Merge new upstream LTS 20230125.3

1 files changed, 72 insertions, 0 deletions

diff --git a/absl/crc/internal/crc32c_inline.h b/absl/crc/internal/crc32c_inline.h
new file mode 100644
index 00000000..6236c10b
--- /dev/null
+++ b/absl/crc/internal/crc32c_inline.h
@@ -0,0 +1,72 @@
+// Copyright 2022 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_CRC_INTERNAL_CRC32C_INLINE_H_
+#define ABSL_CRC_INTERNAL_CRC32C_INLINE_H_
+
+#include <cstdint>
+
+#include "absl/base/config.h"
+#include "absl/base/internal/endian.h"
+#include "absl/crc/internal/crc32_x86_arm_combined_simd.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace crc_internal {
+
+// CRC32C implementation optimized for small inputs.
+// Either computes crc and return true, or if there is
+// no hardware support does nothing and returns false.
+inline bool ExtendCrc32cInline(uint32_t* crc, const char* p, size_t n) {
+#if defined(ABSL_CRC_INTERNAL_HAVE_ARM_SIMD) || \
+    defined(ABSL_CRC_INTERNAL_HAVE_X86_SIMD)
+  constexpr uint32_t kCrc32Xor = 0xffffffffU;
+  *crc ^= kCrc32Xor;
+  if (n & 1) {
+    *crc = CRC32_u8(*crc, static_cast<uint8_t>(*p));
+    n--;
+    p++;
+  }
+  if (n & 2) {
+    *crc = CRC32_u16(*crc, absl::little_endian::Load16(p));
+    n -= 2;
+    p += 2;
+  }
+  if (n & 4) {
+    *crc = CRC32_u32(*crc, absl::little_endian::Load32(p));
+    n -= 4;
+    p += 4;
+  }
+  while (n) {
+    *crc = CRC32_u64(*crc, absl::little_endian::Load64(p));
+    n -= 8;
+    p += 8;
+  }
+  *crc ^= kCrc32Xor;
+  return true;
+#else
+  // No hardware support, signal the need to fallback.
+  static_cast<void>(crc);
+  static_cast<void>(p);
+  static_cast<void>(n);
+  return false;
+#endif  // defined(ABSL_CRC_INTERNAL_HAVE_ARM_SIMD) ||
+        // defined(ABSL_CRC_INTERNAL_HAVE_X86_SIMD)
+}
+
+}  // namespace crc_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CRC_INTERNAL_CRC32C_INLINE_H_