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Diffstat (limited to 'src/zlibmem.c')
-rw-r--r-- | src/zlibmem.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/src/zlibmem.c b/src/zlibmem.c new file mode 100644 index 0000000..a2b5c0d --- /dev/null +++ b/src/zlibmem.c @@ -0,0 +1,254 @@ +/*====================================================================* + - Copyright (C) 2001 Leptonica. All rights reserved. + - + - Redistribution and use in source and binary forms, with or without + - modification, are permitted provided that the following conditions + - are met: + - 1. Redistributions of source code must retain the above copyright + - notice, this list of conditions and the following disclaimer. + - 2. Redistributions in binary form must reproduce the above + - copyright notice, this list of conditions and the following + - disclaimer in the documentation and/or other materials + - provided with the distribution. + - + - THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + - ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + - LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + - A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ANY + - CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + - EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + - PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + - PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY + - OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + - NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + - SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + *====================================================================*/ + + +/* + * 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. + */ + +#ifdef HAVE_CONFIG_H +#include "config_auto.h" +#endif /* HAVE_CONFIG_H */ + +#include "allheaders.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; + +#ifndef NO_CONSOLE_IO +#define DEBUG 0 +#endif /* ~NO_CONSOLE_IO */ + + +/*! + * 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, + size_t nin, + size_t *pnout) +{ +l_uint8 *dataout; +l_int32 status; +l_int32 flush; +size_t nbytes; +l_uint8 *bufferin, *bufferout; +L_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 *)LEPT_CALLOC(L_BUF_SIZE, sizeof(l_uint8))) + == NULL) + return (l_uint8 *)ERROR_PTR("bufferin not made", procName, NULL); + if ((bufferout = (l_uint8 *)LEPT_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; + + status = deflateInit(&z, ZLIB_COMPRESSION_LEVEL); + if (status != Z_OK) + return (l_uint8 *)ERROR_PTR("deflateInit failed", procName, NULL); + + do { + if (z.avail_in == 0) { + z.next_in = bufferin; + bbufferWrite(bbin, bufferin, L_BUF_SIZE, &nbytes); +#if DEBUG + fprintf(stderr, " wrote %lu bytes to bufferin\n", + (unsigned long)nbytes); +#endif /* DEBUG */ + z.avail_in = nbytes; + } + flush = (bbin->n) ? Z_SYNC_FLUSH : Z_FINISH; + status = deflate(&z, flush); +#if DEBUG + fprintf(stderr, " status is %d, bytesleft = %u, totalout = %lu\n", + status, z.avail_out, z.total_out); +#endif /* DEBUG */ + nbytes = L_BUF_SIZE - z.avail_out; + if (nbytes) { + bbufferRead(bbout, bufferout, nbytes); +#if DEBUG + fprintf(stderr, " read %lu bytes from bufferout\n", + (unsigned long)nbytes); +#endif /* DEBUG */ + } + z.next_out = bufferout; + z.avail_out = L_BUF_SIZE; + } while (flush != Z_FINISH); + + deflateEnd(&z); + + bbufferDestroy(&bbin); + dataout = bbufferDestroyAndSaveData(&bbout, pnout); + + LEPT_FREE(bufferin); + LEPT_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, + size_t nin, + size_t *pnout) +{ +l_uint8 *dataout; +l_uint8 *bufferin, *bufferout; +l_int32 status; +size_t nbytes; +L_BBUFFER *bbin, *bbout; +z_stream z; + + PROCNAME("zlibUncompress"); + + if (!datain) + return (l_uint8 *)ERROR_PTR("datain not defined", procName, NULL); + + if ((bufferin = (l_uint8 *)LEPT_CALLOC(L_BUF_SIZE, sizeof(l_uint8))) + == NULL) + return (l_uint8 *)ERROR_PTR("bufferin not made", procName, NULL); + if ((bufferout = (l_uint8 *)LEPT_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); + + LEPT_FREE(bufferin); + LEPT_FREE(bufferout); + return dataout; +} + +/* --------------------------------------------*/ +#endif /* HAVE_LIBZ */ +/* --------------------------------------------*/ |