2.2.4.1.1.2.1.1.2 SHORT_VBAR_CACHE_HIT
The SHORT_VBAR_CACHE_HIT structure is used to specify a Short V-Bar cache hit.
The use of this structure implies that the necessary Short V-Bar data is already present in the Short V-Bar Storage (section 3.3.1.12) ADM element at the index specified by the shortVBarIndex field. In this case, the shortVBarPixels field of the encapsulating CLEARCODEC_VBAR (section 2.2.4.1.1.2.1.1) structure MUST NOT be present, and the size of the data in the Short V-Bar Storage ADM element MUST NOT exceed 3 * (yEnd - yStart + 1 - shortVBarYOn) bytes, where yEnd and yStart are specified in the encapsulating CLEARCODEC_BAND (section 2.2.4.1.1.2.1) structure.
As part of processing this header, each pixel position in the V-Bar Storage ADM element at the V-Bar Storage Cursor (section 3.3.1.11) ADM element MUST be updated using the data in the Short V-Bar Storage ADM element. The number of pixels placed into the V-Bar Storage ADM element MUST equal yEnd – yStart + 1. For each position y within the V-Bar, the pixels MUST be updated as follows:
If y < shortVBarYOn, then use the blueBkg, greenBKg, and redBkg values specified in the encapsulating CLEARCODEC_BAND structure
If y >= shortVBarYOn and y < shortVBarYOn + Short V-Bar pixel count, then use the color found in the Short V-Bar Storage ADM element at pixel position y – shortVBarYOn
If y >= shortVBarYOn + Short V-Bar pixel count, then use the blueBkg, greenBKg, and redBkg values specified in the encapsulating CLEARCODEC_BAND structure
The V-Bar Storage Cursor (section 3.3.1.11) ADM element MUST be incremented by 1 and MUST wrap to zero when incremented from 32767.
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shortVBarIndex |
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shortVBarYOn |
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shortVBarIndex (14 bits): A 14-bit unsigned integer that specifies the position in the Short V-Bar Storage ADM element for the current Short V-Bar.
x (2 bits): A 2-bit unsigned integer that MUST be set to 0x1.
shortVBarYOn (8 bits): An 8-bit unsigned integer that specifies where the Short V-Bar begins, expressed as an offset from the top of the V-Bar.