lib/Support/LEB128.cpp

   1 //===- LEB128.cpp - LEB128 utility functions implementation -----*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements some utility functions for encoding SLEB128 and
  10 // ULEB128 values.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Support/LEB128.h"
  15
  16 namespace llvm {
  17
  18 /// Utility function to get the size of the ULEB128-encoded value.
  19 unsigned getULEB128Size(uint64_t Value) {
  20   unsigned Size = 0;
  21   do {
  22     Value >>= 7;
  23     Size += sizeof(int8_t);
  24   } while (Value);
  25   return Size;
  26 }
  27
  28 /// Utility function to get the size of the SLEB128-encoded value.
  29 unsigned getSLEB128Size(int64_t Value) {
  30   unsigned Size = 0;
  31   int Sign = Value >> (8 * sizeof(Value) - 1);
  32   bool IsMore;
  33
  34   do {
  35     unsigned Byte = Value & 0x7f;
  36     Value >>= 7;
  37     IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
  38     Size += sizeof(int8_t);
  39   } while (IsMore);
  40   return Size;
  41 }
  42
  43 }  // namespace llvm