DMA enable callback (changes)
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Programmer's DMAManager Reference Manuals
» Part 13 - Hardware Support?DMA callback routines
» DMAManagerDMA enable callback
» DMA callback routines
» DMA enable callback
DMA enable callback
| Entry | |
|---|---|
| R11 | Value of R2 from DMA_QueueTransfer call |
| R12 | Value of R5 from DMA_RegisterChannel call |
| Exit | |
|---|---|
| - | All registers preserved |
| Processor in IRQ or SVC mode |
| IRQ & FIQ status undefined |
Use
DMAManager assumes that the target device will start off with its DMA request line disabled. This call is made just before starting the transfer in the DMA controller, in order to instruct the device driver to enable the DMA request line within the device, or to prepare it for the receipt/transmission of data.
Notes
If DMAManager needs to pause a transfer (e.g. due to memory being moved), the DMA disable callback will be called to disable the DMA request. Once it is safe to resume the transfer this callback will be called again to re-enable it.
This documentation only covers the RISC OS 5 version of the DMAManager SWIs. For other OS versions, consult the appropriate PRM volume (e.g. volume 5a).
See also
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