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Compression

Functions

Name
int wc_Compress(byte * out, word32 outSz, const byte * in, word32 inSz, word32 flags)
This function compresses the given input data using Huffman coding and stores the output in out. Note that the output buffer should still be larger than the input buffer because there exists a certain input for which there will be no compression possible, which will still require a lookup table. It is recommended that one allocate srcSz + 0.1% + 12 for the output buffer.
int wc_DeCompress(byte * out, word32 outSz, const byte * in, word32 inSz)
This function decompresses the given compressed data using Huffman coding and stores the output in out.

Functions Documentation

function wc_Compress

int wc_Compress(
    byte * out,
    word32 outSz,
    const byte * in,
    word32 inSz,
    word32 flags
)

This function compresses the given input data using Huffman coding and stores the output in out. Note that the output buffer should still be larger than the input buffer because there exists a certain input for which there will be no compression possible, which will still require a lookup table. It is recommended that one allocate srcSz + 0.1% + 12 for the output buffer.

Parameters:

  • out pointer to the output buffer in which to store the compressed data
  • outSz size available in the output buffer for storage
  • in pointer to the buffer containing the message to compress
  • inSz size of the input message to compress
  • flags flags to control how compression operates. Use 0 for normal decompression

See: wc_DeCompress

Return:

  • On successfully compressing the input data, returns the number of bytes stored in the output buffer
  • COMPRESS_INIT_E Returned if there is an error initializing the stream for compression
  • COMPRESS_E Returned if an error occurs during compression

Example

byte message[] = { // initialize text to compress };
byte compressed[(sizeof(message) + sizeof(message) * .001 + 12 )];
// Recommends at least srcSz + .1% + 12

if( wc_Compress(compressed, sizeof(compressed), message, sizeof(message),
0) != 0){
    // error compressing data
}

function wc_DeCompress

int wc_DeCompress(
    byte * out,
    word32 outSz,
    const byte * in,
    word32 inSz
)

This function decompresses the given compressed data using Huffman coding and stores the output in out.

Parameters:

  • out pointer to the output buffer in which to store the decompressed data
  • outSz size available in the output buffer for storage
  • in pointer to the buffer containing the message to decompress
  • inSz size of the input message to decompress

See: wc_Compress

Return:

  • Success On successfully decompressing the input data, returns the number of bytes stored in the output buffer
  • COMPRESS_INIT_E: Returned if there is an error initializing the stream for compression
  • COMPRESS_E: Returned if an error occurs during compression

Example

byte compressed[] = { // initialize compressed message };
byte decompressed[MAX_MESSAGE_SIZE];

if( wc_DeCompress(decompressed, sizeof(decompressed),
compressed, sizeof(compressed)) != 0 ) {
    // error decompressing data
}

Updated on 2024-12-20 at 01:22:24 +0000