1 /*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #ifndef SkEndian_DEFINED
9 #define SkEndian_DEFINED
10
11 #include "include/private/base/SkAssert.h"
12 #include "include/private/base/SkFeatures.h"
13
14 #include <cstdint>
15
16 /** \file SkEndian.h
17
18 Macros and helper functions for handling 16 and 32 bit values in
19 big and little endian formats.
20 */
21
22 #if defined(SK_CPU_LENDIAN) && defined(SK_CPU_BENDIAN)
23 #error "can't have both LENDIAN and BENDIAN defined"
24 #endif
25
26 #if !defined(SK_CPU_LENDIAN) && !defined(SK_CPU_BENDIAN)
27 #error "need either LENDIAN or BENDIAN defined"
28 #endif
29
30 /** Swap the two bytes in the low 16bits of the parameters.
31 e.g. 0x1234 -> 0x3412
32 */
SkEndianSwap16(uint16_t value)33 static inline uint16_t SkEndianSwap16(uint16_t value) {
34 return static_cast<uint16_t>((value >> 8) | ((value & 0xFF) << 8));
35 }
36
37 template<uint16_t N> struct SkTEndianSwap16 {
38 static const uint16_t value = static_cast<uint16_t>((N >> 8) | ((N & 0xFF) << 8));
39 };
40
41 /** Vector version of SkEndianSwap16(), which swaps the
42 low two bytes of each value in the array.
43 */
SkEndianSwap16s(uint16_t array[],int count)44 static inline void SkEndianSwap16s(uint16_t array[], int count) {
45 SkASSERT(count == 0 || array != nullptr);
46
47 while (--count >= 0) {
48 *array = SkEndianSwap16(*array);
49 array += 1;
50 }
51 }
52
53 /** Reverse all 4 bytes in a 32bit value.
54 e.g. 0x12345678 -> 0x78563412
55 */
SkEndianSwap32(uint32_t value)56 static constexpr uint32_t SkEndianSwap32(uint32_t value) {
57 return ((value & 0xFF) << 24) |
58 ((value & 0xFF00) << 8) |
59 ((value & 0xFF0000) >> 8) |
60 (value >> 24);
61 }
62
63 template<uint32_t N> struct SkTEndianSwap32 {
64 static const uint32_t value = ((N & 0xFF) << 24) |
65 ((N & 0xFF00) << 8) |
66 ((N & 0xFF0000) >> 8) |
67 (N >> 24);
68 };
69
70 /** Vector version of SkEndianSwap32(), which swaps the
71 bytes of each value in the array.
72 */
SkEndianSwap32s(uint32_t array[],int count)73 static inline void SkEndianSwap32s(uint32_t array[], int count) {
74 SkASSERT(count == 0 || array != nullptr);
75
76 while (--count >= 0) {
77 *array = SkEndianSwap32(*array);
78 array += 1;
79 }
80 }
81
82 /** Reverse all 8 bytes in a 64bit value.
83 e.g. 0x1122334455667788 -> 0x8877665544332211
84 */
SkEndianSwap64(uint64_t value)85 static inline uint64_t SkEndianSwap64(uint64_t value) {
86 return (((value & 0x00000000000000FFULL) << (8*7)) |
87 ((value & 0x000000000000FF00ULL) << (8*5)) |
88 ((value & 0x0000000000FF0000ULL) << (8*3)) |
89 ((value & 0x00000000FF000000ULL) << (8*1)) |
90 ((value & 0x000000FF00000000ULL) >> (8*1)) |
91 ((value & 0x0000FF0000000000ULL) >> (8*3)) |
92 ((value & 0x00FF000000000000ULL) >> (8*5)) |
93 ((value) >> (8*7)));
94 }
95 template<uint64_t N> struct SkTEndianSwap64 {
96 static const uint64_t value = (((N & 0x00000000000000FFULL) << (8*7)) |
97 ((N & 0x000000000000FF00ULL) << (8*5)) |
98 ((N & 0x0000000000FF0000ULL) << (8*3)) |
99 ((N & 0x00000000FF000000ULL) << (8*1)) |
100 ((N & 0x000000FF00000000ULL) >> (8*1)) |
101 ((N & 0x0000FF0000000000ULL) >> (8*3)) |
102 ((N & 0x00FF000000000000ULL) >> (8*5)) |
103 ((N) >> (8*7)));
104 };
105
106 /** Vector version of SkEndianSwap64(), which swaps the
107 bytes of each value in the array.
108 */
SkEndianSwap64s(uint64_t array[],int count)109 static inline void SkEndianSwap64s(uint64_t array[], int count) {
110 SkASSERT(count == 0 || array != nullptr);
111
112 while (--count >= 0) {
113 *array = SkEndianSwap64(*array);
114 array += 1;
115 }
116 }
117
118 // Static casts are used here for otherwise no-op macros to make sure they return the same type as
119 // SkEndianSwap* functions.
120 #ifdef SK_CPU_LENDIAN
121 #define SkEndian_SwapBE16(n) SkEndianSwap16(n)
122 #define SkEndian_SwapBE32(n) SkEndianSwap32(n)
123 #define SkEndian_SwapBE64(n) SkEndianSwap64(n)
124 #define SkEndian_SwapLE16(n) static_cast<uint16_t>(n)
125 #define SkEndian_SwapLE32(n) static_cast<uint32_t>(n)
126 #define SkEndian_SwapLE64(n) static_cast<uint64_t>(n)
127
128 #define SkTEndian_SwapBE16(n) SkTEndianSwap16<n>::value
129 #define SkTEndian_SwapBE32(n) SkTEndianSwap32<n>::value
130 #define SkTEndian_SwapBE64(n) SkTEndianSwap64<n>::value
131 #define SkTEndian_SwapLE16(n) (n)
132 #define SkTEndian_SwapLE32(n) (n)
133 #define SkTEndian_SwapLE64(n) (n)
134 #else // SK_CPU_BENDIAN
135 #define SkEndian_SwapBE16(n) static_cast<uint16_t>(n)
136 #define SkEndian_SwapBE32(n) static_cast<uint32_t>(n)
137 #define SkEndian_SwapBE64(n) static_cast<uint64_t>(n)
138 #define SkEndian_SwapLE16(n) SkEndianSwap16(n)
139 #define SkEndian_SwapLE32(n) SkEndianSwap32(n)
140 #define SkEndian_SwapLE64(n) SkEndianSwap64(n)
141
142 #define SkTEndian_SwapBE16(n) (n)
143 #define SkTEndian_SwapBE32(n) (n)
144 #define SkTEndian_SwapBE64(n) (n)
145 #define SkTEndian_SwapLE16(n) SkTEndianSwap16<n>::value
146 #define SkTEndian_SwapLE32(n) SkTEndianSwap32<n>::value
147 #define SkTEndian_SwapLE64(n) SkTEndianSwap64<n>::value
148 #endif
149
150 // When a bytestream is embedded in a 32-bit word, how far we need to
151 // shift the word to extract each byte from the low 8 bits by anding with 0xff.
152 #ifdef SK_CPU_LENDIAN
153 #define SkEndian_Byte0Shift 0
154 #define SkEndian_Byte1Shift 8
155 #define SkEndian_Byte2Shift 16
156 #define SkEndian_Byte3Shift 24
157 #else // SK_CPU_BENDIAN
158 #define SkEndian_Byte0Shift 24
159 #define SkEndian_Byte1Shift 16
160 #define SkEndian_Byte2Shift 8
161 #define SkEndian_Byte3Shift 0
162 #endif
163
164
165 #if defined(SK_UINT8_BITFIELD_LENDIAN) && defined(SK_UINT8_BITFIELD_BENDIAN)
166 #error "can't have both bitfield LENDIAN and BENDIAN defined"
167 #endif
168
169 #if !defined(SK_UINT8_BITFIELD_LENDIAN) && !defined(SK_UINT8_BITFIELD_BENDIAN)
170 #ifdef SK_CPU_LENDIAN
171 #define SK_UINT8_BITFIELD_LENDIAN
172 #else
173 #define SK_UINT8_BITFIELD_BENDIAN
174 #endif
175 #endif
176
177 #ifdef SK_UINT8_BITFIELD_LENDIAN
178 #define SK_UINT8_BITFIELD(f0, f1, f2, f3, f4, f5, f6, f7) \
179 SK_OT_BYTE f0 : 1; \
180 SK_OT_BYTE f1 : 1; \
181 SK_OT_BYTE f2 : 1; \
182 SK_OT_BYTE f3 : 1; \
183 SK_OT_BYTE f4 : 1; \
184 SK_OT_BYTE f5 : 1; \
185 SK_OT_BYTE f6 : 1; \
186 SK_OT_BYTE f7 : 1;
187 #else
188 #define SK_UINT8_BITFIELD(f0, f1, f2, f3, f4, f5, f6, f7) \
189 SK_OT_BYTE f7 : 1; \
190 SK_OT_BYTE f6 : 1; \
191 SK_OT_BYTE f5 : 1; \
192 SK_OT_BYTE f4 : 1; \
193 SK_OT_BYTE f3 : 1; \
194 SK_OT_BYTE f2 : 1; \
195 SK_OT_BYTE f1 : 1; \
196 SK_OT_BYTE f0 : 1;
197 #endif
198
199 #endif
200