Page 432 - Programming Microcontrollers in C

Handling Interrupts 417

addu R2,R3\n ldw R2,(R2,0)\n \
jsr R2\n ldm R1-R15,(R0)\n \
addi R0,32\n addi R0,28\n rfi\n”)

void unused_vector(void)
{}

void handler(void)
{

Do_Interrupt();
}
Listing 8-9: Autovector Interrupt Handler
Following the table initialization, there is an assembly language
sequence. This sequence is #defined as the function
Do_Interrupt(), which is called in the interrupt service routine
handler(). The first five assembly instructions clear 120 bytes on
the stack, enough to save the contents of registers 1 through 15, and

Table 8-1 Exception Vector Assignments

Vector Vector Assignment
Number(s) Offset (Hex)
0 000
Reset
1 004 Misaligned access
2 008 Access error
3 00C Divide by zero
4 010 Illegal instruction
5 014 Privilege violation
6 018 Trace exception
7 01C Breakpoint exception
8 020 Unrecoverable error
9 024 Soft reset
10 028 INT autovector
11 02C FINT autovector
12 030 Hardware accelerator
13 034 (Reserved)
14 038
15 03C
16-19 040-04C Trap #0-3 Instruction Vectors
20-31 050-07C Reserved
32-127 080-1FC Reserved for vectored
interrupt controller use