SH7713 datasheet(125/904 Pages) RENESAS

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Section 3 DSP Operating Unit

Rev.1.50 Aug. 30, 2006 Page 85 of 860

REJ09B0288-0150

Restrictions on Repeat Loop Control

1. Repeat control instruction assignment

The SETRC instruction must be executed after executing the LDRS and LDRE instructions. In

addition, note that at least one instruction is required between the SETRC instruction and a

repeat start instruction.

2. Illegal instruction one or more instructions following the repeat detection instruction

If one of the following instructions is executed between an instruction following a repeat

detection instruction to a repeat end instruction, an illegal instruction exception occurs.

 Branch instructions

BRA, BSR, BT, BF, BT/F, BF/S, BSRF, RTS, BRAF, RTE, JSR, JMP, TRAPA

 Repeat control instructions

SETRC, LDRS, LDRE

 Load instructions for SR, RS, and RE registers

LDC Rn,SR, LDC @Rn+,SR, LDC Rn,RE, LDC @Rn+,RE, LDC Rn,RS, LDC @Rn+,RS

Note:

This restriction applies to all instructions for a repeat loop consisting of one to three

instructions and to three instructions including a repeat end instruction for a repeat loop

consisting of four or more instructions.

3. Instructions prohibited during repeat loop (In a repeat loop consisting of four or more

instructions)

The following instructions must not be placed between the repeat start instruction and repeat

detection instruction in a repeat loop consisting of four or more instructions. Otherwise, the

correct operation cannot be guaranteed.

 Repeat control instructions

SETRC, LDRS, LDRE

 Load instructions for SR, RS, and RE registers

LDC Rn,SR, LDC @Rn+,SR, LDC Rn,RE, LDC @Rn+,RE, LDC Rn,RS, LDC @Rn+,RS

Note:

Multiple repeat loops cannot be guaranteed. Describe the inner loop by repeat control

instructions, and the external loop by other instructions such as DT or BF/S.

4. Restriction on branching to an instruction following the repeat detection instruction and an

exception acceptance

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