and an _Unwind_Context, return the base to which

   the encoding is relative.  This base may then be passed to

   read_encoded_value_with_base for use when the _Unwind_Context is

   not available.  */

static _Unwind_Ptr

base_of_encoded_value (unsigned char encoding, struct _Unwind_Context *context)

{

  if (encoding == DW_EH_PE_omit)

    return 0;

  switch (encoding & 0x70)

    {

    case DW_EH_PE_absptr:

    case DW_EH_PE_pcrel:

    case DW_EH_PE_aligned:

      return 0;

    case DW_EH_PE_textrel:

      return _Unwind_GetTextRelBase (context);

    case DW_EH_PE_datarel:

      return _Unwind_GetDataRelBase (context);

    case DW_EH_PE_funcrel:

      return _Unwind_GetRegionStart (context);

    }

  __gxx_abort ();

}

#endif

/* Read an unsigned leb128 value from P, store the value in VAL, return

   P incremented past the value.  We assume that a word is large enough to

   hold any value so encoded; if it is smaller than a pointer on some target,

   pointers should not be leb128 encoded on that target.  */

static const unsigned char *

read_uleb128 (const unsigned char *p, _uleb128_t *val)

{

  unsigned int shift = 0;

  unsigned char byte;

  _uleb128_t result;

  result = 0;

  do

    {

      byte = *p++;

      result |= ((_uleb128_t)byte & 0x7f) << shift;

      shift += 7;

    }

  while (byte & 0x80);

  *val = result;

  return p;

}

/* Similar, but read a signed leb128 value.  */

static const unsigned char *

read_sleb128 (const unsigned char *p, _sleb128_t *val)

{

  unsigned int shift = 0;

  unsigned char byte;

  _uleb128_t result;

  result = 0;

  do

    {

      byte = *p++;

      result |= ((_uleb128_t)byte & 0x7f) << shift;

      shift += 7;

    }

  while (byte & 0x80);

  /* Sign-extend a negative value.  */

  if (shift < 8 * sizeof(result) && (byte & 0x40) != 0)

    result |= -(((_uleb128_t)1L) << shift);

  *val = (_sleb128_t) result;

  return p;

}

/* Load an encoded value from memory at P.  The value is returned in VAL;

   The function returns P incremented past the value.  BASE is as given

   by base_of_encoded_value for this encoding in the appropriate context.  */

static const unsigned char *

read_encoded_value_with_base (unsigned char encoding, _Unwind_Ptr base,

                              const unsigned char *p, _Unwind_Ptr *val)

{

  union unaligned

    {

      void *ptr;

      unsigned u2 __attribute__ ((mode (HI)));

      unsigned u4 __attribute__ ((mode (SI)));

      unsigned u8 __attribute__ ((mode (DI)));

      signed s2 __attribute__ ((mode (HI)));

      signed s4 __attribute__ ((mode (SI)));

      signed s8 __attribute__ ((mode (DI)));

    } __attribute__((__packed__));

  const union unaligned *u = (const union unaligned *) p;

  _Unwind_Internal_Ptr result;

  if (encoding == DW_EH_PE_aligned)

    {

      _Unwind_Internal_Ptr a = (_Unwind_Internal_Ptr) p;

      a = (a + sizeof (void *) - 1) & - sizeof(void *);

      result = *(_Unwind_Internal_Ptr *) a;

      p = (const unsigned char *) (_Unwind_Internal_Ptr) (a + sizeof (void *));

    }

  else

    {

      switch (encoding & 0x0f)

        {

        case DW_EH_PE_absptr:

          result = (_Unwind_Internal_Ptr) u->ptr;

          p += sizeof (void *);

          break;

        case DW_EH_PE_uleb128:

          {

            _uleb128_t tmp;

            p = read_uleb128 (p, &tmp);

            result = (_Unwind_Internal_Ptr) tmp;

          }

          break;

        case DW_EH_PE_sleb128:

          {

            _sleb128_t tmp;

            p = read_sleb128 (p, &tmp);

            result = (_Unwind_Internal_Ptr) tmp;

          }

          break;

        case DW_EH_PE_udata2:

          result = u->u2;

          p += 2;

          break;

        case DW_EH_PE_udata4:

          result = u->u4;

          p += 4;

          break;

        case DW_EH_PE_udata8:

          result = u->u8;

          p += 8;

          break;

        case DW_EH_PE_sdata2:

          result = u->s2;

          p += 2;

          break;

        case DW_EH_PE_sdata4:

          result = u->s4;

          p += 4;

          break;

        case DW_EH_PE_sdata8:

          result = u->s8;

          p += 8;

          break;

        default:

          __gxx_abort ();

        }

      if (result != 0)

        {

          result += ((encoding & 0x70) == DW_EH_PE_pcrel

                     ? (_Unwind_Internal_Ptr) u : base);

          if (encoding & DW_EH_PE_indirect)

            result = *(_Unwind_Internal_Ptr *) result;

        }

    }

  *val = result;

  return p;

}

#ifndef NO_BASE_OF_ENCODED_VALUE

/* Like read_encoded_value_with_base, but get the base from the context

   rather than providing it directly.  */

static inline const unsigned char *

read_encoded_value (struct _Unwind_Context *context, unsigned char encoding,

                    const unsigned char *p, _Unwind_Ptr *val)

{

  return read_encoded_value_with_base (encoding,

                base_of_encoded_value (encoding, context),

                p, val);

}

#endif

#endif /* unwind-pe.h */