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Restrict the interface to not allow algorithm selection

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llvm-svn: 18248
This commit is contained in:
Reid Spencer 2004-11-25 19:37:42 +00:00
parent 1e5db2e2da
commit 0fd67aa7c9
1 changed files with 18 additions and 35 deletions
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53
include/llvm/Support/Compressor.h
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@ -19,32 +19,23 @@
namespace llvm { namespace llvm {
/// This class provides an abstraction for compressing a block of memory using /// This class provides an abstraction for compression and decompression of
/// a standard compression utility such as bzip2 or libz. This interface /// a block of memory. The algorithm used here is currently bzip2 but that
/// allows us to abstract the notion of compression and deal with alternate /// may change without notice. Should newer algorithms prove to compress
/// compression scheme availability depending on the configured platform. This /// bytecode better than bzip2, that newer algorithm will be added, but won't
/// facility will always favor a bzip2 implementation if its available. /// replace bzip2. This interface allows us to abstract the notion of
/// Otherwise, libz will be used if it is available. If neither zlib nor bzip2 /// compression and deal with alternate compression schemes over time.
/// are available, a very simple algorithm provided by the Compressor class /// The type of compression used can be determined by inspecting the
/// will be used. The type of compression used can be determined by inspecting /// first byte of the compressed output. Currently value '0' means no
/// the first byte of the compressed output. ASCII values '0', '1', and '2', /// compression was used (for very small files) and value '2' means bzip2
/// denote the compression type as given in the Algorithm enumeration below. /// compression was used. The Compressor is intended for use with memory
/// The Compressor is intended for use with memory mapped files where the /// mapped files where the entire data block to be compressed or decompressed
/// entire data block to be compressed or decompressed is available in /// is available in memory. However, output can be gathered in repeated calls
/// memory. However, output can be gathered in repeated calls to a callback. /// to a callback. Utilities for sending compressed or decompressed output
/// to a stream or directly to a memory block are also provided.
/// @since 1.4 /// @since 1.4
/// @brief An abstraction for memory to memory data (de)compression /// @brief An abstraction for memory to memory data (de)compression
class Compressor { 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)
};
/// @}
/// @name High Level Interface /// @name High Level Interface
/// @{ /// @{
public: public:
@ -58,9 +49,7 @@ namespace llvm {
static uint64_t compressToNewBuffer( static uint64_t compressToNewBuffer(
const char* in, ///< The buffer to be compressed const char* in, ///< The buffer to be compressed
unsigned size, ///< The size of the buffer to be compressed unsigned size, ///< The size of the buffer to be compressed
char*&out, ///< The returned output buffer char*&out ///< The returned output buffer
Algorithm hint ///< Hint for type of compression to perform
= COMP_TYPE_BZIP2
); );
/// This method compresses a block of memory pointed to by \p in with /// This method compresses a block of memory pointed to by \p in with
@ -73,9 +62,7 @@ namespace llvm {
static uint64_t compressToStream( static uint64_t compressToStream(
const char*in, ///< The buffer to be compressed const char*in, ///< The buffer to be compressed
unsigned size, ///< The size of the buffer to be compressed unsigned size, ///< The size of the buffer to be compressed
std::ostream& out, ///< The output stream to write data on std::ostream& out ///< The output stream to write data on
Algorithm hint ///< Hint for type of compression to perform
= COMP_TYPE_BZIP2
); );
/// This method decompresses a block of memory pointed to by \p in with /// This method decompresses a block of memory pointed to by \p in with
@ -140,10 +127,7 @@ namespace llvm {
const char* in, ///< The buffer to be compressed const char* in, ///< The buffer to be compressed
unsigned size, ///< The size of the buffer to be compressed unsigned size, ///< The size of the buffer to be compressed
OutputDataCallback* cb, ///< Call back for memory allocation OutputDataCallback* cb, ///< Call back for memory allocation
Algorithm hint ///< Hint for type of compression to perform void* context = 0 ///< Context for callback
= COMP_TYPE_BZIP2,
void* context ///< Context for callback
= 0
); );
/// This function does the decompression work. The block of memory /// This function does the decompression work. The block of memory
@ -163,8 +147,7 @@ namespace llvm {
const char *in, ///< The buffer to be decompressed const char *in, ///< The buffer to be decompressed
unsigned size, ///< Size of the buffer to be decompressed unsigned size, ///< Size of the buffer to be decompressed
OutputDataCallback* cb, ///< Call back for memory allocation OutputDataCallback* cb, ///< Call back for memory allocation
void* context ///< Context for callback void* context = 0 ///< Context for callback
= 0
); );
/// @} /// @}