8051 Program – bubble sort ascending order

;sort an array using the Bubble Sort algorithm in ascending order.
;compare adjacent elements and sort with respect to each other.
;number of passes is one less than the number of elements in the array
;and number of iterations in each pass is the
;total number of elements minus the current pass number.
	ORG 0H
	ARRAY_ADDR EQU 4000H
	NO_ELEMENTS EQU 08H
MAIN:
	MOV DPTR, #ARRAY_ADDR
	MOV A, #02H
	MOVX @DPTR, A
	INC DPTR
	MOV A, #13H
	MOVX @DPTR, A
	INC DPTR
	MOV A, #0A4H
	MOVX @DPTR, A
	INC DPTR
	MOV A, #24H
	MOVX @DPTR, A
	INC DPTR
	MOV A, #76H
	MOVX @DPTR, A
	INC DPTR
	MOV A, #43H
	MOVX @DPTR, A
	INC DPTR
	MOV A, #0BCH
	MOVX @DPTR, A
	INC DPTR
	MOV A, #37H
	MOVX @DPTR, A
	LCALL SORT
	SJMP MAIN
SORT:
	MOV R0, #NO_ELEMENTS	;Counter for LOOP1
loop1:		;Outer Loop - Handles number of passes
	MOV DPTR, #ARRAY_ADDR	;Point to beginning of array
	MOV A, R0	;Initialize R1 - the counter for LOOP2
	MOV R1, A	;to the value of R0 - the number of iterations in each pass is same
		;as the number of elements minus serial number of the current pass.
loop2:		;Inner Loop - Handles each pass.
	MOVX A, @DPTR	;Copy a number of the array to the accumulator
	MOV R2, A	;and store it in R2.
	INC DPTR	;Move to the net number
	MOVX A, @DPTR	;and store that in the accumulator.
	SUBB A, R2	;Subtract the first from the second.
	JNC iteration	;If no carry is generated the second is greater and the numbers are
		;in order with respect to each other. Otherwise they must be swapped.
swapnumbers:
	MOVX A, @DPTR	;Move the second number to the accumulator.
	XCH A, R2	;Exchange contents of the accumulator and R2. This makes A contain
		;the first number and R2 the second.
	MOVX @DPTR, A	;Store the first number at the place where the second one was stored.
	DEC DPL	;Move to the previous memory location.
	MOV A, R2	;Copy the second number to the accumulator
	MOVX @DPTR, A	;and store it in the first number's place.
	INC DPTR	;Move to the next memory location.
iteration:	DJNZ R1, loop2	;Move on to the next iteration of the current pass.
pass:	DJNZ R0, loop1	;Move on to the next pass.
	RET
	END

; bubble sort
; external memory
	ORG 0H
START :
	MOV R1,#10H	;Outer loop count
OUTLOOP:	MOV R0,#10H	;Inner loop count
	MOV DPTR,#9000H
INLOOP:	CLR C	;Carry=0
	MOVX A,@DPTR
	MOV R2,A	;R2=first no
	INC DPTR
	MOVX A,@DPTR	;Acc=second no
	MOV R3,A
	SUBB A,R3	;Compare
	JNC SKIP
	XCH A,R2	;Exchange
SKIP:	MOVX @DPTR,A	;Big no -> mem
	DEC 82H	;DPL=DPL-1
	MOV A,R2
	MOVX @DPTR,A	;Small no -> mem
	INC DPTR
	DEC R0
	CJNE R0,#01H,INLOOP
	DEC R1
	CJNE R1,#01H,OUTLOOP
	SJMP $
	END

; bubble sort ascending order
; external memory
	ORG 0H
	MOV R0,#05
L1:	MOV DPTR,#9000H
	MOV A,R0
	MOV R1,A
L2:	MOVX A,@DPTR
	MOV B,A
	INC DPTR
	MOVX A,@DPTR
	CLR C
	MOV R2,A
	SUBB A,B
	JNC NOEXCHG
	MOV A,B
	MOVX @DPTR,A
	DEC DPL
	MOV A,R2
	MOVX @DPTR,A
	INC DPTR
NOEXCHG:	DJNZ R1,L2
	DJNZ R0,L1
	SJMP $
	ORG 9000H
	DB 2,5,1,9,7,6
	END
; Result: 9000:01, 02, 05,06,07,09

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