Move [SU]LEB128 encoding to a utility header.

These functions are very generic. There's no reason for them to
be tied to MCObjectWriter.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161545 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 58 insertions, 5 deletions

diff --git a/include/llvm/MC/MCObjectWriter.h b/include/llvm/MC/MCObjectWriter.h
index 6e44e6c..9591a00 100644
--- a/include/llvm/MC/MCObjectWriter.h
+++ b/include/llvm/MC/MCObjectWriter.h
@@ -182,11 +182,6 @@ public:
 
   /// @}
 
-  /// Utility function to encode a SLEB128 value.
-  static void EncodeSLEB128(int64_t Value, raw_ostream &OS);
-  /// Utility function to encode a ULEB128 value.
-  static void EncodeULEB128(uint64_t Value, raw_ostream &OS,
-                            unsigned Padding = 0);
 };
 
 } // End llvm namespace
diff --git a/include/llvm/Support/LEB128.h b/include/llvm/Support/LEB128.h
new file mode 100644
index 0000000..00c7eea
--- /dev/null
+++ b/include/llvm/Support/LEB128.h
@@ -0,0 +1,58 @@
+//===- llvm/Support/LEB128.h - [SU]LEB128 utility functions -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares some utility functions for encoding SLEB128 and
+// ULEB128 values.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SYSTEM_LEB128_H
+#define LLVM_SYSTEM_LEB128_H
+
+#include <llvm/Support/raw_ostream.h>
+
+namespace llvm {
+
+/// Utility function to encode a SLEB128 value.
+static inline void encodeSLEB128(int64_t Value, raw_ostream &OS) {
+  bool More;
+  do {
+    uint8_t Byte = Value & 0x7f;
+    // NOTE: this assumes that this signed shift is an arithmetic right shift.
+    Value >>= 7;
+    More = !((((Value == 0 ) && ((Byte & 0x40) == 0)) ||
+              ((Value == -1) && ((Byte & 0x40) != 0))));
+    if (More)
+      Byte |= 0x80; // Mark this byte that that more bytes will follow.
+    OS << char(Byte);
+  } while (More);
+}
+
+/// Utility function to encode a ULEB128 value.
+static inline void encodeULEB128(uint64_t Value, raw_ostream &OS,
+                                 unsigned Padding = 0) {
+  do {
+    uint8_t Byte = Value & 0x7f;
+    Value >>= 7;
+    if (Value != 0 || Padding != 0)
+      Byte |= 0x80; // Mark this byte that that more bytes will follow.
+    OS << char(Byte);
+  } while (Value != 0);
+
+  // Pad with 0x80 and emit a null byte at the end.
+  if (Padding != 0) {
+    for (; Padding != 1; --Padding)
+      OS << '\x80';
+    OS << '\x00';
+  }
+}
+
+}  // namespace llvm
+
+#endif  // LLVM_SYSTEM_LEB128_H