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
19enum {
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.
27static 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
34uint32_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
44uint64_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
49spv_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
72bool 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