/*====================================================================*
- Copyright (C) 2001 Leptonica. All rights reserved.
- This software is distributed in the hope that it will be
- useful, but with NO WARRANTY OF ANY KIND.
- No author or distributor accepts responsibility to anyone for the
- consequences of using this software, or for whether it serves any
- particular purpose or works at all, unless he or she says so in
- writing. Everyone is granted permission to copy, modify and
- redistribute this source code, for commercial or non-commercial
- purposes, with the following restrictions: (1) the origin of this
- source code must not be misrepresented; (2) modified versions must
- be plainly marked as such; and (3) this notice may not be removed
- or altered from any source or modified source distribution.
*====================================================================*/
/*
* zlibmem.c
*
* 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.
*/
#include <stdio.h>
#include <stdlib.h>
#include "allheaders.h"
#ifdef HAVE_CONFIG_H
#include "config_auto.h"
#endif /* HAVE_CONFIG_H */
/* --------------------------------------------*/
#if HAVE_LIBZ /* defined in environ.h */
/* --------------------------------------------*/
#include "zlib.h"
static const l_int32 L_BUF_SIZE = 32768;
static const l_int32 ZLIB_COMPRESSION_LEVEL = 6;
/*!
* zlibCompress()
*
* Input: datain (byte buffer with input data)
* nin (number of bytes of input data)
* &nout (<return> number of bytes of output data)
* Return: 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.
*/
l_uint8 *
zlibCompress(l_uint8 *datain,
l_int32 nin,
l_int32 *pnout)
{
l_uint8 *dataout;
l_int32 status, nbytes;
l_uint8 *bufferin, *bufferout;
BBUFFER *bbin, *bbout;
z_stream z;
PROCNAME("zlibCompress");
if (!datain)
return (l_uint8 *)ERROR_PTR("datain not defined", procName, NULL);
/* Set up fixed size buffers used in z_stream */
if ((bufferin = (l_uint8 *)CALLOC(L_BUF_SIZE, sizeof(l_uint8))) == NULL)
return (l_uint8 *)ERROR_PTR("bufferin not made", procName, NULL);
if ((bufferout = (l_uint8 *)CALLOC(L_BUF_SIZE, sizeof(l_uint8))) == NULL)
return (l_uint8 *)ERROR_PTR("bufferout not made", procName, NULL);
/* Set up bbuffers and load bbin with the data */
if ((bbin = bbufferCreate(datain, nin)) == NULL)
return (l_uint8 *)ERROR_PTR("bbin not made", procName, NULL);
if ((bbout = bbufferCreate(NULL, 0)) == NULL)
return (l_uint8 *)ERROR_PTR("bbout not made", procName, NULL);
z.zalloc = (alloc_func)0;
z.zfree = (free_func)0;
z.opaque = (voidpf)0;
z.next_in = bufferin;
z.avail_in = 0;
z.next_out = bufferout;
z.avail_out = L_BUF_SIZE;
deflateInit(&z, ZLIB_COMPRESSION_LEVEL);
for ( ; ; ) {
if (z.avail_in == 0) {
z.next_in = bufferin;
bbufferWrite(bbin, bufferin, L_BUF_SIZE, &nbytes);
/* fprintf(stderr, " wrote %d bytes to bufferin\n", nbytes); */
z.avail_in = nbytes;
}
if (z.avail_in == 0)
break;
status = deflate(&z, Z_SYNC_FLUSH);
/* fprintf(stderr, " status is %d, bytesleft = %d, totalout = %d\n",
status, z.avail_out, z.total_out); */
nbytes = L_BUF_SIZE - z.avail_out;
if (nbytes) {
bbufferRead(bbout, bufferout, nbytes);
/* fprintf(stderr, " read %d bytes from bufferout\n", nbytes); */
}
z.next_out = bufferout;
z.avail_out = L_BUF_SIZE;
}
deflateEnd(&z);
bbufferDestroy(&bbin);
dataout = bbufferDestroyAndSaveData(&bbout, pnout);
FREE(bufferin);
FREE(bufferout);
return dataout;
}
/*!
* zlibUncompress()
*
* Input: datain (byte buffer with compressed input data)
* nin (number of bytes of input data)
* &nout (<return> number of bytes of output data)
* Return: dataout (uncompressed data), or null on error
*
* Notes:
* (1) See zlibCompress().
*/
l_uint8 *
zlibUncompress(l_uint8 *datain,
l_int32 nin,
l_int32 *pnout)
{
l_uint8 *dataout;
l_int32 status, nbytes;
l_uint8 *bufferin, *bufferout;
BBUFFER *bbin, *bbout;
z_stream z;
PROCNAME("zlibUncompress");
if (!datain)
return (l_uint8 *)ERROR_PTR("datain not defined", procName, NULL);
if ((bufferin = (l_uint8 *)CALLOC(L_BUF_SIZE, sizeof(l_uint8))) == NULL)
return (l_uint8 *)ERROR_PTR("bufferin not made", procName, NULL);
if ((bufferout = (l_uint8 *)CALLOC(L_BUF_SIZE, sizeof(l_uint8))) == NULL)
return (l_uint8 *)ERROR_PTR("bufferout not made", procName, NULL);
if ((bbin = bbufferCreate(datain, nin)) == NULL)
return (l_uint8 *)ERROR_PTR("bbin not made", procName, NULL);
if ((bbout = bbufferCreate(NULL, 0)) == NULL)
return (l_uint8 *)ERROR_PTR("bbout not made", procName, NULL);
z.zalloc = (alloc_func)0;
z.zfree = (free_func)0;
z.next_in = bufferin;
z.avail_in = 0;
z.next_out = bufferout;
z.avail_out = L_BUF_SIZE;
inflateInit(&z);
for ( ; ; ) {
if (z.avail_in == 0) {
z.next_in = bufferin;
bbufferWrite(bbin, bufferin, L_BUF_SIZE, &nbytes);
/* fprintf(stderr, " wrote %d bytes to bufferin\n", nbytes); */
z.avail_in = nbytes;
}
if (z.avail_in == 0)
break;
status = inflate(&z, Z_SYNC_FLUSH);
/* fprintf(stderr, " status is %d, bytesleft = %d, totalout = %d\n",
status, z.avail_out, z.total_out); */
nbytes = L_BUF_SIZE - z.avail_out;
if (nbytes) {
bbufferRead(bbout, bufferout, nbytes);
/* fprintf(stderr, " read %d bytes from bufferout\n", nbytes); */
}
z.next_out = bufferout;
z.avail_out = L_BUF_SIZE;
}
inflateEnd(&z);
bbufferDestroy(&bbin);
dataout = bbufferDestroyAndSaveData(&bbout, pnout);
FREE(bufferin);
FREE(bufferout);
return dataout;
}
/* --------------------------------------------*/
#endif /* HAVE_LIBZ */
/* --------------------------------------------*/