From ef7aefc53bf24214f489bf9e4100bcff45f7b12a Mon Sep 17 00:00:00 2001
From: Alexey Samsonov <samsonov@google.com>
Date: Wed, 14 Aug 2013 16:03:29 +0000
Subject: [PATCH] Expose CRC-32 implementation from zlib

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188380 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Support/Compression.h    | 2 ++
 lib/Support/Compression.cpp           | 7 +++++++
 unittests/Support/CompressionTest.cpp | 6 ++++++
 3 files changed, 15 insertions(+)

diff --git a/include/llvm/Support/Compression.h b/include/llvm/Support/Compression.h
index 9b1142d035d..bef9146d07d 100644
--- a/include/llvm/Support/Compression.h
+++ b/include/llvm/Support/Compression.h
@@ -50,6 +50,8 @@ Status uncompress(StringRef InputBuffer,
                   OwningPtr<MemoryBuffer> &UncompressedBuffer,
                   size_t UncompressedSize);
 
+uint32_t crc32(StringRef Buffer);
+
 }  // End of namespace zlib
 
 } // End of namespace llvm
diff --git a/lib/Support/Compression.cpp b/lib/Support/Compression.cpp
index fd8a8743ea1..b5ddb7002ca 100644
--- a/lib/Support/Compression.cpp
+++ b/lib/Support/Compression.cpp
@@ -81,6 +81,10 @@ zlib::Status zlib::uncompress(StringRef InputBuffer,
   return Res;
 }
 
+uint32_t zlib::crc32(StringRef Buffer) {
+  return ::crc32(0, (const Bytef *)Buffer.data(), Buffer.size());
+}
+
 #else
 bool zlib::isAvailable() { return false; }
 zlib::Status zlib::compress(StringRef InputBuffer,
@@ -93,5 +97,8 @@ zlib::Status zlib::uncompress(StringRef InputBuffer,
                               size_t UncompressedSize) {
   return zlib::StatusUnsupported;
 }
+uint32_t zlib::crc32(StringRef Buffer) {
+  llvm_unreachable("zlib::crc32 is unavailable");
+}
 #endif
 
diff --git a/unittests/Support/CompressionTest.cpp b/unittests/Support/CompressionTest.cpp
index c8e2cd9f02b..c0a9adadb78 100644
--- a/unittests/Support/CompressionTest.cpp
+++ b/unittests/Support/CompressionTest.cpp
@@ -63,6 +63,12 @@ TEST(CompressionTest, Zlib) {
   TestZlibCompression(BinaryDataStr, zlib::DefaultCompression);
 }
 
+TEST(CompressionTest, ZlibCRC32) {
+  EXPECT_EQ(
+      0x414FA339U,
+      zlib::crc32(StringRef("The quick brown fox jumps over the lazy dog")));
+}
+
 #endif
 
 }
-- 
2.34.1