SH7014 Datasheet, PDF (101/754 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

5. Exception Processing
5.5 Exceptions Triggered by Instructions
5.5.1 Types of Exceptions Triggered by Instructions
Exception processing can be triggered by trap instructions, general illegal instructions, and illegal
slot instructions, as shown in table 5.8.
Table 5.8 Types of Exceptions Triggered by Instructions
Type
Source Instruction
Trap instructions TRAPA
Illegal slot
instructions
Undefined code placed
immediately after a delayed
branch instruction (delay slot)
and instructions that rewrite the
PC
General illegal
instructions
Undefined code anywhere
besides in a delay slot
Comment
⎯
Delayed branch instructions: JMP, JSR,
BRA, BSR, RTS, RTE, BF/S, BT/S, BSRF,
BRAF
Instructions that rewrite the PC: JMP, JSR,
BRA, BSR, RTS, RTE, BT, BF, TRAPA,
BF/S, BT/S, BSRF, BRAF
⎯
5.5.2 Trap Instructions
When a TRAPA instruction is executed, trap instruction exception processing starts up. The CPU
operates as follows:
1. The status register (SR) is saved to the stack.
2. The program counter (PC) is saved to the stack. The PC value saved is the start address of the
instruction to be executed after the TRAPA instruction.
3. The exception service routine start address is fetched from the exception processing vector
table that corresponds to the vector number specified in the TRAPA instruction. That address
is jumped to and the program starts executing. The jump that occurs is not a delayed branch.
Rev.5.00 Sep. 27, 2007 Page 67 of 716
REJ09B0398-0500