This register provides the Current Descriptor Pointer for the AXI CDMA Scatter Gather Descriptor Management.
Figure 2-4:
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X-Ref Target - Figure 2-4
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Table 2-6: CURDESC_PNTR Register Details
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Bits
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Field Name
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Default Value
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Access Type
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CDMA Mode Used
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Description
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31 to 6
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Current Descriptor Pointer
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0
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R/W
(RO)
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SG
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Current Descriptor Pointer. Indicates the pointer of the current descriptor being worked on. This register must contain a pointer to a valid descriptor prior to writing to the TAILDESC_PTR register. Failure to do so results in an undefined operation by the CDMA.
When the CDMA SG Engine is running (CDMASR.IDLE = 0), the CURDESC_PNTR register is updated by the SG Engine to reflect the starting address of the current descriptor being executed.
On error detection, the CURDESC_PNTR register is updated to reflect the descriptor associated with the detected error.
The register should only be written by the software application when the AXI CDMA is idle (CDMASR.IDLE = 1). Descriptor addresses written to this field must be aligned to 64-byte boundaries (sixteen 32-bit words). Examples are 0x00, 0x40, 0x80. For 64byte alignment bits [5:0] should be 0. Any other alignment has undefined results.
This register is cleared when CDMACR.SGMode = 0.
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5 to 0
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Reserved
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0
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RO
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N/A
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Writing to these bits has no effect and they are always read as zeros.
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Notes:
1.RO = Read Only. Writing has no effect.
2.R/W = Read/Write
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