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 "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 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 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 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 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
