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build: Drop endianess workaround #64

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build: Drop endianess workaround #64

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3 changes: 0 additions & 3 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -69,9 +69,6 @@ option(CRC32C_BUILD_BENCHMARKS "Build CRC32C's benchmarks" ON)
option(CRC32C_USE_GLOG "Build CRC32C's tests with Google Logging" ON)
option(CRC32C_INSTALL "Install CRC32C's header and library" ON)

include(TestBigEndian)
test_big_endian(BYTE_ORDER_BIG_ENDIAN)

include(CheckCXXCompilerFlag)
# Used by glog.
check_cxx_compiler_flag(-Wno-deprecated CRC32C_HAVE_NO_DEPRECATED)
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3 changes: 0 additions & 3 deletions src/crc32c_config.h.in
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Expand Up @@ -5,9 +5,6 @@
#ifndef CRC32C_CRC32C_CONFIG_H_
#define CRC32C_CRC32C_CONFIG_H_

// Define to 1 if building for a big-endian platform.
#cmakedefine01 BYTE_ORDER_BIG_ENDIAN

// Define to 1 if the compiler has the __builtin_prefetch intrinsic.
#cmakedefine01 HAVE_BUILTIN_PREFETCH

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44 changes: 14 additions & 30 deletions src/crc32c_read_le.h
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Expand Up @@ -8,48 +8,32 @@
#include <cstdint>
#include <cstring>

#include "crc32c/crc32c_config.h"

namespace crc32c {

// Reads a little-endian 16-bit integer from bytes, not necessarily aligned.
inline uint16_t ReadUint16LE(const uint8_t* buffer) {
#if BYTE_ORDER_BIG_ENDIAN
return ((uint16_t{buffer[0]}) | (uint16_t{buffer[1]} << 8));
#else // !BYTE_ORDER_BIG_ENDIAN
uint16_t result;
// This should be optimized to a single instruction.
std::memcpy(&result, buffer, sizeof(result));
return result;
#endif // BYTE_ORDER_BIG_ENDIAN
return ((static_cast<uint16_t>(static_cast<uint8_t>(buffer[0]))) |
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buffer is of type const uint8_t*.
buffer[0] is of type uint8_t.
Hence, the explicit conversion static_cast<uint8_t>(buffer[0]) is redundant.

(static_cast<uint16_t>(static_cast<uint8_t>(buffer[1])) << 8));
}

// Reads a little-endian 32-bit integer from bytes, not necessarily aligned.
inline uint32_t ReadUint32LE(const uint8_t* buffer) {
#if BYTE_ORDER_BIG_ENDIAN
return ((uint32_t{buffer[0]}) | (uint32_t{buffer[1]} << 8) |
(uint32_t{buffer[2]} << 16) | (uint32_t{buffer[3]} << 24));
#else // !BYTE_ORDER_BIG_ENDIAN
uint32_t result;
// This should be optimized to a single instruction.
std::memcpy(&result, buffer, sizeof(result));
return result;
#endif // BYTE_ORDER_BIG_ENDIAN
return ((static_cast<uint32_t>(static_cast<uint8_t>(buffer[0]))) |
(static_cast<uint32_t>(static_cast<uint8_t>(buffer[1])) << 8) |
(static_cast<uint32_t>(static_cast<uint8_t>(buffer[2])) << 16) |
(static_cast<uint32_t>(static_cast<uint8_t>(buffer[3])) << 24));
}

// Reads a little-endian 64-bit integer from bytes, not necessarily aligned.
inline uint64_t ReadUint64LE(const uint8_t* buffer) {
#if BYTE_ORDER_BIG_ENDIAN
return ((uint64_t{buffer[0]}) | (uint64_t{buffer[1]} << 8) |
(uint64_t{buffer[2]} << 16) | (uint64_t{buffer[3]} << 24) |
(uint64_t{buffer[4]} << 32) | (uint64_t{buffer[5]} << 40) |
(uint64_t{buffer[6]} << 48) | (uint64_t{buffer[7]} << 56));
#else // !BYTE_ORDER_BIG_ENDIAN
uint64_t result;
// This should be optimized to a single instruction.
std::memcpy(&result, buffer, sizeof(result));
return result;
#endif // BYTE_ORDER_BIG_ENDIAN
return ((static_cast<uint64_t>(static_cast<uint8_t>(buffer[0]))) |
(static_cast<uint64_t>(static_cast<uint8_t>(buffer[1])) << 8) |
(static_cast<uint64_t>(static_cast<uint8_t>(buffer[2])) << 16) |
(static_cast<uint64_t>(static_cast<uint8_t>(buffer[3])) << 24) |
(static_cast<uint64_t>(static_cast<uint8_t>(buffer[4])) << 32) |
(static_cast<uint64_t>(static_cast<uint8_t>(buffer[5])) << 40) |
(static_cast<uint64_t>(static_cast<uint8_t>(buffer[6])) << 48) |
(static_cast<uint64_t>(static_cast<uint8_t>(buffer[7])) << 56));
}

} // namespace crc32c
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