llvm/lib/Support/LEB128.cpp

//===- LEB128.cpp - LEB128 utility functions implementation -----*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements some utility functions for encoding SLEB128 and
// ULEB128 values.
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/LEB128.h"

namespace llvm {

/// Utility function to get the size of the ULEB128-encoded value.
unsigned getULEB128Size(uint64_t Value) {
  unsigned Size = 0;
  do {
    Value >>= 7;
    Size += sizeof(int8_t);
  } while (Value);
  return Size;
}

/// Utility function to get the size of the SLEB128-encoded value.
unsigned getSLEB128Size(int64_t Value) {
  unsigned Size = 0;
  int Sign = Value >> (8 * sizeof(Value) - 1);
  bool IsMore;

  do {
    unsigned Byte = Value & 0x7f;
    Value >>= 7;
    IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
    Size += sizeof(int8_t);
  } while (IsMore);
  return Size;
}

}  // namespace llvm