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*/
32static inline uint16_t SkEndianSwap16(U16CPU value) {
33    SkASSERT(value == (uint16_t)value);
34    return static_cast<uint16_t>((value >> 8) | (value << 8));
35}
36template<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*/
43static 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*/
55static inline uint32_t SkEndianSwap32(uint32_t value) {
56    return  ((value & 0xFF) << 24) |
57            ((value & 0xFF00) << 8) |
58            ((value & 0xFF0000) >> 8) |
59            (value >> 24);
60}
61template<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*/
71static 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