SH7206 Datasheet, PDF (128/1188 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7200 Series

Section 4 Exception Handling
4.6.2 Trap Instructions
When a TRAPA instruction is executed, trap instruction exception handling starts. The CPU
operates as follows:
1. The exception service routine start address which corresponds to the vector number specified
in the TRAPA instruction is fetched from the exception handling vector table.
2. The status register (SR) is saved to the stack.
3. 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.
4. After jumping to the exception service routine start address fetched from the exception
handling vector table, program execution starts. The jump that occurs is not a delayed branch.
4.6.3 Slot Illegal Instructions
An instruction placed immediately after a delayed branch instruction is said to be placed in a delay
slot. When the instruction placed in the delay slot is undefined code, an instruction that rewrites
the PC, a 32-bit instruction, an RESBANK instruction, a DIVS instruction, or a DIVU instruction,
slot illegal exception handling starts when such kind of instruction is decoded. The CPU operates
as follows:
1. The exception service routine start address is fetched from the exception handling vector table.
2. The status register (SR) is saved to the stack.
3. The program counter (PC) is saved to the stack. The PC value saved is the jump address of the
delayed branch instruction immediately before the undefined code, the instruction that rewrites
the PC, the 32-bit instruction, the RESBANK instruction, the DIVS instruction, or the DIVU
instruction.
4. After jumping to the exception service routine start address fetched from the exception
handling vector table, program execution starts. The jump that occurs is not a delayed branch.
4.6.4 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 handling starts. The CPU
handles general illegal instructions in the same way as slot illegal instructions. Unlike processing
of slot illegal instructions, however, the program counter value stored is the start address of the
undefined code.
Rev. 3.00 Jun. 18, 2008 Page 104 of 1160
REJ09B0191-0300