SH7108 Datasheet, PDF (103/560 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

Section 5 Exception Processing
5.5.4 General Illegal Instructions
When undefined code placed anywhere other than immediately after a delayed branch instruction
(i.e., in a delay slot) is decoded, general illegal instruction exception processing starts. The CPU
handles the general illegal instructions in the same procedures as in the illegal slot instructions.
Unlike processing of illegal slot instructions, however, the program counter value that is stacked is
the start address of the undefined code.
5.6 Cases when Exception Sources Are Not Accepted
When an address error or interrupt is generated directly after a delayed branch instruction or
interrupt-disabled instruction, it is sometimes not accepted immediately but stored instead, as
shown in table 5.10. In this case, it will be accepted when an instruction that can accept the
exception is decoded.
Table 5.10 Generation of Exception Sources Immediately after a Delayed Branch
Instruction or Interrupt-Disabled Instruction
Exception Source
Point of Occurrence
Address Error
Interrupt
Immediately after a delayed branch instruction*¹
Immediately after an interrupt-disabled instruction*²
Not accepted
Accepted
Not accepted
Not accepted
Notes: 1. Delayed branch instructions: JMP, JSR, BRA, BSR, RTS, RTE, BF/S, BT/S, BSRF, and
BRAF
2. Interrupt-disabled instructions: LDC, LDC.L, STC, STC.L, LDS, LDS.L, STS, and STS.L
5.6.1 Immediately after a Delayed Branch Instruction
When an instruction placed immediately after a delayed branch instruction (delay slot) is decoded,
neither address errors nor interrupts are accepted. The delayed branch instruction and the
instruction placed immediately after it (delay slot) are always executed consecutively, so no
exception processing occurs during this period.
5.6.2 Immediately after an Interrupt-Disabled Instruction
When an instruction placed immediately after an interrupt-disabled instruction is decoded,
interrupts are not accepted. Address errors can be accepted.
Rev.1.00 Sep. 18, 2008 Page 69 of 522
REJ09B0069-0100