SH7727 datasheet(99/1109 Pages) RENESAS

99 / 1109 page

Section 2 CPU

Rev. 5.00 Dec 12, 2005 page 27 of 1034

REJ09B0254-0500

The name Ix is the alias for R8. Other aliases are as follows.

Ax0:

.REG

(R4)

Ax1:

.REG

(R5)

Ix:

.REG

(R8)

Ay0:

.REG

(R6)

Ay1:

.REG

(R7)

Iy:

.REG

(R9)

As0:

.REG

(R4)

;

This is optional. If you need another alias for single data transfer.

As1:

.REG

(R5)

;

This is optional. If you need another alias for single data transfer.

As2:

.REG

(R2)

As3:

.REG

(R3)

Is:

.REG

(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

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

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