Exception Vector Assignments - Motorola ColdFire MCF5281 User Manual

Third, the processor saves the current context by creating an exception stack frame on the
supervisor system stack. As a result, the exception stack frame is created at a 0-modulo-4
address on the top of the current system stack. Additionally, the processor uses a simplified
fixed-length stack frame for all exceptions. The exception type determines whether the
program counter placed in the exception stack frame defines the location of the faulting
instruction (fault) or the address of the next instruction to be executed (next).
Fourth, the processor calculates the address of the first instruction of the exception handler.
By definition, the exception vector table is aligned on a 1 Mbyte boundary. This instruction
address is generated by fetching an exception vector from the table located at the address
defined in the vector base register. The index into the exception table is calculated as (4 x
vector number). Once the exception vector has been fetched, the contents of the vector
determine the address of the first instruction of the desired handler. After the instruction
fetch for the first opcode of the handler has been initiated, exception processing terminates
and normal instruction processing continues in the handler.
All ColdFire processors support a 1024-byte vector table aligned on any 1 Mbyte address
boundary (see Table 2-5). The table contains 256 exception vectors; the first 64 are defined
by Motorola and the remaining 192 are user-defined interrupt vectors.
Vector
Number(S)
0
1
2
3
4
5
6–7
8
9
10
11
12
13
14
15–23
24
25–31
32–47
48–63
MOTOROLA
Table 2-5. Exception Vector Assignments
Stacked
Vector
Program
Offset (Hex)
Counter
0x000
0x004
0x008
0x00C
0x010
0x014
0x018–0x01C
0x020
0x024
0x028
0x02C
0x030
0x034
0x038
0x03C–0x05C
0x060
0x064-0x07C
0x080–0x0BC
0x0C0–0x0FC
Chapter 2. ColdFire Core
Assignment
— Initial stack pointer
— Initial program counter
Fault Access error
Fault Address error
Fault Illegal instruction
Fault Divide by zero
— Reserved
Fault Privilege violation
Next Trace
Fault Unimplemented line-a opcode
Fault Unimplemented line-f opcode
Next Debug interrupt
— Reserved
Fault Format error
— Reserved
Next Spurious interrupt
— Reserved
Next Trap # 0-15 instructions
— Reserved
Exception Processing Overview
2-11