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      1 
      2 /*
      3  * Copyright 2006 The Android Open Source Project
      4  *
      5  * Use of this source code is governed by a BSD-style license that can be
      6  * found in the LICENSE file.
      7  */
      8 
      9 
     10 #ifndef SkEndian_DEFINED
     11 #define SkEndian_DEFINED
     12 
     13 #include "SkTypes.h"
     14 
     15 /** \file SkEndian.h
     16 
     17     Macros and helper functions for handling 16 and 32 bit values in
     18     big and little endian formats.
     19 */
     20 
     21 #if defined(SK_CPU_LENDIAN) && defined(SK_CPU_BENDIAN)
     22     #error "can't have both LENDIAN and BENDIAN defined"
     23 #endif
     24 
     25 #if !defined(SK_CPU_LENDIAN) && !defined(SK_CPU_BENDIAN)
     26     #error "need either LENDIAN or BENDIAN defined"
     27 #endif
     28 
     29 /** Swap the two bytes in the low 16bits of the parameters.
     30     e.g. 0x1234 -> 0x3412
     31 */
     32 static inline uint16_t SkEndianSwap16(U16CPU value) {
     33     SkASSERT(value == (uint16_t)value);
     34     return static_cast<uint16_t>((value >> 8) | (value << 8));
     35 }
     36 template<uint16_t N> struct SkTEndianSwap16 {
     37     static const uint16_t value = static_cast<uint16_t>((N >> 8) | ((N & 0xFF) << 8));
     38 };
     39 
     40 /** Vector version of SkEndianSwap16(), which swaps the
     41     low two bytes of each value in the array.
     42 */
     43 static inline void SkEndianSwap16s(uint16_t array[], int count) {
     44     SkASSERT(count == 0 || array != NULL);
     45 
     46     while (--count >= 0) {
     47         *array = SkEndianSwap16(*array);
     48         array += 1;
     49     }
     50 }
     51 
     52 /** Reverse all 4 bytes in a 32bit value.
     53     e.g. 0x12345678 -> 0x78563412
     54 */
     55 static inline uint32_t SkEndianSwap32(uint32_t value) {
     56     return  ((value & 0xFF) << 24) |
     57             ((value & 0xFF00) << 8) |
     58             ((value & 0xFF0000) >> 8) |
     59             (value >> 24);
     60 }
     61 template<uint32_t N> struct SkTEndianSwap32 {
     62     static const uint32_t value = ((N & 0xFF) << 24) |
     63                                   ((N & 0xFF00) << 8) |
     64                                   ((N & 0xFF0000) >> 8) |
     65                                   (N >> 24);
     66 };
     67 
     68 /** Vector version of SkEndianSwap16(), which swaps the
     69     bytes of each value in the array.
     70 */
     71 static inline void SkEndianSwap32s(uint32_t array[], int count) {
     72     SkASSERT(count == 0 || array != NULL);
     73 
     74     while (--count >= 0) {
     75         *array = SkEndianSwap32(*array);
     76         array += 1;
     77     }
     78 }
     79 
     80 #ifdef SK_CPU_LENDIAN
     81     #define SkEndian_SwapBE16(n)    SkEndianSwap16(n)
     82     #define SkEndian_SwapBE32(n)    SkEndianSwap32(n)
     83     #define SkEndian_SwapLE16(n)    (n)
     84     #define SkEndian_SwapLE32(n)    (n)
     85 
     86     #define SkTEndian_SwapBE16(n)    SkTEndianSwap16<n>::value
     87     #define SkTEndian_SwapBE32(n)    SkTEndianSwap32<n>::value
     88     #define SkTEndian_SwapLE16(n)    (n)
     89     #define SkTEndian_SwapLE32(n)    (n)
     90 #else   // SK_CPU_BENDIAN
     91     #define SkEndian_SwapBE16(n)    (n)
     92     #define SkEndian_SwapBE32(n)    (n)
     93     #define SkEndian_SwapLE16(n)    SkEndianSwap16(n)
     94     #define SkEndian_SwapLE32(n)    SkEndianSwap32(n)
     95 
     96     #define SkTEndian_SwapBE16(n)    (n)
     97     #define SkTEndian_SwapBE32(n)    (n)
     98     #define SkTEndian_SwapLE16(n)    SkTEndianSwap16<n>::value
     99     #define SkTEndian_SwapLE32(n)    SkTEndianSwap32<n>::value
    100 #endif
    101 
    102 // When a bytestream is embedded in a 32-bit word, how far we need to
    103 // shift the word to extract each byte from the low 8 bits by anding with 0xff.
    104 #ifdef SK_CPU_LENDIAN
    105     #define SkEndian_Byte0Shift 0
    106     #define SkEndian_Byte1Shift 8
    107     #define SkEndian_Byte2Shift 16
    108     #define SkEndian_Byte3Shift 24
    109 #else   // SK_CPU_BENDIAN
    110     #define SkEndian_Byte0Shift 24
    111     #define SkEndian_Byte1Shift 16
    112     #define SkEndian_Byte2Shift 8
    113     #define SkEndian_Byte3Shift 0
    114 #endif
    115 
    116 
    117 #if defined(SK_UINT8_BITFIELD_LENDIAN) && defined(SK_UINT8_BITFIELD_BENDIAN)
    118     #error "can't have both bitfield LENDIAN and BENDIAN defined"
    119 #endif
    120 
    121 #if !defined(SK_UINT8_BITFIELD_LENDIAN) && !defined(SK_UINT8_BITFIELD_BENDIAN)
    122     #ifdef SK_CPU_LENDIAN
    123         #define SK_UINT8_BITFIELD_LENDIAN
    124     #else
    125         #define SK_UINT8_BITFIELD_BENDIAN
    126     #endif
    127 #endif
    128 
    129 #ifdef SK_UINT8_BITFIELD_LENDIAN
    130     #define SK_UINT8_BITFIELD(f0, f1, f2, f3, f4, f5, f6, f7) \
    131         SK_OT_BYTE f0 : 1; \
    132         SK_OT_BYTE f1 : 1; \
    133         SK_OT_BYTE f2 : 1; \
    134         SK_OT_BYTE f3 : 1; \
    135         SK_OT_BYTE f4 : 1; \
    136         SK_OT_BYTE f5 : 1; \
    137         SK_OT_BYTE f6 : 1; \
    138         SK_OT_BYTE f7 : 1;
    139 #else
    140     #define SK_UINT8_BITFIELD(f0, f1, f2, f3, f4, f5, f6, f7) \
    141         SK_OT_BYTE f7 : 1; \
    142         SK_OT_BYTE f6 : 1; \
    143         SK_OT_BYTE f5 : 1; \
    144         SK_OT_BYTE f4 : 1; \
    145         SK_OT_BYTE f3 : 1; \
    146         SK_OT_BYTE f2 : 1; \
    147         SK_OT_BYTE f1 : 1; \
    148         SK_OT_BYTE f0 : 1;
    149 #endif
    150 
    151 #endif
    152 
    153