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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the files COPYING and Copyright.html. COPYING can be found at the root *
* of the source code distribution tree; Copyright.html can be found at the *
* root level of an installed copy of the electronic HDF5 document set and *
* is linked from the top-level documents page. It can also be found at *
* http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html. If you do not have *
* access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* Programmer: Raymond Lu<slu@ncsa.uiuc.edu>
* Jan 3, 2003
*/
#include "H5private.h" /* Generic Functions */
#include "H5Eprivate.h" /* Error handling */
#include "H5MMprivate.h" /* Memory management */
#include "H5Zprivate.h" /* Data filters */
#ifdef H5_HAVE_FILTER_FLETCHER32
#define FLETCHER_LEN 4
/* Interface initialization */
#define PABLO_MASK H5Z_fletcher32_mask
#define INTERFACE_INIT NULL
static int interface_initialize_g = 0;
/*-------------------------------------------------------------------------
* Function: H5Z_filter_fletcher32_compute
*
* Purpose: Implement an Fletcher32 Checksum using 1's complement.
*
* Return: Success: Fletcher32 value
*
* Failure: Can't fail
*
* Programmer: Raymond Lu
* Jan 3, 2003
*
* Modifications:
*
*-------------------------------------------------------------------------
*/
static uint32_t H5Z_filter_fletcher32_compute(unsigned short *src, size_t len)
{
size_t count = len; /* Number of bytes left to checksum */
uint32_t s1 = 0, s2 = 0; /* Temporary partial checksums */
FUNC_ENTER_NOINIT(H5Z_filter_fletcher32_compute);
/* Compute checksum */
while(count > 1) {
s1 += *src++;
if(s1 & 0xFFFF0000) { /*Wrap around carry if occurred*/
s1 &= 0xFFFF;
s1++;
}
s2 += s1;
if(s2 & 0xFFFF0000) { /*Wrap around carry if occurred*/
s2 &= 0xFFFF;
s2++;
}
count -= 2;
}
if(count==1) {
s1 += *(unsigned char*)src;
if(s1 & 0xFFFF0000) { /*Wrap around carry if occurred*/
s1 &= 0xFFFF;
s1++;
}
s2 += s1;
if(s2 & 0xFFFF0000) { /*Wrap around carry if occurred*/
s2 &= 0xFFFF;
s2++;
}
}
FUNC_LEAVE_NOAPI((s2 << 16) + s1);
}
/*-------------------------------------------------------------------------
* Function: H5Z_filter_fletcher32
*
* Purpose: Implement an I/O filter of Fletcher32 Checksum
*
* Return: Success: Size of buffer filtered
* Failure: 0
*
* Programmer: Raymond Lu
* Jan 3, 2003
*
* Modifications:
*
*-------------------------------------------------------------------------
*/
size_t
H5Z_filter_fletcher32 (unsigned flags, size_t UNUSED cd_nelmts, const unsigned UNUSED cd_values[],
size_t nbytes, size_t *buf_size, void **buf)
{
void *outbuf = NULL; /* Pointer to new buffer */
unsigned char *src = (unsigned char*)(*buf);
uint32_t fletcher; /* Checksum value */
size_t ret_value; /* Return value */
FUNC_ENTER_NOAPI(H5Z_filter_fletcher32, 0);
assert(sizeof(uint32_t)==4);
if (flags & H5Z_FLAG_REVERSE) { /* Read */
/* Do checksum if it's enabled for read; otherwise skip it
* to save performance. */
if (!(flags & H5Z_FLAG_SKIP_EDC)) {
unsigned char *tmp_src; /* Pointer to checksum in buffer */
size_t src_nbytes = nbytes; /* Original number of bytes */
uint32_t stored_fletcher; /* Stored checksum value */
/* Get the stored checksum */
src_nbytes -= FLETCHER_LEN;
tmp_src=src+src_nbytes;
UINT32DECODE(tmp_src, stored_fletcher);
/* Compute checksum (can't fail) */
fletcher = H5Z_filter_fletcher32_compute((unsigned short*)src,src_nbytes);
/* Verify computed checksum matches stored checksum */
if(stored_fletcher != fletcher)
HGOTO_ERROR(H5E_STORAGE, H5E_READERROR, 0, "data error detected by Fletcher32 checksum");
}
/* Set return values */
/* (Re-use the input buffer, just note that the size is smaller by the size of the checksum) */
ret_value = nbytes-FLETCHER_LEN;
} else { /* Write */
unsigned char *dst; /* Temporary pointer to destination buffer */
/* Compute checksum (can't fail) */
fletcher = H5Z_filter_fletcher32_compute((unsigned short*)src,nbytes);
if (NULL==(dst=outbuf=H5MM_malloc(nbytes+FLETCHER_LEN)))
HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "unable to allocate Fletcher32 checksum destination buffer");
/* Copy raw data */
HDmemcpy((void*)dst, (void*)(*buf), nbytes);
/* Append checksum to raw data for storage */
dst += nbytes;
UINT32ENCODE(dst, fletcher);
/* Free input buffer */
H5MM_xfree(*buf);
/* Set return values */
*buf_size = nbytes + FLETCHER_LEN;
*buf = outbuf;
outbuf = NULL;
ret_value = *buf_size;
}
done:
if(outbuf)
H5MM_xfree(outbuf);
FUNC_LEAVE_NOAPI(ret_value);
}
#endif /* H5_HAVE_FILTER_FLETCHER32 */
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