#  proj5.asm
#
#  Written by:  Justin and Victor
#
#
#  Demonstrate how the mips cpu handles an exception and its return
#
#  Notes:
#   1.  Command: xspim -noexception proj5.asm
#   2.  You must use the label __start

.globl __start

.data
bignum:   .word     0x40000000
String:   .space    9
exaddr:   .asciiz   "\nException at 0x"
exnum:    .asciiz   "\n  Exception number: "
nl:   .asciiz   "\n"

# exception handler must be in kernel space at this exact address
.ktext 0x80000180

# do whatever and then return control to program
exception_handler:

# analyze program and then
# fix $t9 for programmer
# in this case, programmer had one extra zero in bignum
# ...
# move EPC into a register (shown as an example of mfc0 use)
  la   $a0, exaddr
  li   $v0, 4
  syscall
  mfc0 $s1, $14
  add  $v0, $s1, $0
  la   $a0, String
  jal  h2a
  li   $v0, 4
  syscall
  la $a0, exnum
  syscall