[GRASS-SVN] r67212 - in grass/trunk: include/defs lib/gis
svn_grass at osgeo.org
svn_grass at osgeo.org
Fri Dec 18 00:18:57 PST 2015
Author: mmetz
Date: 2015-12-18 00:18:57 -0800 (Fri, 18 Dec 2015)
New Revision: 67212
Added:
grass/trunk/lib/gis/cmprzlib.c
grass/trunk/lib/gis/compress.c
grass/trunk/lib/gis/compress.h
Removed:
grass/trunk/lib/gis/flate.c
Modified:
grass/trunk/include/defs/gis.h
Log:
libgis: generalize compression interface
Modified: grass/trunk/include/defs/gis.h
===================================================================
--- grass/trunk/include/defs/gis.h 2015-12-18 04:10:41 UTC (rev 67211)
+++ grass/trunk/include/defs/gis.h 2015-12-18 08:18:57 UTC (rev 67212)
@@ -270,12 +270,13 @@
const char *G_find_vector(char *, const char *);
const char *G_find_vector2(const char *, const char *);
-/* flate.c */
-int G_zlib_compress(const unsigned char *, int, unsigned char *, int);
-int G_zlib_expand(const unsigned char *, int, unsigned char *, int);
-int G_zlib_write(int, const unsigned char *, int);
-int G_zlib_read(int, int, unsigned char *, int);
-int G_zlib_write_noCompress(int, const unsigned char *, int);
+/* compress.c */
+int G_get_compressor(char *);
+int G_write_compressed(int, unsigned char *, int, int);
+int G_write_unompressed(int, unsigned char *, int);
+int G_read_compressed(int, int, unsigned char *, int, int);
+int G_compress(unsigned char *, int, unsigned char *, int, int);
+int G_expand(unsigned char *, int, unsigned char *, int, int);
/* geodesic.c */
int G_begin_geodesic_equation(double, double, double, double);
Copied: grass/trunk/lib/gis/cmprzlib.c (from rev 67208, grass/trunk/lib/gis/flate.c)
===================================================================
--- grass/trunk/lib/gis/cmprzlib.c (rev 0)
+++ grass/trunk/lib/gis/cmprzlib.c 2015-12-18 08:18:57 UTC (rev 67212)
@@ -0,0 +1,231 @@
+/*
+ ****************************************************************************
+ * -- GRASS Development Team --
+ *
+ * MODULE: GRASS gis library
+ * FILENAME: cmprzlib.c
+ * AUTHOR(S): Eric G. Miller <egm2 at jps.net>
+ * Markus Metz
+ * PURPOSE: To provide an interface to libz for compressing and
+ * decompressing data using DEFLATE. It's primary use is in
+ * the storage and reading of GRASS floating point rasters.
+ * It replaces the patented LZW compression interface.
+ *
+ * ALGORITHM: http://www.gzip.org/zlib/feldspar.html
+ * DATE CREATED: Dec 17 2015
+ * COPYRIGHT: (C) 2015 by the GRASS Development Team
+ *
+ * This program is free software under the GNU General Public
+ * License (version 2 or greater). Read the file COPYING that
+ * comes with GRASS for details.
+ *
+ *****************************************************************************/
+
+/********************************************************************
+ * int *
+ * G_zlib_compress (src, srz_sz, dst, dst_sz) *
+ * int src_sz, dst_sz; *
+ * unsigned char *src, *dst; *
+ * ---------------------------------------------------------------- *
+ * This function is a wrapper around the zlib deflate() function. *
+ * It uses an all or nothing call to deflate(). If you need a *
+ * continuous compression scheme, you'll have to code your own. *
+ * In order to do a single pass compression, the input src must be *
+ * copied to a buffer 1% + 12 bytes larger than the data. This may *
+ * cause performance degradation. *
+ * *
+ * The function either returns the number of bytes of compressed *
+ * data in dst, or an error code. *
+ * *
+ * Errors include: *
+ * -1 -- Compression failed. *
+ * -2 -- dst is too small. *
+ * *
+ * ================================================================ *
+ * int *
+ * G_zlib_expand (src, src_sz, dst, dst_sz) *
+ * int src_sz, dst_sz; *
+ * unsigned char *src, *dst; *
+ * ---------------------------------------------------------------- *
+ * This function is a wrapper around the zlib inflate() function. *
+ * It uses a single pass call to inflate(). If you need a contin- *
+ * uous expansion scheme, you'll have to code your own. *
+ * *
+ * The function returns the number of bytes expanded into 'dst' or *
+ * and error code. *
+ * *
+ * Errors include: *
+ * -1 -- Expansion failed. *
+ * *
+ ********************************************************************
+ */
+
+#include <grass/config.h>
+
+#ifndef HAVE_ZLIB_H
+
+#error "GRASS requires libz to compile"
+
+#else
+
+#include <zlib.h>
+#include <grass/gis.h>
+#include <grass/glocale.h>
+
+#include "G.h"
+
+static void _init_zstruct(z_stream * z)
+{
+ /* The types are defined in zlib.h, we set to NULL so zlib uses
+ * its default functions.
+ */
+ z->zalloc = (alloc_func) 0;
+ z->zfree = (free_func) 0;
+ z->opaque = (voidpf) 0;
+}
+
+
+int
+G_zlib_compress(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz)
+{
+ int err, nbytes, buf_sz;
+ unsigned char *buf;
+ z_stream c_stream;
+
+ /* Catch errors early */
+ if (src == NULL || dst == NULL)
+ return -1;
+
+ /* Don't do anything if either of these are true */
+ if (src_sz <= 0 || dst_sz <= 0)
+ return 0;
+
+ /* Output buffer has to be 1% + 12 bytes bigger for single pass deflate */
+ /* buf_sz = (int)((double)dst_sz * 1.01 + (double)12); */
+ buf_sz = compressBound(src_sz);
+ if (NULL == (buf = (unsigned char *)
+ G_calloc(buf_sz, sizeof(unsigned char))))
+ return -1;
+
+ /* Set-up for default zlib memory handling */
+ _init_zstruct(&c_stream);
+
+ /* Set-up the stream */
+ c_stream.avail_in = src_sz;
+ c_stream.next_in = (unsigned char *) src;
+ c_stream.avail_out = buf_sz;
+ c_stream.next_out = buf;
+
+ /* Initialize */
+ /* Valid zlib compression levels -1 - 9 */
+ /* zlib default: Z_DEFAULT_COMPRESSION = -1, equivalent to 6
+ * as used here, 1 gives the best compromise between speed and compression */
+ err = deflateInit(&c_stream, G__.compression_level);
+
+ /* If there was an error initializing, return -1 */
+ if (err != Z_OK) {
+ G_free(buf);
+ return -1;
+ }
+
+ /* Do single pass compression */
+ err = deflate(&c_stream, Z_FINISH);
+ if (err != Z_STREAM_END) {
+ switch (err) {
+ case Z_OK: /* Destination too small */
+ G_free(buf);
+ deflateEnd(&c_stream);
+ return -2;
+ break;
+ default: /* Give other error */
+ G_free(buf);
+ deflateEnd(&c_stream);
+ return -1;
+ break;
+ }
+ }
+
+ /* avail_out is updated to bytes remaining in buf, so bytes of compressed
+ * data is the original size minus that
+ */
+ nbytes = buf_sz - c_stream.avail_out;
+ if (nbytes >= src_sz) {
+ /* compression not possible */
+ G_free(buf);
+ deflateEnd(&c_stream);
+ return -2;
+ }
+ /* Copy the data from buf to dst */
+ for (err = 0; err < nbytes; err++)
+ dst[err] = buf[err];
+
+ G_free(buf);
+ deflateEnd(&c_stream);
+
+ return nbytes;
+} /* G_zlib_compress() */
+
+
+int
+G_zlib_expand(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz)
+{
+ int err, nbytes;
+ z_stream c_stream;
+
+ /* Catch error condition */
+ if (src == NULL || dst == NULL)
+ return -2;
+
+ /* Don't do anything if either of these are true */
+ if (src_sz <= 0 || dst_sz <= 0)
+ return 0;
+
+ /* Set-up default zlib memory handling */
+ _init_zstruct(&c_stream);
+
+ /* Set-up I/O streams */
+ c_stream.avail_in = src_sz;
+ c_stream.next_in = (unsigned char *)src;
+ c_stream.avail_out = dst_sz;
+ c_stream.next_out = dst;
+
+ /* Call zlib initilization function */
+ err = inflateInit(&c_stream);
+
+ /* If not Z_OK return error -1 */
+ if (err != Z_OK)
+ return -1;
+
+ /* Do single pass inflate */
+ err = inflate(&c_stream, Z_FINISH);
+
+ /* Number of bytes inflated to output stream is
+ * original bytes available minus what avail_out now says
+ */
+ nbytes = dst_sz - c_stream.avail_out;
+
+ /* Z_STREAM_END means all input was consumed,
+ * Z_OK means only some was processed (not enough room in dst)
+ */
+ if (!(err == Z_STREAM_END || err == Z_OK)) {
+ if (!(err == Z_BUF_ERROR && nbytes == dst_sz)) {
+ inflateEnd(&c_stream);
+ return -1;
+ }
+ /* Else, there was extra input, but requested output size was
+ * decompressed successfully.
+ */
+ }
+
+ inflateEnd(&c_stream);
+
+ return nbytes;
+} /* G_zlib_expand() */
+
+
+#endif /* HAVE_ZLIB_H */
+
+
+/* vim: set softtabstop=4 shiftwidth=4 expandtab: */
Copied: grass/trunk/lib/gis/compress.c (from rev 67208, grass/trunk/lib/gis/flate.c)
===================================================================
--- grass/trunk/lib/gis/compress.c (rev 0)
+++ grass/trunk/lib/gis/compress.c 2015-12-18 08:18:57 UTC (rev 67212)
@@ -0,0 +1,375 @@
+/*
+ ****************************************************************************
+ * -- GRASS Development Team --
+ *
+ * MODULE: GRASS gis library
+ * FILENAME: compress.c
+ * AUTHOR(S): Markus Metz
+ * PURPOSE: To provide an interface for compressing and
+ * decompressing data using various methods. Its primary
+ * use is in the storage and reading of GRASS rasters.
+ *
+ * DATE CREATED: Dec 17 2015
+ * COPYRIGHT: (C) 2015 by the GRASS Development Team
+ *
+ * This program is free software under the GNU General Public
+ * License (version 2 or greater). Read the file COPYING that
+ * comes with GRASS for details.
+ *
+ *****************************************************************************/
+
+/********************************************************************
+ * Compression methods: *
+ * 1 : RLE (generic Run-Length Encoding of single bytes) *
+ * 2 : ZLIB's DEFLATE (good speed and compression) *
+ * 3 : LZ4 (fastest, low compression) *
+ * 4 : BZIP2 (slowest, high compression) *
+ * *
+ * int *
+ * G_read_compressed (fd, rbytes, dst, nbytes, compression_type) *
+ * int fd, rbytes, nbytes; *
+ * unsigned char *dst; *
+ * ---------------------------------------------------------------- *
+ * This is the basic function for reading a compressed chunk of a *
+ * data file. The file descriptor should be in the proper location *
+ * and the 'dst' array should have enough space for the data. *
+ * 'nbytes' is the size of 'dst'. The 'rbytes' parameter is the *
+ * number of bytes to read (knowable from the offsets index). For *
+ * best results, 'nbytes' should be the exact amount of space *
+ * needed for the expansion. Too large a value of nbytes may cause *
+ * more data to be expanded than is desired. *
+ * Returns: The number of bytes decompressed into dst, or an error. *
+ * *
+ * Errors include: *
+ * -1 -- Error Reading or Decompressing data. *
+ * -2 -- Not enough space in dst. You must make dst larger *
+ * and then call the function again (remembering to *
+ * reset the file descriptor to it's proper location. *
+ * *
+ * ================================================================ *
+ * int *
+ * G_write_compressed (fd, src, nbytes, compression_type) *
+ * int fd, nbytes; *
+ * unsigned char *src; *
+ * ---------------------------------------------------------------- *
+ * This is the basic function for writing and compressing a data *
+ * chunk to a file. The file descriptor should be in the correct *
+ * location prior to this call. The function will compress 'nbytes' *
+ * of 'src' and write it to the file 'fd'. Returns the number of *
+ * bytes written or an error code: *
+ * *
+ * Errors include: *
+ * -1 -- Compression Failed. *
+ * -2 -- Unable to write to file. *
+ * *
+ * ================================================================ *
+ * int *
+ * G_write_uncompressed (fd, src, nbytes) *
+ * int fd, nbytes; *
+ * unsigned char *src; *
+ * ---------------------------------------------------------------- *
+ * Works similar to G_write_compressed() except no attempt at *
+ * compression is made. This is quicker, but may result in larger *
+ * files. *
+ * Returns the number of bytes written, or -1 for an error. It will *
+ * return an error if it fails to write nbytes. Otherwise, the *
+ * return value will always be nbytes + 1 (for compression flag). *
+ * *
+ ********************************************************************
+ */
+
+#include <grass/config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <grass/gis.h>
+#include <grass/glocale.h>
+
+#include "compress.h"
+
+#define G_COMPRESSED_NO (unsigned char)'0'
+#define G_COMPRESSED_YES (unsigned char)'1'
+
+int G_get_compressor(char *compressor)
+{
+ /* 0: NONE (no compressor)
+ * 1: RLE
+ * 2: ZLIB's DEFLATE (default)
+ * 3: LZ4
+ * 4: BZIP2
+ */
+
+ if (!compressor)
+ return 2;
+ if (G_strncasecmp(compressor, "NONE", 4) == 0)
+ return 0;
+ if (G_strncasecmp(compressor, "RLE", 3) == 0)
+ return 1;
+ if (G_strncasecmp(compressor, "ZLIB", 4) == 0)
+ return 2;
+ if (G_strncasecmp(compressor, "LZ4", 3) == 0)
+ return 3;
+ if (G_strncasecmp(compressor, "BZ", 2) == 0)
+ return 4;
+
+ G_warning(_("Unknown compressor <%s>, using default ZLIB compressor"),
+ compressor);
+ return 2;
+}
+
+int
+G_no_compress(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz)
+{
+ /* Catch errors early */
+ if (src == NULL || dst == NULL)
+ return -1;
+
+ /* Don't do anything if src is empty */
+ if (src_sz <= 0)
+ return 0;
+
+ /* dst too small */
+ if (dst_sz < src_sz)
+ return -2;
+
+ /* Copy the data from src to dst */
+ memcpy(dst, src, src_sz);
+
+ return src_sz;
+}
+
+int
+G_no_expand(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz)
+{
+ /* Catch errors early */
+ if (src == NULL || dst == NULL)
+ return -1;
+
+ /* Don't do anything if src is empty */
+ if (src_sz <= 0)
+ return 0;
+
+ /* dst too small */
+ if (dst_sz < src_sz)
+ return -2;
+
+ /* Copy the data from src to dst */
+ memcpy(dst, src, src_sz);
+
+ return src_sz;
+}
+
+/* G_*_compress() returns
+ * > 0: number of bytes in dst
+ * 0: nothing done
+ * -1: error
+ * -2: dst too small
+ */
+int
+G_compress(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz, int compressor)
+{
+ if (compressor == 0)
+ return G_no_compress(src, src_sz, dst, dst_sz);
+ if (compressor == 1)
+ return G_rle_compress(src, src_sz, dst, dst_sz);
+ if (compressor == 2)
+ return G_zlib_compress(src, src_sz, dst, dst_sz);
+ if (compressor == 3)
+ return G_lz4_compress(src, src_sz, dst, dst_sz);
+ if (compressor == 4)
+ return G_bz2_compress(src, src_sz, dst, dst_sz);
+
+ G_fatal_error(_("Request for unsupported compressor"));
+
+ return -1;
+}
+
+/* G_*_expand() returns
+ * > 0: number of bytes in dst
+ * -1: error
+ */
+int
+G_expand(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz, int compressor)
+{
+ if (compressor == 0)
+ return G_no_expand(src, src_sz, dst, dst_sz);
+ if (compressor == 1)
+ return G_rle_expand(src, src_sz, dst, dst_sz);
+ if (compressor == 2)
+ return G_zlib_expand(src, src_sz, dst, dst_sz);
+ if (compressor == 3)
+ return G_lz4_expand(src, src_sz, dst, dst_sz);
+ if (compressor == 4)
+ return G_bz2_expand(src, src_sz, dst, dst_sz);
+
+ G_fatal_error(_("Request for unsupported compressor"));
+
+ return -1;
+}
+
+int G_read_compressed(int fd, int rbytes, unsigned char *dst, int nbytes,
+ int compressor)
+{
+ int bsize, nread, err;
+ unsigned char *b;
+
+ if (dst == NULL || nbytes < 0)
+ return -2;
+
+ bsize = rbytes;
+
+ /* Our temporary input buffer for read */
+ if (NULL == (b = (unsigned char *)
+ G_calloc(bsize, sizeof(unsigned char))))
+ return -1;
+
+ /* Read from the file until we get our bsize or an error */
+ nread = 0;
+ do {
+ err = read(fd, b + nread, bsize - nread);
+ if (err >= 0)
+ nread += err;
+ } while (err > 0 && nread < bsize);
+
+ /* If the bsize if less than rbytes and we didn't get an error.. */
+ if (nread < rbytes && err > 0) {
+ G_free(b);
+ return -1;
+ }
+
+ /* Test if row is compressed */
+ if (b[0] == G_COMPRESSED_NO) {
+ /* Then just copy it to dst */
+ for (err = 0; err < nread - 1 && err < nbytes; err++)
+ dst[err] = b[err + 1];
+
+ G_free(b);
+ return (nread - 1);
+ }
+ else if (b[0] != G_COMPRESSED_YES) {
+ /* We're not at the start of a row */
+ G_free(b);
+ return -1;
+ }
+ /* Okay it's a compressed row */
+
+ /* Just call G_expand() with the buffer we read,
+ * Account for first byte being a flag
+ */
+ err = G_expand(b + 1, bsize - 1, dst, nbytes, compressor);
+
+ /* We're done with b */
+ G_free(b);
+
+ /* Return whatever G_expand() returned */
+ return err;
+
+} /* G_read_compressed() */
+
+int G_write_compressed(int fd, unsigned char *src, int nbytes,
+ int compressor)
+{
+ int dst_sz, nwritten, err;
+ unsigned char *dst, compressed;
+
+ /* Catch errors */
+ if (src == NULL || nbytes < 0)
+ return -1;
+
+ dst_sz = nbytes;
+ if (NULL == (dst = (unsigned char *)
+ G_calloc(dst_sz, sizeof(unsigned char))))
+ return -1;
+
+ /* Now just call G_compress() */
+ err = G_compress(src, nbytes, dst, dst_sz, compressor);
+
+ /* If compression succeeded write compressed row,
+ * otherwise write uncompressed row. Compression will fail
+ * if dst is too small (i.e. compressed data is larger)
+ */
+ if (err > 0 && err <= dst_sz) {
+ dst_sz = err;
+ /* Write the compression flag */
+ compressed = G_COMPRESSED_YES;
+ if (write(fd, &compressed, 1) != 1) {
+ G_free(dst);
+ return -1;
+ }
+ nwritten = 0;
+ do {
+ err = write(fd, dst + nwritten, dst_sz - nwritten);
+ if (err >= 0)
+ nwritten += err;
+ } while (err > 0 && nwritten < dst_sz);
+ /* Account for extra byte */
+ nwritten++;
+ }
+ else {
+ /* Write compression flag */
+ compressed = G_COMPRESSED_NO;
+ if (write(fd, &compressed, 1) != 1) {
+ G_free(dst);
+ return -1;
+ }
+ nwritten = 0;
+ do {
+ err = write(fd, src + nwritten, nbytes - nwritten);
+ if (err >= 0)
+ nwritten += err;
+ } while (err > 0 && nwritten < nbytes);
+ /* Account for extra byte */
+ nwritten++;
+ } /* if (err > 0) */
+
+ /* Done with the dst buffer */
+ G_free(dst);
+
+ /* If we didn't write all the data return an error */
+ if (err < 0)
+ return -2;
+
+ return nwritten;
+} /* G_write_compressed() */
+
+int G_write_uncompressed(int fd, const unsigned char *src, int nbytes)
+{
+ int err, nwritten;
+ unsigned char compressed;
+
+ /* Catch errors */
+ if (src == NULL || nbytes < 0)
+ return -1;
+
+ /* Write the compression flag */
+ compressed = G_COMPRESSED_NO;
+ if (write(fd, &compressed, 1) != 1)
+ return -1;
+
+ /* Now write the data */
+ nwritten = 0;
+ do {
+ err = write(fd, src + nwritten, nbytes - nwritten);
+ if (err > 0)
+ nwritten += err;
+ } while (err > 0 && nwritten < nbytes);
+
+ if (err < 0 || nwritten != nbytes)
+ return -1;
+
+ /* Account for extra compressed flag */
+ nwritten++;
+
+ /* That's all */
+ return nwritten;
+
+} /* G_write_uncompressed() */
+
+
+/* vim: set softtabstop=4 shiftwidth=4 expandtab: */
Added: grass/trunk/lib/gis/compress.h
===================================================================
--- grass/trunk/lib/gis/compress.h (rev 0)
+++ grass/trunk/lib/gis/compress.h 2015-12-18 08:18:57 UTC (rev 67212)
@@ -0,0 +1,50 @@
+#include <grass/config.h>
+#include <grass/gis.h>
+
+/* compressors:
+ * 0: no compression
+ * 1: RLE, unit is one byte
+ * 2: ZLIB's DEFLATE (default)
+ * 3: LZ4, fastest but lowest compression ratio
+ * 4: BZIP2: slowest but highest compression ratio
+ */
+
+/* adding a new compressor:
+ * add the corresponding functions G_*compress() and G_*_expand()
+ * if needed, add checks to configure.in and include/config.in
+ * modify G_get_compressor(), G_compress(), G_expand()
+ */
+
+/* cmprrle.c : Run Length Encoding (RLE) */
+int
+G_rle_compress(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz);
+int
+G_rle_expand(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz);
+
+/* cmprzlib.c : ZLIB's DEFLATE */
+int
+G_zlib_compress(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz);
+int
+G_zlib_expand(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz);
+
+/* cmprlz4.c : LZ4, extremely fast */
+int
+G_lz4_compress(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz);
+int
+G_lz4_expand(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz);
+
+/* cmprbzip.c : BZIP2, high compression, faster than ZLIB's DEFLATE with level 9 */
+int
+G_bz2_compress(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz);
+int
+G_bz2_expand(unsigned char *src, int src_sz, unsigned char *dst,
+ int dst_sz);
+
+/* add more here */
Deleted: grass/trunk/lib/gis/flate.c
===================================================================
--- grass/trunk/lib/gis/flate.c 2015-12-18 04:10:41 UTC (rev 67211)
+++ grass/trunk/lib/gis/flate.c 2015-12-18 08:18:57 UTC (rev 67212)
@@ -1,441 +0,0 @@
-/*
- ****************************************************************************
- * -- GRASS Development Team --
- *
- * MODULE: GRASS gis library
- * FILENAME: flate.c
- * AUTHOR(S): Eric G. Miller <egm2 at jps.net>
- * PURPOSE: To provide an interface to libz for compressing and
- * decompressing data using DEFLATE. It's primary use is in
- * the storage and reading of GRASS floating point rasters.
- * It replaces the patented LZW compression interface.
- *
- * ALGORITHM: http://www.gzip.org/zlib/feldspar.html
- * DATE CREATED: Nov 19 2000
- * COPYRIGHT: (C) 2000 by the GRASS Development Team
- *
- * This program is free software under the GNU General Public
- * License (version 2 or greater). Read the file COPYING that
- * comes with GRASS for details.
- *
- *****************************************************************************/
-
-/********************************************************************
- * int *
- * G_zlib_read (fd, rbytes, dst, nbytes) *
- * int fd, rbytes, nbytes; *
- * unsigned char *dst; *
- * ---------------------------------------------------------------- *
- * This is the basic function for reading a compressed chunk of a *
- * data file. The file descriptor should be in the proper location *
- * and the 'dst' array should have enough space for the data. *
- * 'nbytes' is the size of 'dst'. The 'rbytes' parameter is the *
- * number of bytes to read (knowable from the offsets index). For *
- * best results, 'nbytes' should be the exact amount of space *
- * needed for the expansion. Too large a value of nbytes may cause *
- * more data to be expanded than is desired. *
- * Returns: The number of bytes decompressed into dst, or an error. *
- * *
- * Errors include: *
- * -1 -- Error Reading or Decompressing data. *
- * -2 -- Not enough space in dst. You must make dst larger *
- * and then call the function again (remembering to *
- * reset the file descriptor to it's proper location. *
- * *
- * ================================================================ *
- * int *
- * G_zlib_write (fd, src, nbytes) *
- * int fd, nbytes; *
- * unsigned char *src; *
- * ---------------------------------------------------------------- *
- * This is the basic function for writing and compressing a data *
- * chunk to a file. The file descriptor should be in the correct *
- * location prior to this call. The function will compress 'nbytes' *
- * of 'src' and write it to the file 'fd'. Returns the number of *
- * bytes written or an error code: *
- * *
- * Errors include: *
- * -1 -- Compression Failed. *
- * -2 -- Unable to write to file. *
- * *
- * ================================================================ *
- * int *
- * G_zlib_write_noCompress (fd, src, nbytes) *
- * int fd, nbytes; *
- * unsigned char *src; *
- * ---------------------------------------------------------------- *
- * Works similar to G_zlib_write() except no attempt at compression *
- * is made. This is quicker, but may result in larger files. *
- * Returns the number of bytes written, or -1 for an error. It will *
- * return an error if it fails to write nbytes. Otherwise, the *
- * return value will always be nbytes + 1 (for compression flag). *
- * *
- * ================================================================ *
- * int *
- * G_zlib_compress (src, srz_sz, dst, dst_sz) *
- * int src_sz, dst_sz; *
- * unsigned char *src, *dst; *
- * ---------------------------------------------------------------- *
- * This function is a wrapper around the zlib deflate() function. *
- * It uses an all or nothing call to deflate(). If you need a *
- * continuous compression scheme, you'll have to code your own. *
- * In order to do a single pass compression, the input src must be *
- * copied to a buffer 1% + 12 bytes larger than the data. This may *
- * cause performance degradation. *
- * *
- * The function either returns the number of bytes of compressed *
- * data in dst, or an error code. *
- * *
- * Errors include: *
- * -1 -- Compression failed. *
- * -2 -- dst is too small. *
- * *
- * ================================================================ *
- * int *
- * G_zlib_expand (src, src_sz, dst, dst_sz) *
- * int src_sz, dst_sz; *
- * unsigned char *src, *dst; *
- * ---------------------------------------------------------------- *
- * This function is a wrapper around the zlib inflate() function. *
- * It uses a single pass call to inflate(). If you need a contin- *
- * uous expansion scheme, you'll have to code your own. *
- * *
- * The function returns the number of bytes expanded into 'dst' or *
- * and error code. *
- * *
- * Errors include: *
- * -1 -- Expansion failed. *
- * *
- ********************************************************************
- */
-
-#include <grass/config.h>
-
-#ifndef HAVE_ZLIB_H
-
-#error "GRASS requires libz to compile"
-
-#else
-
-#include <zlib.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <grass/gis.h>
-
-#include "G.h"
-
-#define G_ZLIB_COMPRESSED_NO (unsigned char)'0'
-#define G_ZLIB_COMPRESSED_YES (unsigned char)'1'
-
-static void _init_zstruct(z_stream * z)
-{
- /* The types are defined in zlib.h, we set to NULL so zlib uses
- * its default functions.
- */
- z->zalloc = (alloc_func) 0;
- z->zfree = (free_func) 0;
- z->opaque = (voidpf) 0;
-}
-
-int G_zlib_read(int fd, int rbytes, unsigned char *dst, int nbytes)
-{
- int bsize, nread, err;
- unsigned char *b;
-
- if (dst == NULL || nbytes < 0)
- return -2;
-
- bsize = rbytes;
-
- /* Our temporary input buffer for read */
- if (NULL == (b = (unsigned char *)
- G_calloc(bsize, sizeof(unsigned char))))
- return -1;
-
- /* Read from the file until we get our bsize or an error */
- nread = 0;
- do {
- err = read(fd, b + nread, bsize - nread);
- if (err >= 0)
- nread += err;
- } while (err > 0 && nread < bsize);
-
- /* If the bsize if less than rbytes and we didn't get an error.. */
- if (nread < rbytes && err > 0) {
- G_free(b);
- return -1;
- }
-
- /* Test if row is compressed */
- if (b[0] == G_ZLIB_COMPRESSED_NO) {
- /* Then just copy it to dst */
- for (err = 0; err < nread - 1 && err < nbytes; err++)
- dst[err] = b[err + 1];
-
- G_free(b);
- return (nread - 1);
- }
- else if (b[0] != G_ZLIB_COMPRESSED_YES) {
- /* We're not at the start of a row */
- G_free(b);
- return -1;
- }
- /* Okay it's a compressed row */
-
- /* Just call G_zlib_expand() with the buffer we read,
- * Account for first byte being a flag
- */
- err = G_zlib_expand(b + 1, bsize - 1, dst, nbytes);
-
- /* We're done with b */
- G_free(b);
-
- /* Return whatever G_zlib_expand() returned */
- return err;
-
-} /* G_zlib_read() */
-
-
-int G_zlib_write(int fd, const unsigned char *src, int nbytes)
-{
- int dst_sz, nwritten, err;
- unsigned char *dst, compressed;
-
- /* Catch errors */
- if (src == NULL || nbytes < 0)
- return -1;
-
- dst_sz = nbytes;
- if (NULL == (dst = (unsigned char *)
- G_calloc(dst_sz, sizeof(unsigned char))))
- return -1;
-
- /* Now just call G_zlib_compress() */
- err = G_zlib_compress(src, nbytes, dst, dst_sz);
-
- /* If compression succeeded write compressed row,
- * otherwise write uncompressed row. Compression will fail
- * if dst is too small (i.e. compressed data is larger)
- */
- if (err > 0 && err <= dst_sz) {
- dst_sz = err;
- /* Write the compression flag */
- compressed = G_ZLIB_COMPRESSED_YES;
- if (write(fd, &compressed, 1) != 1) {
- G_free(dst);
- return -1;
- }
- nwritten = 0;
- do {
- err = write(fd, dst + nwritten, dst_sz - nwritten);
- if (err >= 0)
- nwritten += err;
- } while (err > 0 && nwritten < dst_sz);
- /* Account for extra byte */
- nwritten++;
- }
- else {
- /* Write compression flag */
- compressed = G_ZLIB_COMPRESSED_NO;
- if (write(fd, &compressed, 1) != 1) {
- G_free(dst);
- return -1;
- }
- nwritten = 0;
- do {
- err = write(fd, src + nwritten, nbytes - nwritten);
- if (err >= 0)
- nwritten += err;
- } while (err > 0 && nwritten < nbytes);
- /* Account for extra byte */
- nwritten++;
- } /* if (err > 0) */
-
- /* Done with the dst buffer */
- G_free(dst);
-
- /* If we didn't write all the data return an error */
- if (err < 0)
- return -2;
-
- return nwritten;
-} /* G_zlib_write() */
-
-
-int G_zlib_write_noCompress(int fd, const unsigned char *src, int nbytes)
-{
- int err, nwritten;
- unsigned char compressed;
-
- /* Catch errors */
- if (src == NULL || nbytes < 0)
- return -1;
-
- /* Write the compression flag */
- compressed = G_ZLIB_COMPRESSED_NO;
- if (write(fd, &compressed, 1) != 1)
- return -1;
-
- /* Now write the data */
- nwritten = 0;
- do {
- err = write(fd, src + nwritten, nbytes - nwritten);
- if (err > 0)
- nwritten += err;
- } while (err > 0 && nwritten < nbytes);
-
- if (err < 0 || nwritten != nbytes)
- return -1;
-
- /* Account for extra compressed flag */
- nwritten++;
-
- /* That's all */
- return nwritten;
-
-} /* G_zlib_write_noCompress() */
-
-
-int
-G_zlib_compress(const unsigned char *src, int src_sz, unsigned char *dst,
- int dst_sz)
-{
- int err, nbytes, buf_sz;
- unsigned char *buf;
- z_stream c_stream;
-
- /* Catch errors early */
- if (src == NULL || dst == NULL)
- return -1;
-
- /* Don't do anything if either of these are true */
- if (src_sz <= 0 || dst_sz <= 0)
- return 0;
-
- /* Output buffer has to be 1% + 12 bytes bigger for single pass deflate */
- buf_sz = (int)((double)dst_sz * 1.01 + (double)12);
- if (NULL == (buf = (unsigned char *)
- G_calloc(buf_sz, sizeof(unsigned char))))
- return -1;
-
- /* Set-up for default zlib memory handling */
- _init_zstruct(&c_stream);
-
- /* Set-up the stream */
- c_stream.avail_in = src_sz;
- c_stream.next_in = (unsigned char *) src;
- c_stream.avail_out = buf_sz;
- c_stream.next_out = buf;
-
- /* Initialize */
- /* Valid zlib compression levels -1 - 9 */
- /* zlib default: Z_DEFAULT_COMPRESSION = -1, equivalent to 6
- * as used here, 1 gives the best compromise between speed and compression */
- err = deflateInit(&c_stream,
- (G__.compression_level < -1 || G__.compression_level > 9)
- ? 1 : G__.compression_level);
-
- /* If there was an error initializing, return -1 */
- if (err != Z_OK) {
- G_free(buf);
- return -1;
- }
-
- /* Do single pass compression */
- err = deflate(&c_stream, Z_FINISH);
- if (err != Z_STREAM_END) {
- switch (err) {
- case Z_OK: /* Destination too small */
- G_free(buf);
- deflateEnd(&c_stream);
- return -2;
- break;
- default: /* Give other error */
- G_free(buf);
- deflateEnd(&c_stream);
- return -1;
- break;
- }
- }
-
- /* avail_out is updated to bytes remaining in buf, so bytes of compressed
- * data is the original size minus that
- */
- nbytes = buf_sz - c_stream.avail_out;
- if (nbytes > dst_sz) { /* Not enough room to copy output */
- G_free(buf);
- deflateEnd(&c_stream);
- return -2;
- }
- /* Copy the data from buf to dst */
- for (err = 0; err < nbytes; err++)
- dst[err] = buf[err];
-
- G_free(buf);
- deflateEnd(&c_stream);
-
- return nbytes;
-} /* G_zlib_compress() */
-
-int
-G_zlib_expand(const unsigned char *src, int src_sz, unsigned char *dst,
- int dst_sz)
-{
- int err, nbytes;
- z_stream c_stream;
-
- /* Catch error condition */
- if (src == NULL || dst == NULL)
- return -2;
-
- /* Don't do anything if either of these are true */
- if (src_sz <= 0 || dst_sz <= 0)
- return 0;
-
- /* Set-up default zlib memory handling */
- _init_zstruct(&c_stream);
-
- /* Set-up I/O streams */
- c_stream.avail_in = src_sz;
- c_stream.next_in = (unsigned char *)src;
- c_stream.avail_out = dst_sz;
- c_stream.next_out = dst;
-
- /* Call zlib initilization function */
- err = inflateInit(&c_stream);
-
- /* If not Z_OK return error -1 */
- if (err != Z_OK)
- return -1;
-
- /* Do single pass inflate */
- err = inflate(&c_stream, Z_FINISH);
-
- /* Number of bytes inflated to output stream is
- * original bytes available minus what avail_out now says
- */
- nbytes = dst_sz - c_stream.avail_out;
-
- /* Z_STREAM_END means all input was consumed,
- * Z_OK means only some was processed (not enough room in dst)
- */
- if (!(err == Z_STREAM_END || err == Z_OK)) {
- if (!(err == Z_BUF_ERROR && nbytes == dst_sz)) {
- inflateEnd(&c_stream);
- return -1;
- }
- /* Else, there was extra input, but requested output size was
- * decompressed successfully.
- */
- }
-
- inflateEnd(&c_stream);
-
- return nbytes;
-} /* G_zlib_expand() */
-
-#endif /* HAVE_ZLIB_H */
-
-
-/* vim: set softtabstop=4 shiftwidth=4 expandtab: */
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