src/llvm/include/llvm/Support/OutputBuffer.h

   1 //=== OutputBuffer.h - Output Buffer ----------------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Methods to output values to a data buffer.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_SUPPORT_OUTPUTBUFFER_H
  15 #define LLVM_SUPPORT_OUTPUTBUFFER_H
  16
  17 #include <cassert>
  18 #include <string>
  19 #include <vector>
  20
  21 namespace llvm {
  22
  23   class OutputBuffer {
  24     /// Output buffer.
  25     std::vector<unsigned char> &Output;
  26
  27     /// is64Bit/isLittleEndian - This information is inferred from the target
  28     /// machine directly, indicating what header values and flags to set.
  29     bool is64Bit, isLittleEndian;
  30   public:
  31     OutputBuffer(std::vector<unsigned char> &Out,
  32                  bool is64bit, bool le)
  33       : Output(Out), is64Bit(is64bit), isLittleEndian(le) {}
  34
  35     // align - Emit padding into the file until the current output position is
  36     // aligned to the specified power of two boundary.
  37     void align(unsigned Boundary) {
  38       assert(Boundary && (Boundary & (Boundary - 1)) == 0 &&
  39              "Must align to 2^k boundary");
  40       size_t Size = Output.size();
  41
  42       if (Size & (Boundary - 1)) {
  43         // Add padding to get alignment to the correct place.
  44         size_t Pad = Boundary - (Size & (Boundary - 1));
  45         Output.resize(Size + Pad);
  46       }
  47     }
  48
  49     //===------------------------------------------------------------------===//
  50     // Out Functions - Output the specified value to the data buffer.
  51
  52     void outbyte(unsigned char X) {
  53       Output.push_back(X);
  54     }
  55     void outhalf(unsigned short X) {
  56       if (isLittleEndian) {
  57         Output.push_back(X & 255);
  58         Output.push_back(X >> 8);
  59       } else {
  60         Output.push_back(X >> 8);
  61         Output.push_back(X & 255);
  62       }
  63     }
  64     void outword(unsigned X) {
  65       if (isLittleEndian) {
  66         Output.push_back((X >>  0) & 255);
  67         Output.push_back((X >>  8) & 255);
  68         Output.push_back((X >> 16) & 255);
  69         Output.push_back((X >> 24) & 255);
  70       } else {
  71         Output.push_back((X >> 24) & 255);
  72         Output.push_back((X >> 16) & 255);
  73         Output.push_back((X >>  8) & 255);
  74         Output.push_back((X >>  0) & 255);
  75       }
  76     }
  77     void outxword(uint64_t X) {
  78       if (isLittleEndian) {
  79         Output.push_back(unsigned(X >>  0) & 255);
  80         Output.push_back(unsigned(X >>  8) & 255);
  81         Output.push_back(unsigned(X >> 16) & 255);
  82         Output.push_back(unsigned(X >> 24) & 255);
  83         Output.push_back(unsigned(X >> 32) & 255);
  84         Output.push_back(unsigned(X >> 40) & 255);
  85         Output.push_back(unsigned(X >> 48) & 255);
  86         Output.push_back(unsigned(X >> 56) & 255);
  87       } else {
  88         Output.push_back(unsigned(X >> 56) & 255);
  89         Output.push_back(unsigned(X >> 48) & 255);
  90         Output.push_back(unsigned(X >> 40) & 255);
  91         Output.push_back(unsigned(X >> 32) & 255);
  92         Output.push_back(unsigned(X >> 24) & 255);
  93         Output.push_back(unsigned(X >> 16) & 255);
  94         Output.push_back(unsigned(X >>  8) & 255);
  95         Output.push_back(unsigned(X >>  0) & 255);
  96       }
  97     }
  98     void outaddr32(unsigned X) {
  99       outword(X);
 100     }
 101     void outaddr64(uint64_t X) {
 102       outxword(X);
 103     }
 104     void outaddr(uint64_t X) {
 105       if (!is64Bit)
 106         outword((unsigned)X);
 107       else
 108         outxword(X);
 109     }
 110     void outstring(const std::string &S, unsigned Length) {
 111       unsigned len_to_copy = static_cast<unsigned>(S.length()) < Length
 112         ? static_cast<unsigned>(S.length()) : Length;
 113       unsigned len_to_fill = static_cast<unsigned>(S.length()) < Length
 114         ? Length - static_cast<unsigned>(S.length()) : 0;
 115
 116       for (unsigned i = 0; i < len_to_copy; ++i)
 117         outbyte(S[i]);
 118
 119       for (unsigned i = 0; i < len_to_fill; ++i)
 120         outbyte(0);
 121     }
 122
 123     //===------------------------------------------------------------------===//
 124     // Fix Functions - Replace an existing entry at an offset.
 125
 126     void fixhalf(unsigned short X, unsigned Offset) {
 127       unsigned char *P = &Output[Offset];
 128       P[0] = (X >> (isLittleEndian ?  0 : 8)) & 255;
 129       P[1] = (X >> (isLittleEndian ?  8 : 0)) & 255;
 130     }
 131     void fixword(unsigned X, unsigned Offset) {
 132       unsigned char *P = &Output[Offset];
 133       P[0] = (X >> (isLittleEndian ?  0 : 24)) & 255;
 134       P[1] = (X >> (isLittleEndian ?  8 : 16)) & 255;
 135       P[2] = (X >> (isLittleEndian ? 16 :  8)) & 255;
 136       P[3] = (X >> (isLittleEndian ? 24 :  0)) & 255;
 137     }
 138     void fixxword(uint64_t X, unsigned Offset) {
 139       unsigned char *P = &Output[Offset];
 140       P[0] = (X >> (isLittleEndian ?  0 : 56)) & 255;
 141       P[1] = (X >> (isLittleEndian ?  8 : 48)) & 255;
 142       P[2] = (X >> (isLittleEndian ? 16 : 40)) & 255;
 143       P[3] = (X >> (isLittleEndian ? 24 : 32)) & 255;
 144       P[4] = (X >> (isLittleEndian ? 32 : 24)) & 255;
 145       P[5] = (X >> (isLittleEndian ? 40 : 16)) & 255;
 146       P[6] = (X >> (isLittleEndian ? 48 :  8)) & 255;
 147       P[7] = (X >> (isLittleEndian ? 56 :  0)) & 255;
 148     }
 149     void fixaddr(uint64_t X, unsigned Offset) {
 150       if (!is64Bit)
 151         fixword((unsigned)X, Offset);
 152       else
 153         fixxword(X, Offset);
 154     }
 155
 156     unsigned char &operator[](unsigned Index) {
 157       return Output[Index];
 158     }
 159     const unsigned char &operator[](unsigned Index) const {
 160       return Output[Index];
 161     }
 162   };
 163
 164 } // end llvm namespace
 165
 166 #endif // LLVM_SUPPORT_OUTPUTBUFFER_H