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Audio ISA 24-bit audio load
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Author:  banyh [ Thu Feb 20, 2014 1:41 pm ]
Post subject:  Audio ISA 24-bit audio load

在 AndeStar_Audio_ISA_UM012_v1.4 第16頁
為什麼DRJ=0/1讀出來的值會不同?
一個是讀higher 3 bytes,一個是讀lower 3 bytes

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File comment: AndeStar_Audio_ISA_UM012_v1.4 Page 16
2014-02-20_123306.png
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Author:  cindy [ Fri Feb 21, 2014 6:35 pm ]
Post subject:  Re: Audio ISA 24-bit audio load

DRJ means “Destination register Right-Justification”. In 24-bit mode, it tells the 32-bit register file HW the signification part of the register data that a programmer wants to preserve when loading/storing the register data into a 24-bit word local memory since a byte will be dropped. If the local memory is 32-bit word, then no byte will be dropped. But for compatibility with an application developed with 24-bit word local memory in mind, we load data from the high or low 3 bytes based on the DRJ value.

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