Motorola DigitalDNA ColdFire MCF5272 User Manual page 86

Exception Processing Overview
2.8.1 Exception Stack Frame Definition
The exception stack frame is shown in Figure 2-10. The first longword of the exception
stack frame contains the 16-bit format/vector word (F/V) and the 16-bit status register. The
second longword contains the 32-bit program counter address.
31 28
A7→ Format
+ 0x04
The 16-bit format/vector word contains three unique fields:
• Format field—This 4-bit field at the top of the system stack is always written with a
value of {4,5,6,7} by the processor indicating a 2-longword frame format. See
Table 2-19. This field records any longword misalignment of the stack pointer that
may have existed when the exception occurred.
Original A7 at Time of
Exception, Bits 1–0
• Fault status field—The 4-bit field, FS[3–0], at the top of the system stack is defined
for access and address errors along with interrupted debug service routines. See
Table 2-20.
FS[3–0]
0000-001x
0100
0101–011x
1000
1001
101x
1100
1101–111x
2-38
27 26 25 18
FS[3–2] Vector[7–0]
Program Counter [31–0]
Figure 2-10. Exception Stack Frame Form
Table 2-19. Format Field Encoding
A7 at First Instruction of
00
01
10
11
Table 2-20. Fault Status Encodings
Reserved
Error on instruction fetch
Reserved
Error on operand write
Attempted write to write-protected space
Reserved
Error on operand read
Reserved
MCF5272 User's Manual
17 16 15
FS[1–0]
Handler
Original A[7–8]
Original A[7–9]
Original A[7–10]
Original A[7–11]
Definition
Status Register
Format Field Bits
31–28
0100
0101
0110
0111
0