46 lines
1.6 KiB
NASM
46 lines
1.6 KiB
NASM
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.ORIG x3000
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LD R0, NUM
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LD R1, DEN
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JSR GCD
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ADD R4, R1, #0
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ADD R1, R2, #0
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JSR DIVIDE
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ST R2, NUM
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ADD R0, R4, #0
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JSR DIVIDE
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ST R2, DEN
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HALT
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; you can try other values for NUM and DEN by replacing these values in the simulator
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NUM .FILL #81 ; you can try other values for NUM and DEN by replacing
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DEN .FILL #24
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; Divide R0 by R1, putting quotient in R2 and remainder in R3
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DIVIDE AND R2, R2, #0 ;clean R2
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NOT R3, R1 ;store NOT of r1 in R3
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ADD R3, R3, #1 ;add one to make R3 the negative of R1
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ADD R5, R0, #0 ;store num in working variable
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DIVLOOP ADD R2, R2, #1 ;first increment of quotient counter
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ADD R5, R5, R3 ;store working number in R4, subtracting the denominator from the numerator
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BRz DIVFIN
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BRn DIVREM
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BRp DIVLOOP
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DIVREM ADD R3, R5, R1
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ADD R2, R2, #-1
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AND R5, R5, #0 ; clean r4
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RET
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DIVFIN AND R3, R3, #0 ;remainder is zero
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AND R5, R5, #0 ; clean r4
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RET
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; Euclid's algorithm for GCD of R0 and R1, result in R2
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GCD ADD R6, R7, #0 ;make call stack work (store the ret value of the original call)
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GCDLOOP JSR DIVIDE
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ADD R0, R1, #0 ; R0 = R1
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ADD R1, R3, #0 ; R1 = R3
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BRp GCDLOOP
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ADD R2, R0, #0 ;result in R2
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ADD R7, R6, #0 ;make call stack work (load the original ret value to return to original call location)
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LD R0, NUM ;load values back into r0 (bc im bad at programming)
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LD R1, DEN ;load values back into r1 (bc im bad at programming)
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RET
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.END
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