diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/H5Zfletcher32.c | 69 | ||||
| -rw-r--r-- | src/H5checksum.c | 9 |
2 files changed, 9 insertions, 69 deletions
diff --git a/src/H5Zfletcher32.c b/src/H5Zfletcher32.c index 770d05a..9092452 100644 --- a/src/H5Zfletcher32.c +++ b/src/H5Zfletcher32.c @@ -48,71 +48,6 @@ const H5Z_class_t H5Z_FLETCHER32[1] = {{ /*------------------------------------------------------------------------- - * 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: Pedro Vicente, March 10, 2004 - * defined *SRC as unsigned char for all cases - * - *------------------------------------------------------------------------- - */ -static uint32_t -H5Z_filter_fletcher32_compute(void *_src, size_t len) -{ - unsigned char *src=(unsigned char *)_src; - size_t count = len; /* Number of bytes left to checksum */ - uint32_t s1 = 0, s2 = 0; /* Temporary partial checksums */ - - FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5Z_filter_fletcher32_compute) - - /* Compute checksum */ - while(count > 1) { - unsigned short tmp_src; /*To handle unusual platforms like Cray*/ - - tmp_src = (((unsigned short)src[0])<<8) | ((unsigned short)src[1]); - src +=2; - s1 += tmp_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; - } - - /* Check for single byte remaining */ - 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 @@ -167,7 +102,7 @@ H5Z_filter_fletcher32 (unsigned flags, size_t UNUSED cd_nelmts, const unsigned U UINT32DECODE(tmp_src, stored_fletcher); /* Compute checksum (can't fail) */ - fletcher = H5Z_filter_fletcher32_compute(src,src_nbytes); + fletcher = H5_fletcher32(src, src_nbytes); /* The reversed checksum. There was a bug in the calculating code of * the Fletcher32 checksum in the library before v1.6.3. The checksum @@ -201,7 +136,7 @@ H5Z_filter_fletcher32 (unsigned flags, size_t UNUSED cd_nelmts, const unsigned U unsigned char *dst; /* Temporary pointer to destination buffer */ /* Compute checksum (can't fail) */ - fletcher = H5Z_filter_fletcher32_compute(src,nbytes); + fletcher = H5_fletcher32(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") diff --git a/src/H5checksum.c b/src/H5checksum.c index 3aafd3d..9ad575d 100644 --- a/src/H5checksum.c +++ b/src/H5checksum.c @@ -80,6 +80,11 @@ * http://en.wikipedia.org/wiki/Fletcher%27s_checksum * for more details, etc. * + * Note #2: The algorithm below differs from that given in the Wikipedia + * page by copying the data into 'sum1' in a more portable way + * and also by initializing 'sum1' and 'sum2' to 0 instead of + * 0xffff (for backward compatibility reasons, mostly). + * * Return: 32-bit fletcher checksum of input buffer (can't fail) * * Programmer: Quincey Koziol @@ -92,7 +97,7 @@ H5_fletcher32(const void *_data, size_t _len) { const uint8_t *data = (const uint8_t *)_data; /* Pointer to the data to be summed */ size_t len = _len / 2; /* Length in 16-bit words */ - uint32_t sum1 = 0xffff, sum2 = 0xffff; + uint32_t sum1 = 0, sum2 = 0; FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5_fletcher32) @@ -128,6 +133,6 @@ H5_fletcher32(const void *_data, size_t _len) sum1 = (sum1 & 0xffff) + (sum1 >> 16); sum2 = (sum2 & 0xffff) + (sum2 >> 16); - FUNC_LEAVE_NOAPI(sum2 << 16 | sum1) + FUNC_LEAVE_NOAPI((sum2 << 16) | sum1) } /* end H5_fletcher32() */ |