Datasheet

Chapter 2. ColdFire Core 2-33
Exception Processing Overview
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 2-20. This field records any longword misalignment of the stack pointer that
may have existed when the exception occurred.
• 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 2-21.
• Vector number—This 8-bit field, vector[7–0], defines the exception type. It is
calculated by the processor for internal faults and is supplied by the peripheral for
interrupts. See Table 2-19.
31 28 27 26 25 18 17 16 15 0
A7→ Format FS[3–2] Vector[7–0] FS[1–0] Status Register
+ 0x04 Program Counter [31–0]
Figure 2-1. Exception Stack Frame Form
Table 2-20. Format Field Encoding
Original A7 at Time of
Exception, Bits 1–0
A7 at First Instruction of
Handler
Format Field Bits
31–28
00 Original A[7–8] 0100
01 Original A[7–9] 0101
10 Original A[7–10] 0110
11 Original A[7–11] 0111
Table 2-21. Fault Status Encodings
FS[3–0] Definition
0000 Not an access or address error nor an interrupted debug service routine
0001 Reserved
0010 Interrupt during a debug service routine
0011 Reserved
0100 Error on instruction fetch
0101–011x Reserved
1000 Error on operand write
1001 Attempted write to write-protected space
101x Reserved
1100 Error on operand read
1101–111x Reserved