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# Interrupt Start                                                              #

#------------------------------------------------------------------------------#

        # .ent  intr_handler

# intr_handler:

        # .set  noreorder

        # .set  noat

# If we do not include the Interrupt API, simply return to normal execution

# immediately.

# .ifdef _INTERRUPT

        # addiu $sp, $sp, -72            # Allocate space for all relevant registers.

        # sw       $at,  4($sp)            # Save all registers, that are used directily

        # sw       $v0,  8($sp)            # after a successful execution of the interrupt

        # sw       $v1, 12($sp)            # service routines.

        # sw       $a0, 16($sp)            # Registers $s0 - $s8 do not need to be saved,

        # sw       $a1, 20($sp)            # since the compiler stores them if they are

        # sw       $a2, 24($sp)            # used in a procedure.

        # sw       $a3, 28($sp)            # $gp is the same for the entire source code.

        # sw       $t0, 32($sp)            # Registers $k0 and $k1 are reserved for ASM

        # sw       $t1, 36($sp)            # routines. The C compiler does not use them.

        # sw       $t2, 40($sp)

        # sw       $t3, 44($sp)

        # sw       $t4, 48($sp)

        # sw       $t5, 52($sp)

        # sw       $t6, 56($sp)

        # sw       $t7, 60($sp)

        # sw       $t8, 64($sp)

        # sw       $t9, 68($sp)

        # sw       $ra, 72($sp)

        # mfc0  $k0, $13                            # Retrieve CAUSE (Pending Interrupts).

        #nop

        # mfc0  $k1, $12                            # Retrieve SR (Interrupt mask and global IE).

        # nop

        # and   $k0, $k0, $k1            # Get legal pending interrupts.

        # addiu $sp, $sp, -24

        # jal   intr_dispatch           # Jump to C interrupt dispatch routine.

   # srl        $a0, $k0, 8

   # addiu $sp, $sp, 24

        # lw       $at,  4($sp)            # Restore saved registers.

        # lw       $v0,  8($sp)

        # lw       $v1, 12($sp)

        # lw       $a0, 16($sp)

        # lw       $a1, 20($sp)

        # lw       $a2, 24($sp)

        # lw       $a3, 28($sp)

        # lw       $t0, 32($sp)

        # lw       $t1, 36($sp)

        # lw       $t2, 40($sp)

        # lw       $t3, 44($sp)

        # lw       $t4, 48($sp)

        # lw       $t5, 52($sp)

        # lw       $t6, 56($sp)

        # lw       $t7, 60($sp)

        # lw       $t8, 64($sp)

        # lw       $t9, 68($sp)

        # lw       $ra, 72($sp)

        # addiu $sp, $sp, 72          # Undo stack allocation.

# .endif

        # mfc0  $k1, $14                            # Retrieve EPC

        # nop

        # jr       $k1                     # Return to normal execution.

        # rfe                                     # Restore from exception. Pop IE stack.

   # .set  at

        # .set  reorder

        # .end  intr_handler

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