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C–– Efficiency
5-42
change is the table of interrupt vectors. At the top of the file is a list of interrupt
labels. The ones that are not used are commented out with a semicolon.
; external DAC_ISR
; external timer1_isr
external timer2_isr
; external pd2
; external pd3
; external portF
; external pd4
; external pd5
At the bottom of the file are a dummy interrupt routine and the interrupt vector table.
pd2
pd3
portF
pd4
pd5
DAC_ISR
timer1_isr
;timer2_isr
nop
INTE
iret
AORG 07F00h
DATA _EQ,_NE,_LT,_LE,_GE,_GT,_ULT,_ULE,_UGE,_UGT,_LNEG
DATA _EQS,_NES,_LTS,_LES,_GES,_GTS,_ULTS,_ULES,_UGES,_UGTS
DATA _DIV,_DIVU,_EXTB,_ASR
AORG 07FF0h
data DAC_ISR ; the DAC interrupt is used for synthesis
data timer1_isr ; this is the timer1 isr.
data timer2_isr ; this is the timer2 isr.
data pd2
data pd3
data portF
data pd4
data pd5
aorg 0x7ffe
data 0x1ffff ;ROM protection word (0x7ffe)
data init614 ;reset address (0x7fff)
Notice that timer2 was not commented out at the top of the file but it is
commented out in the dummy interrupt routine. External interrupt routines are
switched on by not commenting them at the external statement at the top of
the file and commenting them in the dummy interrupt routine. They are
switched off by commenting their external statement at the top and not
commenting the label in the dummy routine at the bottom. Note that this does
not enable or disable an interrupt, it just controls what is executed when it fires.
Interrupt routines will be enabled and disabled in the next file, but it is important
to provide a dummy routine for unused interrupts in case a programming error
causes them to be accidentally enabled.