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/***** Preamble block *********************************************************
*
* This file is part of h5py, a low-level Python interface to the HDF5 library.
*
* Copyright (C) 2008 Andrew Collette
* http://h5py.alfven.org
* License: BSD (See LICENSE.txt for full license)
*
* $Date$
*
****** End preamble block ****************************************************/
/*
Implements an LZF filter module for HDF5, using the BSD-licensed library
by Marc Alexander Lehmann (http://www.goof.com/pcg/marc/liblzf.html).
No Python-specific code is used. The filter behaves like the DEFLATE
filter, in that it is called for every type and space, and returns 0
if the data cannot be compressed.
The only public function is (int) register_lzf(void), which passes on
the result from H5Zregister.
*/
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include "hdf5.h"
#include "lzf.h"
#include "lzf_filter.h"
/* Our own versions of H5Epush_sim, as it changed in 1.8 */
#if H5_VERS_MAJOR == 1 && H5_VERS_MINOR < 7
#define PUSH_ERR(func, minor, str) H5Epush(__FILE__, func, __LINE__, H5E_PLINE, minor, str)
#define H5PY_GET_FILTER H5Pget_filter_by_id
#else
#define PUSH_ERR(func, minor, str) H5Epush1(__FILE__, func, __LINE__, H5E_PLINE, minor, str)
#define H5PY_GET_FILTER(a,b,c,d,e,f,g) H5Pget_filter_by_id2(a,b,c,d,e,f,g,NULL)
#endif
/* Deal with the mutiple definitions for H5Z_class_t.
Note: HDF5 1.6 and >= 1.8 are supported.
See https://hdfgroup.github.io/hdf5/develop/group___h5_z.html#ga93145acc38c2c60d832b7a9b0123706b
for version history.
(1) The old class should always be used for HDF5 1.6
(2) The new class should always be used for HDF5 1.8 < 1.8.3
(3) The old class should be used for HDF5 >= 1.8.3 only if the
macro H5_USE_16_API is set
*/
#if H5_VERS_MAJOR == 1 && H5_VERS_MINOR < 8
#define H5PY_H5Z_NEWCLS 0
#elif H5_VERS_MAJOR == 1 && H5_VERS_MINOR >= 8 && H5_VERS_RELEASE >= 3 && H5_USE_16_API
#define H5PY_H5Z_NEWCLS 0
#else
#define H5PY_H5Z_NEWCLS 1
#endif
size_t lzf_filter(unsigned flags, size_t cd_nelmts,
const unsigned cd_values[], size_t nbytes,
size_t *buf_size, void **buf);
herr_t lzf_set_local(hid_t dcpl, hid_t type, hid_t space);
/* Try to register the filter, passing on the HDF5 return value */
int register_lzf(void){
int retval;
#if H5PY_H5Z_NEWCLS
H5Z_class_t filter_class = {
H5Z_CLASS_T_VERS,
(H5Z_filter_t)(H5PY_FILTER_LZF),
1, 1,
"lzf",
NULL,
(H5Z_set_local_func_t)(lzf_set_local),
(H5Z_func_t)(lzf_filter)
};
#else
H5Z_class_t filter_class = {
(H5Z_filter_t)(H5PY_FILTER_LZF),
"lzf",
NULL,
(H5Z_set_local_func_t)(lzf_set_local),
(H5Z_func_t)(lzf_filter)
};
#endif
retval = H5Zregister(&filter_class);
if(retval<0){
PUSH_ERR("register_lzf", H5E_CANTREGISTER, "Can't register LZF filter");
}
return retval;
}
/* Filter setup. Records the following inside the DCPL:
1. If version information is not present, set slots 0 and 1 to the filter
revision and LZF API version, respectively.
2. Compute the chunk size in bytes and store it in slot 2.
*/
herr_t lzf_set_local(hid_t dcpl, hid_t type, hid_t space){
int ndims;
int i;
herr_t r;
unsigned int bufsize;
hsize_t chunkdims[32];
unsigned int flags;
size_t nelements = 8;
unsigned values[] = {0,0,0,0,0,0,0,0};
r = H5PY_GET_FILTER(dcpl, H5PY_FILTER_LZF, &flags, &nelements, values, 0, NULL);
if(r<0) return -1;
if(nelements < 3) nelements = 3; /* First 3 slots reserved. If any higher
slots are used, preserve the contents. */
/* It seems the H5Z_FLAG_REVERSE flag doesn't work here, so we have to be
careful not to clobber any existing version info */
if(values[0]==0) values[0] = H5PY_FILTER_LZF_VERSION;
if(values[1]==0) values[1] = LZF_VERSION;
ndims = H5Pget_chunk(dcpl, 32, chunkdims);
if(ndims<0) return -1;
if(ndims>32){
PUSH_ERR("lzf_set_local", H5E_CALLBACK, "Chunk rank exceeds limit");
return -1;
}
bufsize = H5Tget_size(type);
if(bufsize==0) return -1;
for(i=0;i<ndims;i++){
bufsize *= chunkdims[i];
}
values[2] = bufsize;
#ifdef H5PY_LZF_DEBUG
fprintf(stderr, "LZF: Computed buffer size %d\n", bufsize);
#endif
r = H5Pmodify_filter(dcpl, H5PY_FILTER_LZF, flags, nelements, values);
if(r<0) return -1;
return 1;
}
/* The filter function */
size_t lzf_filter(unsigned flags, size_t cd_nelmts,
const unsigned cd_values[], size_t nbytes,
size_t *buf_size, void **buf){
void* outbuf = NULL;
size_t outbuf_size = 0;
unsigned int status = 0; /* Return code from lzf routines */
/* We're compressing */
if(!(flags & H5Z_FLAG_REVERSE)){
/* Allocate an output buffer exactly as long as the input data; if
the result is larger, we simply return 0. The filter is flagged
as optional, so HDF5 marks the chunk as uncompressed and
proceeds.
*/
outbuf_size = (*buf_size);
outbuf = malloc(outbuf_size);
if(outbuf == NULL){
PUSH_ERR("lzf_filter", H5E_CALLBACK, "Can't allocate compression buffer");
goto failed;
}
status = lzf_compress(*buf, nbytes, outbuf, outbuf_size);
/* We're decompressing */
} else {
if((cd_nelmts>=3)&&(cd_values[2]!=0)){
outbuf_size = cd_values[2]; /* Precomputed buffer guess */
}else{
outbuf_size = (*buf_size);
}
#ifdef H5PY_LZF_DEBUG
fprintf(stderr, "Decompress %d chunk w/buffer %d\n", nbytes, outbuf_size);
#endif
while(!status){
free(outbuf);
outbuf = malloc(outbuf_size);
if(outbuf == NULL){
PUSH_ERR("lzf_filter", H5E_CALLBACK, "Can't allocate decompression buffer");
goto failed;
}
status = lzf_decompress(*buf, nbytes, outbuf, outbuf_size);
if(!status){ /* compression failed */
if(errno == E2BIG){
outbuf_size += (*buf_size);
#ifdef H5PY_LZF_DEBUG
fprintf(stderr, " Too small: %d\n", outbuf_size);
#endif
} else if(errno == EINVAL) {
PUSH_ERR("lzf_filter", H5E_CALLBACK, "Invalid data for LZF decompression");
goto failed;
} else {
PUSH_ERR("lzf_filter", H5E_CALLBACK, "Unknown LZF decompression error");
goto failed;
}
} /* if !status */
} /* while !status */
} /* compressing vs decompressing */
if(status != 0){
free(*buf);
*buf = outbuf;
*buf_size = outbuf_size;
return status; /* Size of compressed/decompressed data */
}
failed:
free(outbuf);
return 0;
} /* End filter function */
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