src/FileAbstraction.hpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2005 Apple Computer, Inc. All rights reserved.
   4  *
   5  * @APPLE_LICENSE_HEADER_START@
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   7  * This file contains Original Code and/or Modifications of Original Code
   8  * as defined in and that are subject to the Apple Public Source License
   9  * Version 2.0 (the 'License'). You may not use this file except in
  10  * compliance with the License. Please obtain a copy of the License at
  11  * http://www.opensource.apple.com/apsl/ and read it before using this
  12  * file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  19  * Please see the License for the specific language governing rights and
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  23  */
  24 #ifndef __FILE_ABSTRACTION__
  25 #define __FILE_ABSTRACTION__
  26
  27
  28 #include <stdint.h>
  29 #include <string.h>
  30 #include <libkern/OSByteOrder.h>
  31
  32 #ifdef __OPTIMIZE__
  33 #define INLINE  __attribute__((always_inline))
  34 #else
  35 #define INLINE
  36 #endif
  37
  38 //
  39 // This abstraction layer is for use with file formats that have 64-bit/32-bit and Big-Endian/Little-Endian variants
  40 //
  41 // For example: to make a utility that handles 32-bit little enidan files use:  Pointer32<LittleEndian>
  42 //
  43 //
  44 //              get16()                 read a 16-bit number from an E endian struct
  45 //              set16()                 write a 16-bit number to an E endian struct
  46 //              get32()                 read a 32-bit number from an E endian struct
  47 //              set32()                 write a 32-bit number to an E endian struct
  48 //              get64()                 read a 64-bit number from an E endian struct
  49 //              set64()                 write a 64-bit number to an E endian struct
  50 //
  51 //              getBits()               read a bit field from an E endian struct (bitCount=number of bits in field, firstBit=bit index of field)
  52 //              setBits()               write a bit field to an E endian struct (bitCount=number of bits in field, firstBit=bit index of field)
  53 //
  54 //              getBitsRaw()    read a bit field from a struct with native endianness
  55 //              setBitsRaw()    write a bit field from a struct with native endianness
  56 //
  57
  58 class BigEndian
  59 {
  60 public:
  61         static uint16_t get16(const uint16_t& from)                             INLINE { return OSReadBigInt16(&from, 0); }
  62         static void             set16(uint16_t& into, uint16_t value)   INLINE { OSWriteBigInt16(&into, 0, value); }
  63
  64         static uint32_t get32(const uint32_t& from)                             INLINE { return OSReadBigInt32(&from, 0); }
  65         static void             set32(uint32_t& into, uint32_t value)   INLINE { OSWriteBigInt32(&into, 0, value); }
  66
  67         static uint64_t get64(const uint64_t& from)                             INLINE { return OSReadBigInt64(&from, 0); }
  68         static void             set64(uint64_t& into, uint64_t value)   INLINE { OSWriteBigInt64(&into, 0, value); }
  69
  70         static uint32_t getBits(const uint32_t& from,
  71                                                 uint8_t firstBit, uint8_t bitCount)     INLINE { return getBitsRaw(get32(from), firstBit, bitCount); }
  72         static void             setBits(uint32_t& into, uint32_t value,
  73                                                 uint8_t firstBit, uint8_t bitCount)     INLINE { uint32_t temp = get32(into); setBitsRaw(temp, value, firstBit, bitCount); set32(into, temp); }
  74
  75         static uint32_t getBitsRaw(const uint32_t& from,
  76                                                 uint8_t firstBit, uint8_t bitCount)     INLINE { return ((from >> (32-firstBit-bitCount)) & ((1<<bitCount)-1)); }
  77         static void             setBitsRaw(uint32_t& into, uint32_t value,
  78                                                 uint8_t firstBit, uint8_t bitCount)     INLINE { uint32_t temp = into;
  79                                                                                                                                                                                         const uint32_t mask = ((1<<bitCount)-1);
  80                                                                                                                                                                                         temp &= ~(mask << (32-firstBit-bitCount));
  81                                                                                                                                                                                         temp |= ((value & mask) << (32-firstBit-bitCount));
  82                                                                                                                                                                                         into = temp; }
  83         enum { little_endian = 0 };
  84 };
  85
  86
  87 class LittleEndian
  88 {
  89 public:
  90         static uint16_t get16(const uint16_t& from)                             INLINE { return OSReadLittleInt16(&from, 0); }
  91         static void             set16(uint16_t& into, uint16_t value)   INLINE { OSWriteLittleInt16(&into, 0, value); }
  92
  93         static uint32_t get32(const uint32_t& from)                             INLINE { return OSReadLittleInt32(&from, 0); }
  94         static void             set32(uint32_t& into, uint32_t value)   INLINE { OSWriteLittleInt32(&into, 0, value); }
  95
  96         static uint64_t get64(const uint64_t& from)                             INLINE { return OSReadLittleInt64(&from, 0); }
  97         static void             set64(uint64_t& into, uint64_t value)   INLINE { OSWriteLittleInt64(&into, 0, value); }
  98
  99         static uint32_t getBits(const uint32_t& from,
 100                                                 uint8_t firstBit, uint8_t bitCount)     INLINE { return getBitsRaw(get32(from), firstBit, bitCount); }
 101         static void             setBits(uint32_t& into, uint32_t value,
 102                                                 uint8_t firstBit, uint8_t bitCount)     INLINE { uint32_t temp = get32(into); setBitsRaw(temp, value, firstBit, bitCount); set32(into, temp); }
 103
 104         static uint32_t getBitsRaw(const uint32_t& from,
 105                                                 uint8_t firstBit, uint8_t bitCount)     INLINE { return ((from >> firstBit) & ((1<<bitCount)-1)); }
 106         static void             setBitsRaw(uint32_t& into, uint32_t value,
 107                                                 uint8_t firstBit, uint8_t bitCount)     INLINE {  uint32_t temp = into;
 108                                                                                                                                                                                         const uint32_t mask = ((1<<bitCount)-1);
 109                                                                                                                                                                                         temp &= ~(mask << firstBit);
 110                                                                                                                                                                                         temp |= ((value & mask) << firstBit);
 111                                                                                                                                                                                         into = temp; }
 112         enum { little_endian = 1 };
 113 };
 114
 115
 116 template <typename _E>
 117 class Pointer32
 118 {
 119 public:
 120         typedef uint32_t        uint_t;
 121         typedef _E                      E;
 122
 123         static uint64_t getP(const uint_t& from)                                INLINE { return _E::get32(from); }
 124         static void             setP(uint_t& into, uint64_t value)              INLINE { _E::set32(into, value); }
 125 };
 126
 127
 128 template <typename _E>
 129 class Pointer64
 130 {
 131 public:
 132         typedef uint64_t        uint_t;
 133         typedef _E                      E;
 134
 135         static uint64_t getP(const uint_t& from)                                INLINE { return _E::get64(from); }
 136         static void             setP(uint_t& into, uint64_t value)              INLINE { _E::set64(into, value); }
 137 };
 138
 139
 140
 141
 142
 143 #endif // __FILE_ABSTRACTION__
 144
 145