OutputBuffer.h revision 6b5788edb17bad161bbe7a21f38a45f92bba892f 
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 <string>
18#include <vector>
19
20namespace llvm {
21
22  class OutputBuffer {
23    /// Output buffer.
24    std::vector<unsigned char> &Output;
25
26    /// is64Bit/isLittleEndian - This information is inferred from the target
27    /// machine directly, indicating what header values and flags to set.
28    bool is64Bit, isLittleEndian;
29  public:
30    OutputBuffer(std::vector<unsigned char> &Out,
31                 bool is64bit, bool le)
32      : Output(Out), is64Bit(is64bit), isLittleEndian(le) {}
33
34    // align - Emit padding into the file until the current output position is
35    // aligned to the specified power of two boundary.
36    void align(unsigned Boundary) {
37      assert(Boundary && (Boundary & (Boundary - 1)) == 0 &&
38             "Must align to 2^k boundary");
39      size_t Size = Output.size();
40
41      if (Size & (Boundary - 1)) {
42        // Add padding to get alignment to the correct place.
43        size_t Pad = Boundary - (Size & (Boundary - 1));
44        Output.resize(Size + Pad);
45      }
46    }
47
48    //===------------------------------------------------------------------===//
49    // Out Functions - Output the specified value to the data buffer.
50
51    void outbyte(unsigned char X) {
52      Output.push_back(X);
53    }
54    void outhalf(unsigned short X) {
55      if (isLittleEndian) {
56        Output.push_back(X & 255);
57        Output.push_back(X >> 8);
58      } else {
59        Output.push_back(X >> 8);
60        Output.push_back(X & 255);
61      }
62    }
63    void outword(unsigned X) {
64      if (isLittleEndian) {
65        Output.push_back((X >>  0) & 255);
66        Output.push_back((X >>  8) & 255);
67        Output.push_back((X >> 16) & 255);
68        Output.push_back((X >> 24) & 255);
69      } else {
70        Output.push_back((X >> 24) & 255);
71        Output.push_back((X >> 16) & 255);
72        Output.push_back((X >>  8) & 255);
73        Output.push_back((X >>  0) & 255);
74      }
75    }
76    void outxword(uint64_t X) {
77      if (isLittleEndian) {
78        Output.push_back(unsigned(X >>  0) & 255);
79        Output.push_back(unsigned(X >>  8) & 255);
80        Output.push_back(unsigned(X >> 16) & 255);
81        Output.push_back(unsigned(X >> 24) & 255);
82        Output.push_back(unsigned(X >> 32) & 255);
83        Output.push_back(unsigned(X >> 40) & 255);
84        Output.push_back(unsigned(X >> 48) & 255);
85        Output.push_back(unsigned(X >> 56) & 255);
86      } else {
87        Output.push_back(unsigned(X >> 56) & 255);
88        Output.push_back(unsigned(X >> 48) & 255);
89        Output.push_back(unsigned(X >> 40) & 255);
90        Output.push_back(unsigned(X >> 32) & 255);
91        Output.push_back(unsigned(X >> 24) & 255);
92        Output.push_back(unsigned(X >> 16) & 255);
93        Output.push_back(unsigned(X >>  8) & 255);
94        Output.push_back(unsigned(X >>  0) & 255);
95      }
96    }
97    void outaddr32(unsigned X) {
98      outword(X);
99    }
100    void outaddr64(uint64_t X) {
101      outxword(X);
102    }
103    void outaddr(uint64_t X) {
104      if (!is64Bit)
105        outword((unsigned)X);
106      else
107        outxword(X);
108    }
109    void outstring(const std::string &S, unsigned Length) {
110      unsigned len_to_copy = static_cast<unsigned>(S.length()) < Length
111        ? static_cast<unsigned>(S.length()) : Length;
112      unsigned len_to_fill = static_cast<unsigned>(S.length()) < Length
113        ? Length - static_cast<unsigned>(S.length()) : 0;
114
115      for (unsigned i = 0; i < len_to_copy; ++i)
116        outbyte(S[i]);
117
118      for (unsigned i = 0; i < len_to_fill; ++i)
119        outbyte(0);
120    }
121
122    //===------------------------------------------------------------------===//
123    // Fix Functions - Replace an existing entry at an offset.
124
125    void fixhalf(unsigned short X, unsigned Offset) {
126      unsigned char *P = &Output[Offset];
127      P[0] = (X >> (isLittleEndian ?  0 : 8)) & 255;
128      P[1] = (X >> (isLittleEndian ?  8 : 0)) & 255;
129    }
130    void fixword(unsigned X, unsigned Offset) {
131      unsigned char *P = &Output[Offset];
132      P[0] = (X >> (isLittleEndian ?  0 : 24)) & 255;
133      P[1] = (X >> (isLittleEndian ?  8 : 16)) & 255;
134      P[2] = (X >> (isLittleEndian ? 16 :  8)) & 255;
135      P[3] = (X >> (isLittleEndian ? 24 :  0)) & 255;
136    }
137    void fixxword(uint64_t X, unsigned Offset) {
138      unsigned char *P = &Output[Offset];
139      P[0] = (X >> (isLittleEndian ?  0 : 56)) & 255;
140      P[1] = (X >> (isLittleEndian ?  8 : 48)) & 255;
141      P[2] = (X >> (isLittleEndian ? 16 : 40)) & 255;
142      P[3] = (X >> (isLittleEndian ? 24 : 32)) & 255;
143      P[4] = (X >> (isLittleEndian ? 32 : 24)) & 255;
144      P[5] = (X >> (isLittleEndian ? 40 : 16)) & 255;
145      P[6] = (X >> (isLittleEndian ? 48 :  8)) & 255;
146      P[7] = (X >> (isLittleEndian ? 56 :  0)) & 255;
147    }
148    void fixaddr(uint64_t X, unsigned Offset) {
149      if (!is64Bit)
150        fixword((unsigned)X, Offset);
151      else
152        fixxword(X, Offset);
153    }
154
155    unsigned char &operator[](unsigned Index) {
156      return Output[Index];
157    }
158    const unsigned char &operator[](unsigned Index) const {
159      return Output[Index];
160    }
161  };
162
163} // end llvm namespace
164
165#endif // LLVM_SUPPORT_OUTPUTBUFFER_H
166