Generic Channels
5-22
5.3.6
Endianism
The endianism of a bus or a memory designates the way data is stored on this
bus or in this memory. There are two types of endianism:
-
Big endian
The MSB of the word is stored at the least address in the memory for a bus.
The MSB of the word is placed on the MSB of the bus.
-
Little endian:
The MSB of the word is stored at the highest address in the memory for a
bus. The MSB of the word is placed on the LSB of the bus.
The internal FIFOs of the system DMA are big endian. All system DMA ports
are treated as little endian on OMAP5910. Therefore, the system DMA con-
tains adaptation logic to convert incoming data to big endian and outgoing data
back to little endian. This adaptation logic is static, can not be configured, and
is transparent to system DMA operation.
Additional logic (unrelated to the system DMA) is available to perform endian-
ism conversion between the DSP and the MPU at the DSP MMU and the MPUI
interfaces. These are described in section 2.11, Endianism Conversion.
The DMA internal FIFOs are big endian.
This adaptation is static and always the same for a given DMA application.
Each DMA port contains an endianism adaptation module.
Figure 5–7. Endianism Adaptation on Transferred Data
Little
endian
memory
Endian
adaptation
Source
port
Channel
FIFO
Big endian
Channel
Endian
adaptation
Destination
port
Little
endian
memory
System DMA
