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 Post subject: 軟體處理interrupt stack的說明
PostPosted: Thu Feb 16, 2012 12:32 pm 
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Joined: Fri Mar 04, 2011 9:36 pm
Posts: 500
硬體中斷有數量限制,
如果改成軟體中斷,就可以將發生過的中斷全部存起來。

以下用demo-int做為說明的example。
在demo-int中,當HW1 interrupt發生時,進入的SAVE_ALL_HW macro,
會將interrupt等資訊存起來。

common_ISR_wrapper:
SAVE_ALL_HW
la $r1, ISR_TABLE
lw $r1, [$r1+$r0<<2]
jral $r1
RESTORE_ALL_HW
iret

OS_Trap_Interrupt_HW1:
push $r0
li $r0, 0x01
b common_ISR_wrapper

以下為SAVE_ALL_HW的macro。(在interrupt.h裏)
ir0的bit 1 和2為interrupt level,下面我紅色標示的地方,
為將interrupt level下降1。
粉紅色字體的部份為將interrupt status存入stack

.macro SAVE_ALL_HW !should not touch $r0
/* push caller-saved gpr */
pushm $r1, $r5
pushm $r15, $r30
push_d0d1

#if !(defined(NDS32_BASELINE_V3M) || defined(NDS32_BASELINE_V3))
/* push $INT_MASK */
mfsr $r1, $INT_MASK
push $r1 !push $INT_MASK

/* disable low priority and
* enable high priority interrupt */
ori $r1, $r1, 0x3f ! r1= {mask[31:6],000000}
li $r2, 1
sll $r2, $r2, $r0 ! 1<<r0
subri $r2, $r2, 64 ! 64 - (1 << r0)
sub $r1, $r1, $r2 ! {mask[31:6],000000} - (64- (1<<r0))

mtsr $r1, $INT_MASK

#endif
/* push $PSW, $IPC, $IPSW */
mfsr $r1, $PSW
mfsr $r2, $IPC
mfsr $r3, $IPSW
pushm $r1, $r3


/* You can use -1 if you want to
* descend interrupt level and enable gie or
* you can enable gie when you finish your top
* half isr. */
/* Descend interrupt level */
addi $r1, $r1, #-2
mtsr $r1, $PSW


/* align $sp to 8B boundary */
move $r2, $sp !keep original $sp to be pushed
#if !(defined(NDS32_BASELINE_V3M) || defined(NDS32_BASELINE_V3))
andi $r3, $sp, #4
subri $r3, $r3, #4 ! bit2==0? 4 : 0
sub $sp, $sp, $r3 ! bit2==0? (sp-=4) : (sp-=0)
#endif
push $r2
push_fpu
.endm


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