SH7727 Datasheet, PDF (99/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 2 CPU
The name Ix is the alias for R8. Other aliases are as follows.
Ax0: .REG
Ax1: .REG
Ix: .REG
Ay0: .REG
Ay1: .REG
Iy: .REG
As0: .REG
As1: .REG
As2: .REG
As3: .REG
Is: .REG
(R4)
(R5)
(R8)
(R6)
(R7)
(R9)
(R4) ; This is optional. If you need another alias for single data transfer.
(R5) ; This is optional. If you need another alias for single data transfer.
(R2)
(R3)
(R8) ; This is optional. If you need another alias for single data transfer.
2.1.2 Control Registers
SH7727 has eight control registers: SR, SSR, SPC, GBR, VBR, RS, RE, and MOD (figure 2.5).
SSR, SPC, GBR and VBR are the same as the SH-3 registers. The DSP mode is activated only
when SR.DSP = 1.
Repeat start register RS, repeat end register RE, and repeat counter RC (12-bit part of the SR) and
repeat control bits RF0 and RF1 are new registers and control bits which are used for repeat
control. Modulo register MOD and modulo control bits DMX and DMY in the SR are also new
register and control bits.
In the SR, there are six additional control bits: RC[11:0], RF0, RF1, DMX, DMY and DSP. Bits
DMX, DMY, RC[11:0], and RF[1:0] can be modified in supervisor mode, DSP supervisor mode,
and DSP user mode. The DMX and DMY are used for modulo addressing control. If the DMX is
1 then the modulo addressing mode is effective for the X memory address pointer, Ax (R4 or R5).
If the DMY is 1 then it is effective for the Y memory address pointer, Ay (R6 or R7). However,
both X and Y address pointer cannot be operated under the modulo addressing mode even though
both DMX and DMY bits are set. The case of DMX = DMY = 1 is reserved for future expansion.
When both DMX and DMY are set simultaneously, the hardware will preliminary treat only
address pointer as the modulo addressing mode. Modulo addressing is available for X and Y data
transfer operation (MOVX and MOVY), but not for single data transfer operation (MOVS).
The RF1 and RF0 hold information of the number of repeat steps and they are set when a SETRC
instruction is executed. When RF[1:0] shows 00, the current repeat module consists of one-step
instruction. When RF[1:0] = 01, it means two-step instructions. When RF[1:0] = 11, it means
Rev. 5.00 Dec 12, 2005 page 27 of 1034
REJ09B0254-0500