1 // Copyright (c) 2015-2016 The Khronos Group Inc.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "source/spirv_endian.h"
16
17 #include <cstring>
18
19 enum {
20 I32_ENDIAN_LITTLE = 0x03020100ul,
21 I32_ENDIAN_BIG = 0x00010203ul,
22 };
23
24 // This constant value allows the detection of the host machine's endianness.
25 // Accessing it through the "value" member is valid due to C++11 section 3.10
26 // paragraph 10.
27 static const union {
28 unsigned char bytes[4];
29 uint32_t value;
30 } o32_host_order = {{0, 1, 2, 3}};
31
32 #define I32_ENDIAN_HOST (o32_host_order.value)
33
spvFixWord(const uint32_t word,const spv_endianness_t endian)34 uint32_t spvFixWord(const uint32_t word, const spv_endianness_t endian) {
35 if ((SPV_ENDIANNESS_LITTLE == endian && I32_ENDIAN_HOST == I32_ENDIAN_BIG) ||
36 (SPV_ENDIANNESS_BIG == endian && I32_ENDIAN_HOST == I32_ENDIAN_LITTLE)) {
37 return (word & 0x000000ff) << 24 | (word & 0x0000ff00) << 8 |
38 (word & 0x00ff0000) >> 8 | (word & 0xff000000) >> 24;
39 }
40
41 return word;
42 }
43
spvFixDoubleWord(const uint32_t low,const uint32_t high,const spv_endianness_t endian)44 uint64_t spvFixDoubleWord(const uint32_t low, const uint32_t high,
45 const spv_endianness_t endian) {
46 return (uint64_t(spvFixWord(high, endian)) << 32) | spvFixWord(low, endian);
47 }
48
spvBinaryEndianness(spv_const_binary binary,spv_endianness_t * pEndian)49 spv_result_t spvBinaryEndianness(spv_const_binary binary,
50 spv_endianness_t* pEndian) {
51 if (!binary->code || !binary->wordCount) return SPV_ERROR_INVALID_BINARY;
52 if (!pEndian) return SPV_ERROR_INVALID_POINTER;
53
54 uint8_t bytes[4];
55 memcpy(bytes, binary->code, sizeof(uint32_t));
56
57 if (0x03 == bytes[0] && 0x02 == bytes[1] && 0x23 == bytes[2] &&
58 0x07 == bytes[3]) {
59 *pEndian = SPV_ENDIANNESS_LITTLE;
60 return SPV_SUCCESS;
61 }
62
63 if (0x07 == bytes[0] && 0x23 == bytes[1] && 0x02 == bytes[2] &&
64 0x03 == bytes[3]) {
65 *pEndian = SPV_ENDIANNESS_BIG;
66 return SPV_SUCCESS;
67 }
68
69 return SPV_ERROR_INVALID_BINARY;
70 }
71
spvIsHostEndian(spv_endianness_t endian)72 bool spvIsHostEndian(spv_endianness_t endian) {
73 return ((SPV_ENDIANNESS_LITTLE == endian) &&
74 (I32_ENDIAN_LITTLE == I32_ENDIAN_HOST)) ||
75 ((SPV_ENDIANNESS_BIG == endian) &&
76 (I32_ENDIAN_BIG == I32_ENDIAN_HOST));
77 }
78