Exception Stack Frame - Motorola MC68030 User Manual

Processing States

4.3.2 Exception Stack Frame

Exception processing saves the most volatile portion of the current processor context on the
top of the supervisor stack. This context is organized in a format called the exception stack
frame. This information always includes a copy of the status register, the program counter,
the vector offset of the vector, and the frame format field. The frame format field identifies
the type of stack frame. The RTE instruction uses the value in the format field to properly
restore the information stored in the stack frame and to deallocate the stack space. The
general form of the exception stack frame is illustrated in Figure 4-1. Refer to Section 8
Exception Processing for a complete list of exception stack frames.
15 12 0
SP
STATUS REGISTER
PROGRAM COUNTER
FORMAT VECTOR OFFSET
ADDITIONAL PROCESSOR STATE INFORMATION
(2, 6, 12, OR 42 WORDS, IF NEEDED)
Figure 4-1. General Exception Stack Frame
MOTOROLA MC68030 USER'S MANUAL 4-7