38 lines
1.7 KiB
NASM
38 lines
1.7 KiB
NASM
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;first, clean registers
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;second, load x4002 into a register
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;third, determine if negative or positive
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;fourth depending on what it is, add it to memory location
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;stop when reaching a memory location of zero
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.ORIG x3000 ;start point
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AND R6, R6, #0 ;clean R6
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AND R5, R5, #0 ;clean R5
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AND R4, R4, #0 ;clean R4
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AND R3, R3, #0 ;clean R3
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STI R3, NEGATIVEPOS ;clean memory at location
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STI R3, POSITIVEPOS ;clean memory at location
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LOOP LD R6, POSITION ;load position into register
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ADD R6, R6, #1 ;Add one to register
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ST R6, POSITION ;Store new value in memory
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LDI R3, POSITION ;Load from new value
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ADD R3, R3, #0 ;test for negative
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BRz DONE ;Halt if result is zero
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BRn NEGATIVE ;Branch if negative
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BRp POSITIVE ;branch if positive
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NEGATIVE LDI R4, NEGATIVEPOS ;load negatve total into r4
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ADD R4, R4, R3 ;add stored value together with new value
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STI R4, NEGATIVEPOS ;store the new total back to negative total
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BR LOOP ;loop back
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POSITIVE LDI R5, POSITIVEPOS ;load positive total into r5
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ADD R5, R5, R3 ;add stored value together with nuew value
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STI R5, POSITIVEPOS ;store the new total back into positive total
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BR LOOP ;loop back
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DONE HALT ;kill program
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POSITIVEPOS .fill x4000
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NEGATIVEPOS .fill x4001
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POSITION .fill x4001
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.END
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