SH7616 datasheet(85/935 Pages) RENESAS

85 / 935 page

Section 2 CPU

Rev. 2.00 Mar 09, 2006 page 59 of 906

REJ09B0292-0200

Modulo Addressing: The chip has a modulo addressing mode, just as other DSPs do. Address

registers are updated in the same manner as with other modes. When the address pointer value

becomes the same as a previously established modulo end address, the address pointer becomes

the modulo start address.

Modulo addressing is valid only with X, Y data transfer instructions (MOVX.W, MOVY.W).

When the DMX bit of the SR register is set, the X address register enters modulo addressing

mode; when the DMY bit of the SR register is set, the Y address register does so. Modulo

addressing is valid only for either the X or the Y address register; it is not possible to make them

both modulo addressing mode at the same time. Therefore, do not simultaneously set the DMX

and DMY. If they happen to be set at the same time, only the DMY side is valid.

The MOD register is used to designate the start and end addresses of the modulo address area; it

stores the MS (modulo start) and ME (modulo end). An example of MOD register (MS, ME)

usage is indicated below.

MOV.L ModAddr,Rn;

Rn=ModEnd, ModStart

LDC Rn,MOD;

ME=ModEnd, MS=ModStart

ModAddr:

.DATA.W

mEnd;

ModEnd

.DATA.W

mStart;

ModStart

ModStart: .DATA

ModEnd:

.DATA

Designate the start and end addresses in MS and ME, and then set the DMX or DMY bit to 1. The

contents of the address register are compared with ME. If they match ME, the start address MS is

stored in the address register. The lower 16 bits of the address register are compared with ME. The

maximum modulo size is 64 kbytes. This is sufficient for X, Y data memory accesses. Figure 2.11

shows a block diagram of modulo addressing.

SH7616 Datasheet(PDF) 85 Page - Renesas Technology Corp