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| author | Stephen Hines <srhines@google.com> | 2012-08-23 19:08:53 -0700 |
|---|---|---|
| committer | Stephen Hines <srhines@google.com> | 2012-08-23 19:08:53 -0700 |
| commit | 31675153bd2d7617db8cb6aeb58054934c7b9f73 (patch) | |
| tree | c1970fcebc736d4f731db0559a79a7ac5cb0f8bf /include/llvm/Support/LEB128.h | |
| parent | 416bb6a168a9316547db6ce3909c515f70a84f52 (diff) | |
| parent | 75dd7f0c4a2b3fb9e9d4d5a0517591810c57ed92 (diff) | |
| download | external_llvm-31675153bd2d7617db8cb6aeb58054934c7b9f73.zip external_llvm-31675153bd2d7617db8cb6aeb58054934c7b9f73.tar.gz external_llvm-31675153bd2d7617db8cb6aeb58054934c7b9f73.tar.bz2 | |
Merge branch 'upstream' into merge_2
Conflicts:
lib/Target/ARM/ARMCodeEmitter.cpp
Change-Id: I6702d340c733e9721499b5d85b13b96ad9c14eb5
Diffstat (limited to 'include/llvm/Support/LEB128.h')
| -rw-r--r-- | include/llvm/Support/LEB128.h | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/include/llvm/Support/LEB128.h b/include/llvm/Support/LEB128.h new file mode 100644 index 0000000..410edd4 --- /dev/null +++ b/include/llvm/Support/LEB128.h @@ -0,0 +1,95 @@ +//===- 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 to an output stream. +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 to an output stream. +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'; + } +} + +/// Utility function to encode a ULEB128 value to a buffer. Returns +/// the length in bytes of the encoded value. +static inline unsigned encodeULEB128(uint64_t Value, uint8_t *p, + unsigned Padding = 0) { + uint8_t *orig_p = p; + do { + uint8_t Byte = Value & 0x7f; + Value >>= 7; + if (Value != 0 || Padding != 0) + Byte |= 0x80; // Mark this byte that that more bytes will follow. + *p++ = Byte; + } while (Value != 0); + + // Pad with 0x80 and emit a null byte at the end. + if (Padding != 0) { + for (; Padding != 1; --Padding) + *p++ = '\x80'; + *p++ = '\x00'; + } + return (unsigned)(p - orig_p); +} + + +/// Utility function to decode a ULEB128 value. +static inline uint64_t decodeULEB128(const uint8_t *p, unsigned *n = 0) { + const uint8_t *orig_p = p; + uint64_t Value = 0; + unsigned Shift = 0; + do { + Value += (*p & 0x7f) << Shift; + Shift += 7; + } while (*p++ >= 128); + if (n) + *n = (unsigned)(p - orig_p); + return Value; +} + +} // namespace llvm + +#endif // LLVM_SYSTEM_LEB128_H |
