#include "allheaders.h"
#include "zlib.h"

Macros
#define	DEBUG 0

Functions
l_uint8 *	zlibCompress (l_uint8 datain, size_t nin, size_t pnout)

l_uint8 *	zlibUncompress (l_uint8 datain, size_t nin, size_t pnout)

Variables
static const l_int32	L_BUF_SIZE = 32768

static const l_int32	ZLIB_COMPRESSION_LEVEL = 6

Detailed Description

 zlib operations in memory, using bbuffer
     l_uint8   *zlibCompress()
     l_uint8   *zlibUncompress()

   This provides an example use of the byte buffer utility
   (see bbuffer.c for details of how the bbuffer works internally).
   We use zlib to compress and decompress a byte array from
   one memory buffer to another.  The standard method uses streams,
   but here we use the bbuffer as an expandable queue of pixels
   for both the reading and writing sides of each operation.

   With memory mapping, one should be able to compress between
   memory buffers by using the file system to buffer everything in
   the background, but the bbuffer implementation is more portable.

Definition in file zlibmem.c.

Function Documentation

◆ zlibCompress()

l_uint8* zlibCompress	(	l_uint8 *	datain,
		size_t	nin,
		size_t *	pnout
	)

zlibCompress()

Parameters

[in]	datain	byte buffer with input data
[in]	nin	number of bytes of input data
[out]	pnout	number of bytes of output data

Returns: dataout compressed data, or NULL on error

Notes:
     (1) We repeatedly read in and fill up an input buffer,
         compress the data, and read it back out.  zlib
         uses two byte buffers internally in the z_stream
         data structure.  We use the bbuffers to feed data
         into the fixed bufferin, and feed it out of bufferout,
         in the same way that a pair of streams would normally
         be used if the data were being read from one file
         and written to another.  This is done iteratively,
         compressing L_BUF_SIZE bytes of input data at a time.

Definition at line 92 of file zlibmem.c.

References bbufferCreate(), and L_BUF_SIZE.

Referenced by l_genDataString().