COMPRESS Function

COMPRESS(input, input_len, output, output_max_len, level)

Compresses a memory buffer using gzip compression.

Compressed data is written to the output buffer and the function returns the compressed size in bytes.

Returns zero on error.

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Examples

REM Compress a memory buffer
 
INPUT_BUFFER = MEMALLOC(1024)
OUTPUT_BUFFER = MEMALLOC(2048)
 
REM Fill input buffer here
 
SIZE = COMPRESS(INPUT_BUFFER, 1024, OUTPUT_BUFFER, 2048, 6)
 
PRINT "Compressed size: "; SIZE

REM Compress a file loaded into memory
 
F = OPENIN("data.bin")
 
SIZE = FILESIZE("data.bin")
 
INPUT = MEMALLOC(SIZE)
OUTPUT = MEMALLOC(SIZE * 2)
 
BINREAD F, INPUT, SIZE
CLOSE F
 
COMPRESSED = COMPRESS(INPUT, SIZE, OUTPUT, SIZE * 2, 9)
 
PRINT "Compressed "; SIZE; " bytes into "; COMPRESSED

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Notes

• input is the source memory buffer.
• input_len is the size of the source data in bytes.
• output is the destination memory buffer.
• output_max_len is the maximum writable size of the output buffer.
• level is the gzip compression level from 0 to 9.
• Higher compression levels are slower but may produce smaller output.
• The output buffer must be large enough to hold the compressed data.
• Returns the compressed size in bytes.
• Returns zero if compression fails.

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Errors

• Compression failed
• Output buffer too small

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See also: DECOMPRESS · MEMALLOC · MEMRELEASE · BINREAD · BINWRITE