SH7721 datasheet(299/1524 Pages) RENESAS

299 / 1524 page

Section 7 Exception Handling

Rev. 3.00 Jan. 18, 2008 Page 237 of 1458

REJ09B0033-0300

(1)

SPC Saved by an Exception in Repeat Control Period

If an exception is accepted in the repeat control period while the repeat counter (RC[11:0]) in the

SR register is two or greater, the program counter to be saved may not indicate the value to be

returned correctly. To execute the repeat control after returning from an exception processing, the

return address must indicate an instruction prior to a repeat detection instruction. Accordingly, if

an exception is accepted in repeat control period, an exception other than re-execution type

exception by a repeat detection instruction cannot return to the repeat control correctly.

Table 7.3

SPC Value When a Re-Execution Type Exception Occurs in Repeat Control

(SR.RC[11:0]

≥2)

Number of Instructions in a Repeat Loop

Instruction Where an

Exception Occurs

4 or Greater

RptDtct

RptDtct1

RptDtct2



RptDtct1

RS-4

RptDtct3



RptDtct1

RS-2

Note:

The following labels are used here.

RptDtct:

Repeat detection instruction address

RptDtct1: Instruction address immediately after the repeat detect instruction

RptDtct2: Second instruction address from the repeat detect instruction

RptDtct3: Third instruction address from the repeat detect instruction

RS:

Repeat start instruction address

If a re-execution type exception is accepted at an instruction in the hatched areas above, a

return address to be saved in the SPC is incorrect. If SR.RC[11:0] is 1 or 0, a correct return

address is saved in the SPC.

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