SH7713 datasheet(127/904 Pages) RENESAS

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Section 3 DSP Operating Unit

Rev.1.50 Aug. 30, 2006 Page 87 of 860

REJ09B0288-0150

If RC[11:0]

≥ 2, the program counter (PC) value is not correct for instructions two instructions

following a repeat detection instruction. In a repeat loop consisting of one to three instructions,

the PC indicates the correct value (instruction address + 4) for an instruction (repeat start

instruction) following a repeat detection instruction but the PC continues to indicate the same

address (repeat start instruction address) from the subsequent instruction to a repeat end

instruction. In a repeat loop consisting of four or more instructions, the PC indicates the correct

value (instruction address + 4) for an instruction following a repeat detec-tion instruction, but

PC indicates the RS and (RS +2) for instructions two and three instructions following the

repeat detection instruction. Here, RS indicates the value stored in the repeat start register

(RS). The correct operation cannot be guaranteed for the incorrect PC values.

Accordingly, PC relative addressing instructions placed two or more instructions following the

repeat detection instruction cannot be executed correctly and the correct results cannot be

obtained.

 PC relative addressing instructions

MOVA @(disp, PC), Rn

MOV.W @(disp, PC), Rn

MOV.L @(disp, PC), Rn

(Including the case when the MOV #imm,Rn is extended to MOV.W @(disp, PC), Rn or

MOV.L @(disp, PC), Rn)

Table 3.7

PC Value during Repeat Control (When RC[11:0]

≥ 2)

Number of Instructions in Repeat Loop

≥ 4

RptDtct

RptDtct + 4

RptDtct +4

RptDtct1 RptDtct1 + 4

RptDtct1 + 4

RptDtct2



RptDtct1 + 4

RptDtct3



RptDtct1 + 4

RS + 2

Note:

In table 3.7, the following labels are used.

RptDtct:

An address of the repeat detection instruction

RptDtct1:

An address of the instruction one instruction following the repeat start

instruction (In a repeat loop consisting of one to three instructions, RptStart is

a repeat start instruction)

RptDtct2:

An address of the instruction two instruction following the repeat start

instruction

RptDtct3:

An address of the instruction three instruction following the repeat start

instruction

7. Repeat counter and repeat control

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