FileAbstraction.hpp [plain text]
/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
*
* Copyright (c) 2005 Apple Computer, Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
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*/
#ifndef __FILE_ABSTRACTION__
#define __FILE_ABSTRACTION__
#include <stdint.h>
#include <string.h>
#include <libkern/OSByteOrder.h>
#ifdef __OPTIMIZE__
#define INLINE __attribute__((always_inline))
#else
#define INLINE
#endif
//
// This abstraction layer is for use with file formats that have 64-bit/32-bit and Big-Endian/Little-Endian variants
//
// For example: to make a utility that handles 32-bit little enidan files use: Pointer32<LittleEndian>
//
//
// get16() read a 16-bit number from an E endian struct
// set16() write a 16-bit number to an E endian struct
// get32() read a 32-bit number from an E endian struct
// set32() write a 32-bit number to an E endian struct
// get64() read a 64-bit number from an E endian struct
// set64() write a 64-bit number to an E endian struct
//
// getBits() read a bit field from an E endian struct (bitCount=number of bits in field, firstBit=bit index of field)
// setBits() write a bit field to an E endian struct (bitCount=number of bits in field, firstBit=bit index of field)
//
// getBitsRaw() read a bit field from a struct with native endianness
// setBitsRaw() write a bit field from a struct with native endianness
//
class BigEndian
{
public:
static uint16_t get16(const uint16_t& from) INLINE { return OSReadBigInt16(&from, 0); }
static void set16(uint16_t& into, uint16_t value) INLINE { OSWriteBigInt16(&into, 0, value); }
static uint32_t get32(const uint32_t& from) INLINE { return OSReadBigInt32(&from, 0); }
static void set32(uint32_t& into, uint32_t value) INLINE { OSWriteBigInt32(&into, 0, value); }
static uint64_t get64(const uint64_t& from) INLINE { return OSReadBigInt64(&from, 0); }
static void set64(uint64_t& into, uint64_t value) INLINE { OSWriteBigInt64(&into, 0, value); }
static uint32_t getBits(const uint32_t& from,
uint8_t firstBit, uint8_t bitCount) INLINE { return getBitsRaw(get32(from), firstBit, bitCount); }
static void setBits(uint32_t& into, uint32_t value,
uint8_t firstBit, uint8_t bitCount) INLINE { uint32_t temp = get32(into); setBitsRaw(temp, value, firstBit, bitCount); set32(into, temp); }
static uint32_t getBitsRaw(const uint32_t& from,
uint8_t firstBit, uint8_t bitCount) INLINE { return ((from >> (32-firstBit-bitCount)) & ((1<<bitCount)-1)); }
static void setBitsRaw(uint32_t& into, uint32_t value,
uint8_t firstBit, uint8_t bitCount) INLINE { uint32_t temp = into;
const uint32_t mask = ((1<<bitCount)-1);
temp &= ~(mask << (32-firstBit-bitCount));
temp |= ((value & mask) << (32-firstBit-bitCount));
into = temp; }
enum { little_endian = 0 };
};
class LittleEndian
{
public:
static uint16_t get16(const uint16_t& from) INLINE { return OSReadLittleInt16(&from, 0); }
static void set16(uint16_t& into, uint16_t value) INLINE { OSWriteLittleInt16(&into, 0, value); }
static uint32_t get32(const uint32_t& from) INLINE { return OSReadLittleInt32(&from, 0); }
static void set32(uint32_t& into, uint32_t value) INLINE { OSWriteLittleInt32(&into, 0, value); }
static uint64_t get64(const uint64_t& from) INLINE { return OSReadLittleInt64(&from, 0); }
static void set64(uint64_t& into, uint64_t value) INLINE { OSWriteLittleInt64(&into, 0, value); }
static uint32_t getBits(const uint32_t& from,
uint8_t firstBit, uint8_t bitCount) INLINE { return getBitsRaw(get32(from), firstBit, bitCount); }
static void setBits(uint32_t& into, uint32_t value,
uint8_t firstBit, uint8_t bitCount) INLINE { uint32_t temp = get32(into); setBitsRaw(temp, value, firstBit, bitCount); set32(into, temp); }
static uint32_t getBitsRaw(const uint32_t& from,
uint8_t firstBit, uint8_t bitCount) INLINE { return ((from >> firstBit) & ((1<<bitCount)-1)); }
static void setBitsRaw(uint32_t& into, uint32_t value,
uint8_t firstBit, uint8_t bitCount) INLINE { uint32_t temp = into;
const uint32_t mask = ((1<<bitCount)-1);
temp &= ~(mask << firstBit);
temp |= ((value & mask) << firstBit);
into = temp; }
enum { little_endian = 1 };
};
template <typename _E>
class Pointer32
{
public:
typedef uint32_t uint_t;
typedef _E E;
static uint64_t getP(const uint_t& from) INLINE { return _E::get32(from); }
static void setP(uint_t& into, uint64_t value) INLINE { _E::set32(into, value); }
};
template <typename _E>
class Pointer64
{
public:
typedef uint64_t uint_t;
typedef _E E;
static uint64_t getP(const uint_t& from) INLINE { return _E::get64(from); }
static void setP(uint_t& into, uint64_t value) INLINE { _E::set64(into, value); }
};
#endif // __FILE_ABSTRACTION__