CLR #ARG = i, ART = j, AWG = r, T = c; all zeros at beginning

SET0

[ZT] #ZT = 0

$part2 TOG #First run: (ZT 0 --> 1: MDAR = ART,ARG) #Second run: (ZT --> 0: MDAR = ARG,ART)

$loop LOAD #Reads im[i,j]

MOVR

[MDDR]

INR

[ARG] #First run: i = i+1 #Second run: j = j+1

LOAD

ADD

[MDDR] #AC = AC + MDDR (F:sum = im[i,j] + im[i+1,j])

INR

[AC] #Add one to sum, to prevent floor error when div by 2

DIV2

MVAC

[MDDR] #Move the result, ready to be written

STOR #First run: (ZT 0 --> 1: MDAR = AWT,AWG) #Second run: (ZT --> 0: MDAR = AWG,AWT)

INR

[ARG]

INR

[WRG] #r = r+1

JNRG

@loop #next pixel if i != 0;

INR

[ART] #j = j+1

CLAC

MVAC

[AWG] #r = 0

INR

[AWT] #c = c+1

JNRT

@loop #if !(j == 0): next row; else: all rows finished

CLR #all zeros at beginning

JZT

@part2 #First run: (ZT = 1; loop) Second run: (ZT = 0; continue to end)