SH7670 Datasheet, PDF (563/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Section 14 DMAC That Works with Encryption/Decryption and Forward Error Correction Core (A-DMAC)
14.4.3 Checksum
Figure 14.3 shows an example of descriptors that execute only checksum. In figure 14.3, (a) is an
example of continuously allocating checksum descriptors each of which completes one processing
and (b) is an example of splitting processing into several checksum descriptors and allocating the
last checksum descriptor that completes processing.
In the descriptor that performs checksum operation, set the data size in multiples of two bytes.
However, if split descriptors are used, a value other than a multiple of two bytes can be set as the
data size in each descriptor but the total number of data sizes specified in the split descriptors must
be set so that it becomes a multiple of 2. (If processing is split into several descriptors and an odd
size is specified in the non-last descriptor, the A-DMAC waits for the next descriptor without
processing data of the last one byte.)
Rev. 1.00 Nov. 14, 2007 Page 537 of 1262
REJ09B0437-0100