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author | 2012-07-09 17:40:48 +0000 | |
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committer | 2012-07-09 17:40:48 +0000 | |
commit | fc8581b2d8c63439162c701623bce096088ce6e6 (patch) | |
tree | cf63f8899846e2c94c71af0df46f2b01dc6ab316 /include/core/SkChecksum.h | |
parent | f8affe5adff8e82ca6a3e5b98b0d772e204edc51 (diff) |
revert 4478
git-svn-id: http://skia.googlecode.com/svn/trunk@4479 2bbb7eff-a529-9590-31e7-b0007b416f81
Diffstat (limited to 'include/core/SkChecksum.h')
-rw-r--r-- | include/core/SkChecksum.h | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/include/core/SkChecksum.h b/include/core/SkChecksum.h index e66df54aaf..e767670191 100644 --- a/include/core/SkChecksum.h +++ b/include/core/SkChecksum.h @@ -10,6 +10,64 @@ #include "SkTypes.h" +#if !defined(SK_PREFER_32BIT_CHECKSUM) +#define SK_PREFER_32BIT_CHECKSUM 0 +#endif + +enum { + ChecksumRotateBits = 17 +}; + +#define SkCHECKSUM_MASH(CHECKSUM, NEW_CHUNK) \ + CHECKSUM = (((CHECKSUM) >> (sizeof(CHECKSUM)*8 - ChecksumRotateBits)) + \ + ((CHECKSUM) << ChecksumRotateBits)) ^ (NEW_CHUNK); + + +/** + * Compute a 64-bit checksum for a given data block + * + * @param data Memory address of the data block to be processed. Must be + * 32-bit aligned + * @param size Size of the data block in bytes. Must be a multiple of 8. + * @return checksum result + */ +inline uint64_t SkComputeChecksum64(const uint64_t* ptr, size_t size) { + SkASSERT(SkIsAlign8(size)); + // Strict 8-byte alignment is not required on ptr. On current + // CPUs there is no measurable performance difference between 32-bit + // and 64-bit aligned access to uint64_t data + SkASSERT(SkIsAlign4((intptr_t)ptr)); + + const uint64_t* stop = ptr + (size >> 3); + uint64_t result = 0; + while (ptr < stop) { + SkCHECKSUM_MASH(result, *ptr); + ptr++; + } + return result; +} + +/** + * Compute a 32-bit checksum for a given data block + * + * @param data Memory address of the data block to be processed. Must be + * 32-bit aligned. + * @param size Size of the data block in bytes. Must be a multiple of 4. + * @return checksum result + */ +inline uint32_t SkComputeChecksum32(const uint32_t* ptr, size_t size) { + SkASSERT(SkIsAlign4(size)); + SkASSERT(SkIsAlign4((intptr_t)ptr)); + + const uint32_t* stop = ptr + (size >> 2); + uint32_t result = 0; + while (ptr < stop) { + SkCHECKSUM_MASH(result, *ptr); + ptr++; + } + return result; +} + class SkChecksum : SkNoncopyable { private: /* |