ncompress42 source code

1 module ncompress42;
2 
3 /**
4  * Used for emulating file reads, as the library is a port of ncompress.
5  * The function must return the number of bytes read, 0 if EoF (or end of datasteam) has reached,
6  * or -1 on errors.
7  * rwCtxt can contain filenames if they're applicable.
8  */
9 alias NCmpStreamReader = extern (C) int function(ubyte* bytes, size_t numBytes, void* rwCtxt);
10 /**
11  * Used for emulating file writes.
12  * It must return the number of files pushed, or -1 on error
13  */
14 alias NCmpStreamWriter = extern (C) int function(const(ubyte)* bytes, size_t numBytes, void* rwCtxt);
15 
16 /**
17  * Used for storing function pointers and other contextual stuff.
18  */
19 struct NCompressCtxt
20 {
21     NCmpStreamReader reader;
22     NCmpStreamWriter writer;
23     void* rwCtxt; // context for the reader and writer
24 
25     void* priv;
26 }
27 
28 /** 
29  * Error codes, mainly from decompression.
30  */
31 enum NCompressError
32 {
33     NCMP_OK = 0,
34 
35     NCMP_READ_ERROR, // an error from the reader
36     NCMP_WRITE_ERROR, // an error from the writer
37 
38     NCMP_DATA_ERROR, // invalid compressed data format
39     NCMP_BITS_ERROR, // compressed with too large a bits parameter
40     NCMP_OTHER_ERROR, // some other internal error
41 }
42 
43 extern (C):
44 /** 
45  * Initialise for compression.
46  * Set the reader, writer and read-write context in
47  * the CompressCtxt struct. Then call initCompress()
48  * The bits parameter is only used when compressing. It sets the maximum
49  * size of a code word. The value must be in the range 9 to 16 or else
50  * zero to select the default of 16.
51  */
52 void nInitCompress(NCompressCtxt* ctxt, int bits);
53 /**
54  * Initialise for decompression.
55  * Set the reader, writer and read-write context in
56  * the CompressCtxt struct. Then call initDecompress()
57  */
58 void nInitDecompress(NCompressCtxt* ctxt);
59 ///Frees all buffers up.
60 void nFreeCompress(NCompressCtxt* ctxt);
61 ///Compresses the datasteam
62 NCompressError nCompress(NCompressCtxt* ctxt);
63 ///Decompresses the datastream
64 NCompressError nDecompress(NCompressCtxt* ctxt);