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/*
* Copyright © 1999-2001 NCSA
* All rights reserved.
*
* Programmer: Raymond Lu<slu@ncsa.uiuc.edu>
* Jan 3, 2003
*/
#include "H5private.h"
#include "H5Eprivate.h"
#include "H5MMprivate.h"
#include "H5Zprivate.h"
#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 unsigned int H5Z_filter_fletcher32_compute(unsigned short *buf, size_t len)
{
size_t count = len;
register unsigned int s1 = 0;
register unsigned int s2 = 0;
unsigned short *src = buf;
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 data plus the size of Fletcher32 value
*
* Failure: 0
*
* Programmer: Raymond Lu
* Jan 3, 2003
*
* Modifications:
*
*-------------------------------------------------------------------------
*/
size_t
H5Z_filter_fletcher32 (unsigned flags, size_t cd_nelmts, const unsigned cd_values[],
size_t nbytes, size_t *buf_size, void **buf)
{
size_t ret_value = 0;
void *outbuf = NULL;
unsigned char *src = (unsigned char*)(*buf);
unsigned int fletcher = 0;
FUNC_ENTER_NOAPI(H5Z_filter_fletcher32, 0);
assert(sizeof(unsigned int)==4);
if (flags & H5Z_FLAG_REVERSE) { /* Read */
size_t src_nbytes = nbytes;
unsigned int origin_fletcher;
/* Do checksum if it's enabled for read; otherwise skip it
* to save performance. */
if (!(flags & H5Z_FLAG_SKIP_EDC)) { /* Read */
unsigned char *tmp_src;
src_nbytes -= FLETCHER_LEN;
tmp_src=src+src_nbytes;
UINT32DECODE(tmp_src, origin_fletcher);
/* Compute checksum */
fletcher = H5Z_filter_fletcher32_compute((unsigned short*)src,src_nbytes);
if(origin_fletcher != fletcher)
HGOTO_ERROR(H5E_STORAGE, H5E_READERROR, 0, "data error detected by Fletcher32 checksum");
}
*buf_size = nbytes - FLETCHER_LEN;
ret_value = *buf_size;
} else { /* Write */
unsigned char *dst;
/* Compute checksum */
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 */
dst += nbytes;
UINT32ENCODE(dst, fletcher);
*buf_size = nbytes + FLETCHER_LEN;
H5MM_xfree(*buf);
*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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