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272 lines
8.3 KiB
C++
272 lines
8.3 KiB
C++
//===-- llvm/Bytecode/Primitives.h - Bytecode file format prims --*- C++ -*--=//
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//
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// This header defines some basic functions for reading and writing basic
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// primitive types to a bytecode stream.
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//
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// Using the routines defined in this file does not require linking to any
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// libraries, as all of the services are small self contained units that are to
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// be inlined as neccesary.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_BYTECODE_PRIMITIVES_H
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#define LLVM_BYTECODE_PRIMITIVES_H
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#include "Support/DataTypes.h"
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#include <string>
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#include <deque>
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//===----------------------------------------------------------------------===//
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// Reading Primitives
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//===----------------------------------------------------------------------===//
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static inline bool read(const unsigned char *&Buf, const unsigned char *EndBuf,
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unsigned &Result) {
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if (Buf+4 > EndBuf) return true;
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#ifdef LITTLE_ENDIAN
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Result = *(unsigned*)Buf;
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#else
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Result = Buf[0] | (Buf[1] << 8) | (Buf[2] << 16) | (Buf[3] << 24);
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#endif
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Buf += 4;
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return false;
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}
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static inline bool read(const unsigned char *&Buf, const unsigned char *EndBuf,
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uint64_t &Result) {
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if (Buf+8 > EndBuf) return true;
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#ifdef LITTLE_ENDIAN
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Result = *(uint64_t*)Buf;
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#else
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Result = Buf[0] | (Buf[1] << 8) | (Buf[2] << 16) | (Buf[3] << 24) |
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((uint64_t)(Buf[4] | (Buf[5] << 8) | (Buf[6] << 16) | (Buf[7] << 24)) <<32);
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#endif
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Buf += 8;
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return false;
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}
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static inline bool read(const unsigned char *&Buf, const unsigned char *EndBuf,
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int &Result) {
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return read(Buf, EndBuf, (unsigned &)Result);
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}
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static inline bool read(const unsigned char *&Buf, const unsigned char *EndBuf,
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int64_t &Result) {
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return read(Buf, EndBuf, (uint64_t &)Result);
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}
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// read_vbr - Read an unsigned integer encoded in variable bitrate format.
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//
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static inline bool read_vbr(const unsigned char *&Buf,
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const unsigned char *EndBuf, unsigned &Result) {
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unsigned Shift = Result = 0;
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do {
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Result |= (unsigned)((*Buf++) & 0x7F) << Shift;
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Shift += 7;
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} while (Buf[-1] & 0x80 && Buf < EndBuf);
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return Buf > EndBuf;
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}
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static inline bool read_vbr(const unsigned char *&Buf,
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const unsigned char *EndBuf, uint64_t &Result) {
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unsigned Shift = 0; Result = 0;
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do {
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Result |= (uint64_t)((*Buf++) & 0x7F) << Shift;
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Shift += 7;
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} while (Buf[-1] & 0x80 && Buf < EndBuf);
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return Buf > EndBuf;
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}
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// read_vbr (signed) - Read a signed number stored in sign-magnitude format
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static inline bool read_vbr(const unsigned char *&Buf,
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const unsigned char *EndBuf, int &Result) {
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unsigned R;
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if (read_vbr(Buf, EndBuf, R)) return true;
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if (R & 1)
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Result = -(int)(R >> 1);
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else
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Result = (int)(R >> 1);
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return false;
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}
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static inline bool read_vbr(const unsigned char *&Buf,
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const unsigned char *EndBuf, int64_t &Result) {
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uint64_t R;
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if (read_vbr(Buf, EndBuf, R)) return true;
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if (R & 1)
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Result = -(int64_t)(R >> 1);
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else
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Result = (int64_t)(R >> 1);
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return false;
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}
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// align32 - Round up to multiple of 32 bits...
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static inline bool align32(const unsigned char *&Buf,
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const unsigned char *EndBuf) {
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Buf = (const unsigned char *)((unsigned long)(Buf+3) & (~3UL));
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return Buf > EndBuf;
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}
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static inline bool read(const unsigned char *&Buf, const unsigned char *EndBuf,
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std::string &Result, bool Aligned = true) {
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unsigned Size;
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if (read_vbr(Buf, EndBuf, Size)) return true; // Failure reading size?
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if (Buf+Size > EndBuf) return true; // Size invalid?
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Result = std::string((char*)Buf, Size);
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Buf += Size;
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if (Aligned) // If we should stay aligned do so...
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if (align32(Buf, EndBuf)) return true; // Failure aligning?
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return false;
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}
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static inline bool input_data(const unsigned char *&Buf,
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const unsigned char *EndBuf,
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void *Ptr, void *End, bool Align = false) {
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unsigned char *Start = (unsigned char *)Ptr;
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unsigned Amount = (unsigned char *)End - Start;
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if (Buf+Amount > EndBuf) return true;
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#ifdef LITTLE_ENDIAN
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std::copy(Buf, Buf+Amount, Start);
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Buf += Amount;
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#else
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unsigned char *E = (unsigned char *)End;
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while (Ptr != E)
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*--E = *Buf++;
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#endif
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if (Align) return align32(Buf, EndBuf);
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return false;
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}
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//===----------------------------------------------------------------------===//
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// Writing Primitives
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//===----------------------------------------------------------------------===//
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// output - If a position is specified, it must be in the valid portion of the
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// string... note that this should be inlined always so only the relevant IF
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// body should be included...
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//
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static inline void output(unsigned i, std::deque<unsigned char> &Out,
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int pos = -1) {
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#ifdef LITTLE_ENDIAN
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if (pos == -1)
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Out.insert(Out.end(), (unsigned char*)&i, (unsigned char*)&i+4);
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else
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// This cannot use block copy because deques are not guaranteed contiguous!
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std::copy((unsigned char*)&i, 4+(unsigned char*)&i, Out.begin()+pos);
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#else
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if (pos == -1) { // Be endian clean, little endian is our friend
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Out.push_back((unsigned char)i);
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Out.push_back((unsigned char)(i >> 8));
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Out.push_back((unsigned char)(i >> 16));
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Out.push_back((unsigned char)(i >> 24));
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} else {
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Out[pos ] = (unsigned char)i;
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Out[pos+1] = (unsigned char)(i >> 8);
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Out[pos+2] = (unsigned char)(i >> 16);
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Out[pos+3] = (unsigned char)(i >> 24);
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}
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#endif
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}
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static inline void output(int i, std::deque<unsigned char> &Out) {
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output((unsigned)i, Out);
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}
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// output_vbr - Output an unsigned value, by using the least number of bytes
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// possible. This is useful because many of our "infinite" values are really
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// very small most of the time... but can be large a few times...
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//
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// Data format used: If you read a byte with the night bit set, use the low
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// seven bits as data and then read another byte...
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//
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// Note that using this may cause the output buffer to become unaligned...
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//
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static inline void output_vbr(uint64_t i, std::deque<unsigned char> &out) {
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while (1) {
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if (i < 0x80) { // done?
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out.push_back((unsigned char)i); // We know the high bit is clear...
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return;
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}
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// Nope, we are bigger than a character, output the next 7 bits and set the
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// high bit to say that there is more coming...
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out.push_back(0x80 | (i & 0x7F));
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i >>= 7; // Shift out 7 bits now...
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}
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}
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static inline void output_vbr(unsigned i, std::deque<unsigned char> &out) {
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while (1) {
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if (i < 0x80) { // done?
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out.push_back((unsigned char)i); // We know the high bit is clear...
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return;
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}
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// Nope, we are bigger than a character, output the next 7 bits and set the
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// high bit to say that there is more coming...
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out.push_back(0x80 | (i & 0x7F));
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i >>= 7; // Shift out 7 bits now...
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}
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}
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static inline void output_vbr(int64_t i, std::deque<unsigned char> &out) {
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if (i < 0)
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output_vbr(((uint64_t)(-i) << 1) | 1, out); // Set low order sign bit...
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else
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output_vbr((uint64_t)i << 1, out); // Low order bit is clear.
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}
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static inline void output_vbr(int i, std::deque<unsigned char> &out) {
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if (i < 0)
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output_vbr(((unsigned)(-i) << 1) | 1, out); // Set low order sign bit...
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else
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output_vbr((unsigned)i << 1, out); // Low order bit is clear.
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}
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// align32 - emit the minimal number of bytes that will bring us to 32 bit
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// alignment...
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//
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static inline void align32(std::deque<unsigned char> &Out) {
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int NumPads = (4-(Out.size() & 3)) & 3; // Bytes to get padding to 32 bits
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while (NumPads--) Out.push_back((unsigned char)0xAB);
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}
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static inline void output(const std::string &s, std::deque<unsigned char> &Out,
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bool Aligned = true) {
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unsigned Len = s.length();
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output_vbr(Len, Out); // Strings may have an arbitrary length...
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Out.insert(Out.end(), s.begin(), s.end());
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if (Aligned)
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align32(Out); // Make sure we are now aligned...
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}
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static inline void output_data(void *Ptr, void *End,
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std::deque<unsigned char> &Out,
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bool Align = false) {
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#ifdef LITTLE_ENDIAN
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Out.insert(Out.end(), (unsigned char*)Ptr, (unsigned char*)End);
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#else
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unsigned char *E = (unsigned char *)End;
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while (Ptr != E)
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Out.push_back(*--E);
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#endif
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if (Align) align32(Out);
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}
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#endif
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