Squashed 'src/crc32c/' content from commit 224988680f7673cd7c769963d4035cb315aa3388

git-subtree-dir: src/crc32c
git-subtree-split: 224988680f7673cd7c769963d4035cb315aa3388

1 files changed, 53 insertions, 0 deletions

diff --git a/src/crc32c_read_le.h b/src/crc32c_read_le.h
new file mode 100644
index 0000000000..3bd45fe3aa
--- /dev/null
+++ b/src/crc32c_read_le.h
@@ -0,0 +1,53 @@
+// Copyright 2017 The CRC32C Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef CRC32C_CRC32C_READ_LE_H_
+#define CRC32C_CRC32C_READ_LE_H_
+
+#include <cstdint>
+#include <cstring>
+
+#ifdef CRC32C_HAVE_CONFIG_H
+#include "crc32c/crc32c_config.h"
+#endif
+
+namespace crc32c {
+
+// Reads a little-endian 32-bit integer from a 32-bit-aligned buffer.
+inline uint32_t ReadUint32LE(const uint8_t* buffer) {
+#if 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));
+#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
+}
+
+// Reads a little-endian 64-bit integer from a 64-bit-aligned buffer.
+inline uint64_t ReadUint64LE(const uint8_t* buffer) {
+#if 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) |
+          (static_cast<uint32_t>(static_cast<uint8_t>(buffer[4])) << 32) |
+          (static_cast<uint32_t>(static_cast<uint8_t>(buffer[5])) << 40) |
+          (static_cast<uint32_t>(static_cast<uint8_t>(buffer[6])) << 48) |
+          (static_cast<uint32_t>(static_cast<uint8_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
+}
+
+}  // namespace crc32c
+
+#endif  // CRC32C_CRC32C_READ_LE_H_