DMA-scatter and gather operations for non-contiguous memory
A direct memory access (DMA) controller, includes circuitry configured to load a DMA transfer descriptor configured to define which memory elements within a contiguous block of n memory elements are to be included in a given DMA transfer. The circuitry is further configured to, based on the DMA transfer descriptor, determine whether each memory element within the contiguous block of n memory elements is to be included in the given DMA transfer, including a determination that two or more non-contiguous sub-blocks of memory elements within the contiguous block of n memory elements are to be transferred. The circuitry is further configured to, based on the determination of whether each memory element within the contiguous block of n memory elements is to be included in the given DMA transfer, perform the DMA transfer of memory elements determined to be included within the given DMA transfer.
1. A direct memory access (DMA) controller, including circuitry configured to:
load a first DMA transfer descriptor, the first DMA transfer descriptor configured to define which memory elements within a first contiguous block of n memory elements are to be included in a given DMA transfer;
based on the first DMA transfer descriptor, determine whether each memory element within the first contiguous block of n memory elements is to be included in the given DMA transfer, including a determination that a plurality of non-contiguous sub-blocks of memory elements within the first contiguous block of n memory elements are to be transferred; and
based on the determination of whether each memory element within the first contiguous block of n memory elements is to be included in the given DMA transfer, perform the DMA transfer of memory elements determined to be included within the given DMA transfer.
2. The DMA controller of claim 1 , wherein the circuitry is further configured to:
determine that additional memory elements are to be included in the given DMA transfer;
load a second DMA transfer descriptor, the second DMA transfer descriptor configured to define which memory elements within a second contiguous block of n memory elements are to be included in a given DMA transfer;
based on the second DMA transfer descriptor, determine whether each memory element within the second contiguous block of n memory elements is to be included in the given DMA transfer, including a determination that a plurality of non-contiguous sub-blocks of memory elements within the second contiguous block of n memory elements are to be transferred; and
based on the determination of whether each memory element within the second contiguous block of n memory elements is to be included in the given DMA transfer, perform the DMA transfer of memory elements determined to be included within the given DMA transfer.
3. The DMA controller of claim 2 , wherein the circuitry is further configured to determine that additional memory elements are to be included in the given DMA transfer from information included in the first DMA transfer descriptor.
4. The DMA controller of claim 2 , wherein the circuitry is further configured to determine an address of the second DMA transfer descriptor from information included in the first DMA transfer descriptor.
5. The DMA controller of claim 2 , wherein the first and second contiguous blocks of n memory elements to be included in the given DMA transfer are within a same peripheral.
6. The DMA controller of claim 2 , wherein the first and second contiguous blocks of n memory elements to be included in the given DMA transfer are within a different peripheral.
7. The DMA controller of claim 2 , wherein the first DMA transfer descriptor is configured to define all of the plurality of non-contiguous sub-blocks within the first contiguous block of n memory elements are to be transferred.
8. The DMA controller of claim 1 , wherein the first DMA transfer descriptor is further configured to define the plurality of non-contiguous sub-blocks of memory elements within the first contiguous block of n memory elements.
9. The DMA controller of claim 8 , wherein the first DMA transfer descriptor is further configured to define a first memory element within the first contiguous block of n memory elements to be included in the given DMA transfer by a base address of the first contiguous block of n memory elements.
10. The DMA controller of claim 8 , wherein the first DMA transfer descriptor is further configured to define one or more second memory elements within the first contiguous block of n memory elements to be included in the given DMA transfer by a plurality of indicators.
11. The DMA controller of claim 10 , wherein the plurality of indicators includes a series of bits, each bit configured to indicate whether an associated memory element is to be included in the given DMA transfer.
12. The DMA controller of claim 11 , wherein the series of bits includes n bits.
13. The DMA controller of claim 12 , wherein one of the n bits is configured to indicate that additional memory elements are to be included in the given DMA transfer.
14. The DMA controller of claim 1 , wherein the first contiguous block of n memory elements to be included in the given DMA transfer is within a register bank and the first contiguous block of n memory elements to be included in the given DMA transfer has a different base address than the register bank.
15. A method for direct memory access (DMA) control, including:
loading a first DMA transfer descriptor, the first DMA transfer descriptor defining which memory elements within a first contiguous block of n memory elements are to be included in a given DMA transfer;
based on the first DMA transfer descriptor, determining whether each memory element within the first contiguous block of n memory elements is to be included in the given DMA transfer, including a determination that a plurality of non-contiguous sub-blocks of memory elements within the first contiguous block of n memory elements are to be transferred; and
based on the determination of whether each memory element within the first contiguous block of n memory elements is to be included in the given DMA transfer, performing the DMA transfer of memory elements determined to be included within the given DMA transfer.
16. The method of claim 15 , further comprising:
determining that additional memory elements are to be included in the given DMA transfer;
loading a second DMA transfer descriptor, the second DMA transfer descriptor configured to define which memory elements within a second contiguous block of n memory elements are to be included in a given DMA transfer;
based on the second DMA transfer descriptor, determining whether each memory element within the second contiguous block of n memory elements is to be included in the given DMA transfer, including a determination that a plurality of non-contiguous sub-blocks of memory elements within the second contiguous block of n memory elements are to be transferred; and
based on the determination of whether each memory element within the second contiguous block of n memory elements is to be included in the given DMA transfer, performing the DMA transfer of memory elements determined to be included within the given DMA transfer.
17. The method of claim 16 , further comprising determining that additional memory elements are to be included in the given DMA transfer from information included in the first DMA transfer descriptor.
18. The method of claim 16 , further comprising determining an address of the second DMA transfer descriptor from information included in the first DMA transfer descriptor.
19. The method of claim 16 , further comprising, defining, in the first DMA transfer descriptor, all of the plurality of non-contiguous sub-blocks within the first contiguous block of n memory elements are to be transferred.
20. The method of claim 15 , further comprising, wherein the first DMA transfer descriptor is further configured to define the plurality of non-contiguous sub-blocks of memory elements within the first contiguous block of n memory elements.