HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 125

• Manufacturer Part Number: HD6417660
• Description: Renesas 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

• Example 7: Repeat loop consisting of two instructions (extended to the instruction stream
• Example 8: Repeat loop consisting of one instruction instructions (extended to the instruction
In the DSP mode, the system control instructions (LDC and STC) that handle the RS and RE
registers are extended. The RC[11:0] bits and RF[1:0] bits of the SR can be controlled by the
LDC and STC instructions for the SR register. These instructions should be used if an exception
is enabled during repeat loop execution. The repeat loop can be resumed correctly by storing the
RS and RE register values and RC[11:0] bits and RF[1:0] bits of the SR register before exception
handling and by restoring the stored values after exception handling. However, note that there are
some restrictions on exception acceptance during repeat loop execution. For details refer to section
3.3.1 (3), Restrictions on Repeat Loop Control and section 4, Exception Handling.
Table 3.6
Instruction
STC RS, Rn
STC RE, Rn
STC.L RS, @-Rn
STC.L RE, @-Rn
LDC.L @Rn+, RS
LDC.L @Rn+, RE
LDC Rn,RS
LDC Rn, RE
RptStart: instr1
RptEnd:
RptStart:
RptEnd:
shown in example 3, above)
stream shown in example 3, above)
DSP Mode Extended System Control Instructions
REPEAT RptStart, RptEnd, #4
instr0
instr2
REPEAT RptStart, RptEnd, #4
instr0
instr1
Operation
RS→Rn
RE→Rn
Rn-4→Rn, RS→(Rn)
Rn-4→Rn, RE→(Rn)
(Rn)→RS, Rn+4→Rn
(Rn)→RE, Rn+4→Rn
Rn→RS
Rn→RE
; [Repeat detection instruction]
; [Repeat start instruction]
; [Repeat end instruction]
; [Repeat detection instruction]
; [Repeat start instruction] ==
[Repeat end instruction]
Number of Execution States
1
1
1
1
4
4
4
4
Rev. 1.00, 02/04, page 87 of 804