4.5
Trap Instruction
Trap instruction exception handling starts when a TRAPA instruction is executed. Trap instruction
exception handling can be executed at all times in the program execution state.
The TRAPA instruction fetches a start address from a vector table entry corresponding to a vector
number from 0 to 3, as specified in the instruction code.
Table 4-4 shows the status of CCR and EXR after execution of trap instruction exception
handling.
Table 4-4
Status of CCR and EXR after Trap Instruction Exception Handling
Interrupt Control Mode
0
2
Legend:
1: Set to 1
0: Cleared to 0
—: Retains value prior to execution.
4.6
Stack Status after Exception Handling
Figure 4-4 shows the stack after completion of trap instruction exception handling and interrupt
exception handling.
SP
(a) Interrupt control mode 0
Note: * Ignored on return.
Figure 4-4 Stack Status after Exception Handling (Advanced Modes)
Rev. 5.00, 12/03, page 106 of 1088
CCR
I
1
1
CCR
PC
(24 bits)
UI
I2 to I0
—
—
—
—
SP
(b) Interrupt control mode 2
EXR
T
—
0
EXR
Reserved*
CCR
PC
(24 bits)