SH7710 Datasheet, PDF (129/996 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series

Section 3 DSP Operating Unit
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
1
2
3
≥4
RptDtct RptDtct + 4
RptDtct + 4
RptDtct + 4
RptDtct +4
RptDtct1 RptDtct1 + 4
RptDtct1 + 4
RptDtct1 + 4
RptDtct1 + 4
RptDtct2 
RptDtct1 + 4
RptDtct1 + 4
RS
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
Rev. 2.00 Dec. 07, 2005 Page 87 of 950
REJ09B0079-0200