33 lines
733 B
ArmAsm
33 lines
733 B
ArmAsm
.define Pro
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.sect .text
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.sect .rom
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.sect .data
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.sect .bss
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.sect .text
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! This routine is called at the entry of a procedure.
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! It saves the localbase of the invoking procedure, and sets the
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! new localbase to the present value of the stackpointer.
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! It then initializes the second localbase by subtracting
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! BASE from the real one.
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Pro:
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ldx LB ! get localbase (lowbyte)
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lda LB+1 ! get localbase (highbyte)
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jsr Push ! push localbase onto the stack
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ldx SP+2 ! get stackpointer (lowbyte)
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lda SP+1 ! get stackpointer (highbyte)
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stx LB ! new localbase (lowbyte)
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sta LB+1 ! new localbse (highbyte)
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tay
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txa
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sec
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sbc #BASE
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sta LBl ! second localbase (lowbyte)
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tya
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sbc #0
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sta LBl+1 ! second localbase (highbyte)
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rts
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