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diff --git a/doc/LZOAPI.TXT b/doc/LZOAPI.TXT new file mode 100644 index 0000000..8d28584 --- /dev/null +++ b/doc/LZOAPI.TXT @@ -0,0 +1,285 @@ + +============================================================================ +LZO -- a real-time data compression library LIBRARY REFERENCE +============================================================================ + + +[ please read LZO.FAQ first ] + + +Table of Contents +================= + +1 Introduction to the LZO Library Reference +1.1 Preliminary notes +1.2 Headers +2 General +2.1 The memory model +2.2 Public integral types +2.3 Public pointer types +2.4 Public function types +3 Function reference +3.1 Initialization +3.2 Compression +3.3 Decompression +3.4 Optimization +3.5 String functions +3.6 Checksum functions +3.7 Version functions +4 Variable reference + + + +1 Introduction to the LZO Library Reference +============================================= + + +1.1 Preliminary notes +--------------------- + +- `C90' is short for ISO 9899-1990, the ANSI/ISO standard for the C + programming language + + +1.2 Headers +----------- + +This section briefly describes the headers. + +<lzo/lzoconf.h> + + Contains definitions for the basic integral and pointer types, + provides wrappers for the library calling conventions, defines + error codes and contains prototypes for the generic functions. + This file is automatically included by all LZO headers. + +<lzo/lzo1.h> +<lzo/lzo1a.h> +<lzo/lzo1b.h> +<lzo/lzo1c.h> +<lzo/lzo1f.h> +<lzo/lzo1x.h> +<lzo/lzo1y.h> +<lzo/lzo1z.h> +<lzo/lzo2a.h> + + These files provide definitions and prototypes for the + actual (de-)compression functions. + + + +2 General +========= + + +2.1 The memory model +-------------------- + +The documentation indicates that LZO requires 32-bit integers. It's +not the integer size that really matters, though, but the memory +model. If your memory model allows to access pointers at 32-bit +offsets, then there is no problem at all - LZO works fine on my +old Atari ST, which has 16 bit integers and a flat 32-bit memory model. +Using 'huge' 32-bit pointers under 16-bit DOS is a workaround for this. + +While LZO also works with a strict 16-bit memory model, I don't officially +support this because this limits the maximum block size to 64 kB - and this +makes the library incompatible with other platforms, i.e. you cannot +decompress larger blocks compressed on those platforms. + + +2.2 Public integral types +------------------------- + +lzo_uint + + used as size_t, must be 32 bits or more for compatibility reasons + +lzo_uint32 + + *must* be 32 bits or more + +lzo_bool + + can store the values 0 ("false") and 1 ("true") + +lzo_byte + + unsigned char (memory model specific) + + +2.3 Public pointer types +------------------------ + +All pointer types are memory model specific. + +lzo_voidp + + pointer to void + +lzo_bytep + + pointer to unsigned char + +lzo_bytepp + + array of pointers to unsigned char + + +2.4 Public function types +------------------------- + +lzo_compress_t + +lzo_decompress_t + +lzo_optimize_t + +lzo_callback_t + + + +3 Function reference +==================== + + +3.1 Initialization +------------------ + +int lzo_init ( void ); + + This function initializes the LZO library. It must be the first LZO + function you call, and you cannot use any of the other LZO library + functions if the call fails. + + Return value: + Returns LZO_E_OK on success, error code otherwise. + + Note: + This function is actually implemented using a macro. + + +3.2 Compression +--------------- + +All compressors compress the memory block at `src' with the uncompressed +length `src_len' to the address given by `dst'. +The length of the compressed blocked will be returned in the variable +pointed by `dst_len'. + +The two blocks may overlap under certain conditions (see examples/overlap.c), +thereby allowing "in-place" compression. + + +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +#include <lzo/lzo1x.h> + +int lzo1x_1_compress ( const lzo_bytep src, lzo_uint src_len, + lzo_bytep dst, lzo_uintp dst_len, + lzo_voidp wrkmem ); + + Algorithm: LZO1X + Compression level: LZO1X-1 + Memory requirements: LZO1X_1_MEM_COMPRESS (64 kB on 32-bit machines) + + This compressor is pretty fast. + + Return value: + Always returns LZO_E_OK (this function can never fail). + +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +#include <lzo/lzo1x.h> + +int lzo1x_999_compress ( const lzo_bytep src, lzo_uint src_len, + lzo_bytep dst, lzo_uintp dst_len, + lzo_voidp wrkmem ); + + Algorithm: LZO1X + Compression level: LZO1X-999 + Memory requirements: LZO1X_999_MEM_COMPRESS (448 kB on 32-bit machines) + + This compressor is quite slow but achieves a good compression + ratio. It is mainly intended for generating pre-compressed data. + + Return value: + Always returns LZO_E_OK (this function can never fail). + + +[ ... lots of other compressors which all follow the same principle ... ] + + + +3.3 Decompression +----------------- + +All decompressors decompress the memory block at `src' with the compressed +length `src_len' to the address given by `dst'. +The length of the decompressed block will be returned in the variable +pointed by `dst_len' - on error the number of bytes that have +been decompressed so far will be returned. + +The safe decompressors expect that the number of bytes available in +the `dst' block is passed via the variable pointed by `dst_len'. + +The two blocks may overlap under certain conditions (see examples/overlap.c), +thereby allowing "in-place" decompression. + + +Description of return values: + + LZO_E_OK + Success. + + LZO_E_INPUT_NOT_CONSUMED + The end of the compressed block has been detected before all + bytes in the compressed block have been used. + This may actually not be an error (if `src_len' is too large). + + LZO_E_INPUT_OVERRUN + The decompressor requested more bytes from the compressed + block than available. + Your data is corrupted (or `src_len' is too small). + + LZO_E_OUTPUT_OVERRUN + The decompressor requested to write more bytes to the uncompressed + block than available. + Either your data is corrupted, or you should increase the number of + available bytes passed in the variable pointed by `dst_len'. + + LZO_E_LOOKBEHIND_OVERRUN + Your data is corrupted. + + LZO_E_EOF_NOT_FOUND + No EOF code was found in the compressed block. + Your data is corrupted (or `src_len' is too small). + + LZO_E_ERROR + Any other error (data corrupted). + + +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +#include <lzo1x.h> + +int lzo1x_decompress ( const lzo_bytep src, lzo_uint src_len, + lzo_bytep dst, lzo_uintp dst_len, + lzo_voidp wrkmem ); + + Algorithm: LZO1X + Memory requirements: 0 + + +[ ... lots of other decompressors which all follow the same principle ... ] + + + +4 Variable reference +==================== + +The variables are listed alphabetically. + +[ no public variables yet ] + + + +--------------------------- END OF LZOAPI.TXT ------------------------------ + |