SH7727 Datasheet, PDF (122/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 2 CPU
Single Data Addressing: DSP instructions include two single data transfer instructions
(MOVS.W, MOVS.L) that load data into, or store data from, a DSP register. With these
instructions, one of registers R2 to R5 is used as the single data transfer address register (As).
The following four kinds of addressing can be used with single data transfer instructions.
1. Non-update address register addressing:
The As register is an address pointer. It is not updated.
2. Addition index register addressing:
The As register is an address pointer. After a data transfer, the value of the Is register is added
to the As register (post-increment).
3. Increment address register addressing:
The As register is an address pointer. After a data transfer, the As register is incremented by 2
or 4 (post-increment).
4. Decrement address register addressing:
The As register is an address pointer. Before a data transfer, –2 or –4 is added to the As
register (i.e. 2 or 4 is subtracted) (pre-decrement).
The R8 register is the index register (Is) for the address pointer (As). Single data transfer
addressing is shown in figure 2.13.
31
0
R2[As]
31
0
R8[Is]
R3[As]
R4[As]
−2/−4 (DEC)
+2/+4 (INC)
+0 (no update)
R5[As]
ALU
31
MAB
CAB
0
Note: Four address processing methods:
1. No update
2. Index register addition (Is)
3. Increment
4. Decrement
Post-increment
Pre-decrement
Figure 2.13 Single Data Transfer Addressing
Rev. 5.00 Dec 12, 2005 page 50 of 1034
REJ09B0254-0500