mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-18 12:29:21 +00:00
distinguished. Tidy up documentation. Thanks, Chris. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16652 91177308-0d34-0410-b5e6-96231b3b80d8
102 lines
4.9 KiB
C++
102 lines
4.9 KiB
C++
//===- llvm/Support/Compressor.h --------------------------------*- C++ -*-===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file was developed by Reid Spencer and is distributed under the
|
|
// University of Illinois Open Source License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file declares the llvm::Compressor class.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_SUPPORT_COMPRESSOR_H
|
|
#define LLVM_SUPPORT_COMPRESSOR_H
|
|
|
|
#include "llvm/Support/DataTypes.h"
|
|
|
|
namespace llvm {
|
|
|
|
/// This class provides an abstraction for compressing a block of memory using
|
|
/// a standard compression utility such as bzip2 or libz. This interface
|
|
/// allows us to abstract the notion of compression and deal with alternate
|
|
/// compression scheme availability depending on the configured platform. This
|
|
/// facility will always favor a bzip2 implementation if its available.
|
|
/// Otherwise, libz will be used if it is available. If neither zlib nor bzip2
|
|
/// are available, a very simple algorithm provided by the Compressor class
|
|
/// will be used. The type of compression used can be determined by inspecting
|
|
/// the first byte of the compressed output. ASCII values '0', '1', and '2',
|
|
/// denote the compression type as given in the Algorithm enumeration below.
|
|
/// The Compressor is intended for use with memory mapped files where the
|
|
/// entire data block to be compressed or decompressed is available in
|
|
/// memory. However, output can be gathered in repeated calls to a callback.
|
|
/// @since 1.4
|
|
/// @brief An abstraction for memory to memory data (de)compression
|
|
class Compressor {
|
|
/// @name Types
|
|
/// @{
|
|
public:
|
|
enum Algorithm {
|
|
COMP_TYPE_SIMPLE = '0', ///< Use simple but ubiquitous algorithm
|
|
COMP_TYPE_ZLIB = '1', ///< Use zlib algorithm, if available
|
|
COMP_TYPE_BZIP2 = '2', ///< Use bzip2 algorithm (preferred)
|
|
};
|
|
|
|
/// A callback function type used by the Compressor to get the next chunk
|
|
/// of data to which (de)compressed output will be written. This function
|
|
/// must be written by the caller to provide the buffering of the output
|
|
/// data.
|
|
/// @returns 0 for success, 1 for failure
|
|
/// @throws nothing
|
|
/// @brief Output callback function type
|
|
typedef unsigned (OutputDataCallback)(char*& buffer, unsigned& size,
|
|
void* context);
|
|
|
|
/// @}
|
|
/// @name Methods
|
|
/// @{
|
|
public:
|
|
/// This function does the compression work. The block of memory starting
|
|
/// at \p in and extending for \p size bytes is compressed. The compressed
|
|
/// output is written to memory blocks returned by the \p cb callback. The
|
|
/// caller must provide an implementation of the OutputDataCallback
|
|
/// function type and provide its address as \p cb. Note that the callback
|
|
/// function will be called as many times as necessary to complete the
|
|
/// compression of the \p in block but that the total size will generally
|
|
/// be less than \p size. It is a good idea to provide as large a value to
|
|
/// the callback's \p size parameter as possible so that fewer calls to
|
|
/// the callback are made. The \p hint parameter tells the function which
|
|
/// kind of compression to start with. However, if its not available on
|
|
/// the platform, the algorithm "falls back" from bzip2 -> zlib -> simple.
|
|
/// @throws std::string if an error occurs
|
|
/// @returns the total size of the compressed data
|
|
/// @brief Compress a block of memory.
|
|
static uint64_t compress(char* in, unsigned size, OutputDataCallback* cb,
|
|
Algorithm hint = COMP_TYPE_BZIP2,
|
|
void* context = 0);
|
|
|
|
/// This function does the decompression work. The block of memory
|
|
/// starting at \p in and extending for \p size bytes is decompressed. The
|
|
/// decompressed output is written to memory blocks returned by the \p cb
|
|
/// callback. The caller must provide an implementation of the
|
|
/// OutputDataCallback function type and provide its address as \p cb.
|
|
/// Note that the callback function will be called as many times as
|
|
/// necessary to complete the compression of the \p in block but that the
|
|
/// total size will generally be greater than \p size. It is a good idea
|
|
/// to provide as large a value to the callback's \p size parameter as
|
|
/// possible so that fewer calls to the callback are made.
|
|
/// @throws std::string if an error occurs
|
|
/// @returns the total size of the decompressed data
|
|
/// @brief Decompress a block of memory.
|
|
static uint64_t decompress(char *in, unsigned size,
|
|
OutputDataCallback* cb, void* context = 0);
|
|
|
|
/// @}
|
|
};
|
|
}
|
|
|
|
// vim: sw=2 ai
|
|
|
|
#endif
|