libdw/memory-access.h

/* Unaligned memory access functionality.
   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005 Red Hat, Inc.
   Written by Ulrich Drepper <drepper@redhat.com>, 2001.

   This program is Open Source software; you can redistribute it and/or
   modify it under the terms of the Open Software License version 1.0 as
   published by the Open Source Initiative.

   You should have received a copy of the Open Software License along
   with this program; if not, you may obtain a copy of the Open Software
   License version 1.0 from http://www.opensource.org/licenses/osl.php or
   by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
   3001 King Ranch Road, Ukiah, CA 95482.   */

#ifndef _MEMORY_ACCESS_H
#define _MEMORY_ACCESS_H 1

#include <byteswap.h>
#include <limits.h>
#include <stdint.h>


/* Number decoding macros.  See 7.6 Variable Length Data.  */

#define get_uleb128_step(var, addr, nth, break)				      \
    __b = *(addr)++;							      \
    var |= (uintmax_t) (__b & 0x7f) << (nth * 7);			      \
    if (likely ((__b & 0x80) == 0))					      \
      break

#define get_uleb128(var, addr)						      \
  do {									      \
    unsigned char __b;							      \
    var = 0;								      \
    get_uleb128_step (var, addr, 0, break);				      \
    var = __libdw_get_uleb128 (var, 1, &(addr));			      \
  } while (0)

#define get_uleb128_rest_return(var, i, addrp)				      \
  do {									      \
    for (; i < 10; ++i)							      \
      {									      \
	get_uleb128_step (var, *addrp, i, return var);			      \
      }									      \
    /* Other implementations set VALUE to UINT_MAX in this		      \
       case.  So we better do this as well.  */				      \
    return UINT64_MAX;							      \
  } while (0)

/* The signed case is similar, but we sign-extend the result.  */

#define get_sleb128_step(var, addr, nth, break)				      \
    __b = *(addr)++;							      \
    _v |= (uint64_t) (__b & 0x7f) << (nth * 7);				      \
    if (likely ((__b & 0x80) == 0))					      \
      {									      \
	var = (_v << (64 - (nth * 7) - 7) >> (64 - (nth * 7) - 7));	      \
        break;					 			      \
      }									      \
    else do {} while (0)

#define get_sleb128(var, addr)						      \
  do {									      \
    unsigned char __b;							      \
    int64_t _v = 0;							      \
    get_sleb128_step (var, addr, 0, break);				      \
    var = __libdw_get_sleb128 (_v, 1, &(addr));				      \
  } while (0)

#define get_sleb128_rest_return(var, i, addrp)				      \
  do {									      \
    for (; i < 9; ++i)							      \
      {									      \
	get_sleb128_step (var, *addrp, i, return var);			      \
      }									      \
    /* Other implementations set VALUE to INT_MAX in this		      \
       case.  So we better do this as well.  */				      \
    return INT64_MAX;							      \
  } while (0)

#ifdef IS_LIBDW
extern uint64_t __libdw_get_uleb128 (uint64_t acc, unsigned int i,
				     const unsigned char **addrp)
     internal_function attribute_hidden;
extern int64_t __libdw_get_sleb128 (int64_t acc, unsigned int i,
				    const unsigned char **addrp)
     internal_function attribute_hidden;
#else
static uint64_t
__attribute__ ((unused))
__libdw_get_uleb128 (uint64_t acc, unsigned int i, const unsigned char **addrp)
{
  unsigned char __b;
  get_uleb128_rest_return (acc, i, addrp);
}
static int64_t
__attribute__ ((unused))
__libdw_get_sleb128 (int64_t acc, unsigned int i, const unsigned char **addrp)
{
  unsigned char __b;
  int64_t _v = acc;
  get_sleb128_rest_return (acc, i, addrp);
}
#endif


/* We use simple memory access functions in case the hardware allows it.
   The caller has to make sure we don't have alias problems.  */
#if ALLOW_UNALIGNED

# define read_2ubyte_unaligned(Dbg, Addr) \
  (unlikely ((Dbg)->other_byte_order)					      \
   ? bswap_16 (*((const uint16_t *) (Addr)))				      \
   : *((const uint16_t *) (Addr)))
# define read_2sbyte_unaligned(Dbg, Addr) \
  (unlikely ((Dbg)->other_byte_order)					      \
   ? (int16_t) bswap_16 (*((const int16_t *) (Addr)))			      \
   : *((const int16_t *) (Addr)))

# define read_4ubyte_unaligned_noncvt(Addr) \
   *((const uint32_t *) (Addr))
# define read_4ubyte_unaligned(Dbg, Addr) \
  (unlikely ((Dbg)->other_byte_order)					      \
   ? bswap_32 (*((const uint32_t *) (Addr)))				      \
   : *((const uint32_t *) (Addr)))
# define read_4sbyte_unaligned(Dbg, Addr) \
  (unlikely ((Dbg)->other_byte_order)					      \
   ? (int32_t) bswap_32 (*((const int32_t *) (Addr)))			      \
   : *((const int32_t *) (Addr)))

# define read_8ubyte_unaligned(Dbg, Addr) \
  (unlikely ((Dbg)->other_byte_order)					      \
   ? bswap_64 (*((const uint64_t *) (Addr)))				      \
   : *((const uint64_t *) (Addr)))
# define read_8sbyte_unaligned(Dbg, Addr) \
  (unlikely ((Dbg)->other_byte_order)					      \
   ? (int64_t) bswap_64 (*((const int64_t *) (Addr)))			      \
   : *((const int64_t *) (Addr)))

#else

union unaligned
  {
    void *p;
    uint16_t u2;
    uint32_t u4;
    uint64_t u8;
    int16_t s2;
    int32_t s4;
    int64_t s8;
  } __attribute__ ((packed));

static inline uint16_t
read_2ubyte_unaligned (Dwarf *dbg, const void *p)
{
  const union unaligned *up = p;
  if (dbg->other_byte_order)
    return bswap_16 (up->u2);
  return up->u2;
}
static inline int16_t
read_2sbyte_unaligned (Dwarf *dbg, const void *p)
{
  const union unaligned *up = p;
  if (dbg->other_byte_order)
    return (int16_t) bswap_16 (up->u2);
  return up->s2;
}

static inline uint32_t
read_4ubyte_unaligned_noncvt (const void *p)
{
  const union unaligned *up = p;
  return up->u4;
}
static inline uint32_t
read_4ubyte_unaligned (Dwarf *dbg, const void *p)
{
  const union unaligned *up = p;
  if (dbg->other_byte_order)
    return bswap_32 (up->u4);
  return up->u4;
}
static inline int32_t
read_4sbyte_unaligned (Dwarf *dbg, const void *p)
{
  const union unaligned *up = p;
  if (dbg->other_byte_order)
    return (int32_t) bswap_32 (up->u4);
  return up->s4;
}

static inline uint64_t
read_8ubyte_unaligned (Dwarf *dbg, const void *p)
{
  const union unaligned *up = p;
  if (dbg->other_byte_order)
    return bswap_64 (up->u8);
  return up->u8;
}
static inline int64_t
read_8sbyte_unaligned (Dwarf *dbg, const void *p)
{
  const union unaligned *up = p;
  if (dbg->other_byte_order)
    return (int64_t) bswap_64 (up->u8);
  return up->s8;
}

#endif	/* allow unaligned */


#define read_2ubyte_unaligned_inc(Dbg, Addr) \
  ({ uint16_t t_ = read_2ubyte_unaligned (Dbg, Addr);			      \
     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2);		      \
     t_; })
#define read_2sbyte_unaligned_inc(Dbg, Addr) \
  ({ int16_t t_ = read_2sbyte_unaligned (Dbg, Addr);			      \
     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 2);		      \
     t_; })

#define read_4ubyte_unaligned_inc(Dbg, Addr) \
  ({ uint32_t t_ = read_4ubyte_unaligned (Dbg, Addr);			      \
     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4);		      \
     t_; })
#define read_4sbyte_unaligned_inc(Dbg, Addr) \
  ({ int32_t t_ = read_4sbyte_unaligned (Dbg, Addr);			      \
     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 4);		      \
     t_; })

#define read_8ubyte_unaligned_inc(Dbg, Addr) \
  ({ uint64_t t_ = read_8ubyte_unaligned (Dbg, Addr);			      \
     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8);		      \
     t_; })
#define read_8sbyte_unaligned_inc(Dbg, Addr) \
  ({ int64_t t_ = read_8sbyte_unaligned (Dbg, Addr);			      \
     Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 8);		      \
     t_; })

#endif	/* memory-access.h */