2.8.3 HashCode10Atom
Referenced by: PP10SlideBinaryTagExtension
An atom record that specifies the hash code for the animation information for a slide.
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rh (8 bytes): A RecordHeader structure (section 2.3.1) that specifies the header for this record. Sub-fields are further specified in the following table.
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Field
Meaning
rh.recVer
MUST be 0x0.
rh.recInstance
MUST be 0x000.
rh.recType
MUST be RT_HashCodeAtom.
rh.recLen
MUST be 0x00000004.
hash (4 bytes): An unsigned integer that specifies a hash value for the animation information of all shapes in a slide. To calculate the hash value, a random array MUST be initialized first, as specified in the following pseudocode:
§ Define randomArray as an array of 256 rows and 256 columns
§ Initialize all elements of randomArray with 0x00000000
§ Set randomSeed to 0x00000001
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§ FOR each row of randomArray
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§ FOR each column of randomArray
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§ Set r0 to randomSeed
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§ Set r1 to ((r0 * 0x000343FD + 0x00269EC3) >> 16) & 0x00007FFF
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§ Set r2 to ((r1 * 0x000343FD + 0x00269EC3) >> 16) & 0x00007FFF
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§ Set r3 to ((r2 * 0x000343FD + 0x00269EC3) >> 16) & 0x00007FFF
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§ Set r4 to ((r3 * 0x000343FD + 0x00269EC3) >> 16) & 0x00007FFF
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§ Set randomSeed to r4
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§ Set r1 to (r1 % 0x00000100)
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§ Set r2 to (r2 % 0x00000100) << 8
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§ Set r3 to (r3 % 0x00000100) << 16
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§ Set r4 to (r4 % 0x00000100) << 24
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§ Set randomArray position (row, column) to r4 | r3 | r2 | r1
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§ END FOR
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§ END FOR
Then, the random array can be used to calculate hash values for all slides, as specified in the following pseudocode:
§ Set hash to 0x00000000
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§ FOR each shape in the slide
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§ Define animInfoAtom as AnimationInfoAtom
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§ Initialize all bytes of animInfoAtom with zero
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§ IF AnimationInfoAtom exists in the shape THEN
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§ Read the animation information into animInfoAtom
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§ END IF
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§ Set shapeId to identifier of the shape
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§ FOR each byte in animInfoAtom
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§ Set byteIndex to the index of the byte in animInfoAtom
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§ Set rowIndex to (shapeId * (byteIndex + 1)) % 256
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§ Set hash to hash ^ randomArray[rowIndex][byte]
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§ END FOR
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§ END FOR