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#include <asm/asm.h>
#include <asm/mipsregs.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>
.text
.set mips1
.set reorder
.set macro
.set noat
.align 5
# MIPS has 16 exception vectors numbered 0 to 15
# vector number 0 is for interrupts and the others are for various exceptions
# The following code is installed as the handler for exception 0
# There are 8 possible interrupts that can cause this exception.
# The cause register indicates which are pending
# The status register indicates which are enabled
# This code segment basically will decipher which interrup occurred (7 downto 0)
# and pass an integer indicating which was the highest priority pending interrupt
# to the do_IRQ routine.
NESTED(hpIRQ, PT_SIZE, sp)
SAVE_ALL
CLI # Important: mark KERNEL mode !
/*
* Get pending interrupts
*/
mfc0 t0,CP0_CAUSE # get pending interrupts
mfc0 t1,CP0_STATUS # get enabled interrupts
and t0,t1 # isolate allowed ones
andi t0,0xff00 # isolate pending bits
sll t0,16 # shift the pending bits down
beqz t0,3f # no pending intrs, then spurious
nop # delay slot
la a0,7
1: bltz t0,2f # found pending irq
subu a0,1
sll t0,1
b 1b
nop # delay slot
call_do_IRQ:
2: move a1,sp
jal do_IRQ
nop # delay slot
j ret_from_irq
nop
/*
mfc0 t0,CP0_STATUS # disable interrupts
ori t0,1
xori t0,1
mtc0 t0,CP0_STATUS
la a1, ret_from_irq
jr a1
*/
3: j spurious_interrupt
END(hpIRQ)
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