DMA_TerminateTransfer

DMAManager

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» DMA_TerminateTransfer

DMA_TerminateTransfer

(SWI &46143)

Use

This SWI is used to terminate a DMA transfer originally queued by DMA_QueueTransfer.

Notes

Before a transfer is terminated, the following steps are followed:

• If the transfer is active:
  • DMAManager will stop the transfer within the DMA controller
  • The DMA disable callback will be called (to allow the device to de-assert its DMA request line)
• The transfer will be removed from the queue associated with the logical channel, allowing the transfer behind it to start as necessary.
  • If the transfer was blocking the logical channel (i.e. the transfer had previously been suspended by DMA_SuspendTransfer with bit 0 of R0 clear) then the channel will be un-blocked and will resume processing its transfer queue
• The DMA completed callback will be called, with V set and R0 containing a pointer to the supplied error block

An error block is returned if the DMA tag is invalid.

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

• DMA_QueueTransfer
• DMA_SuspendTransfer