test.s

;**********************************************************************************************
; Author:  Maxwell Chehab
; Pre Lab 1: Data Conversions and Signed Numbers                  
; Date Created: September 20, 2018             
; Last Modified:                                                                 
; Description: this program will compute Convert A BCD number to xten and xunit place. Convert
;			   them into a binary number and perform a simple calculation
; Inputs: none
; Outputs: view the specified locations (0x20000000 to 0x20000005)
;**********************************************************************************************
	
	THUMB
	AREA   	MyData, DATA, READWRITE, ALIGN=2
X			RN		R5
N			RN		R7


	AREA MyCode, CODE, READONLY, ALIGN=2
	EXPORT __main


__main
	BL		BCD_to_bin			; Go to ConvertBCDToBIN
	BL		Absolute_value			; Go to ConvertBCDToBIN
	MOV		R0, #0xFF
	
	
Absolute_value
	PUSH	{ LR, R1 }
	;MOV	N,		#0xFFFFFFBB		; Assign -69 to N

	MOV		N,		#0x00000045		; Assign 69 to N
	MOV		R1,		N
	CMP		R1,		#0
	BGE		positive
	BL		negative
	POP		{ LR, R1 }
	BX		LR
positive
	MOV		R8,		N
	BX		LR
negative
	NEG		R8,		R1
	BX		LR

BCD_to_bin 
	PUSH 	{ R1 - R3 }
	MOV 	X,		#0x26			; Store x as decided value (0x26)
	MOV		R1,		X				; Store BCD X number in R1
	MOV		R2,		R1				; Store BCD X number in R2
	AND 	R1,		#0x0000000F		; R1 has the units digits
	LSR		R2, 	#4				; R2 has the tens digit
	MOV 	R3, 	R2				; R3 gets a copy of R2
	LSL		R2,		#1				; R2 gets 2*Xten
	ADD		R2,		R3, 	LSL #3	; R2 gets 2 * Xten + 8 * Xten = 10Xten
	ADD		R2,		R1				; R2 gets 10 * Xten + Xunit
	MOV		R6,		R2				; R5 now has the binary number
	POP		{ R1 - R3 }
	BX		LR
	

	
	;LDR 	R0, 	=Xten 			; find the location of Xten 
	;LDR 	R0, 	=Xunit			; find the location of Xunit
	;LDR 	R0, 	=Xten_ascii 	; find the location of Xten_ascii 
	;LDR 	R0, 	=Xunit_ascii	; find the location of Xunit_ascii
	;LDR 	R0, 	=Xbin			; find the location of Xbin
	;LDR 	R0, 	=Ybin			; find the location of Ybin


	; Step 1 Split BCD Number
	;MOV 	R1, 	X				; R1 gets a copy of X
	;MOV		R2, 	R1				; R2 gets a copy of X
	;AND 	R1,		X, #0x0000000F 	; Xunit has the units digit 
	;LDR 	R0,		=Xunit			; R0 <- address of Xunit
	;STRB	R1, 	[R0]			; Store R1 in Xunit
	;LSR 	R2, 	#4				; R2 has the tens digit
	;LDR		R0,		=Xten			; R0 <- address of Xten
	;STRB	R2,		[R0]			; Store R2 in Xten
	
	; Step 2 Convert to Ascii
	;LDR		R0,		=Xunit			; Store Xunit address in R0
	;LDR		R1,		[R0]			; Store value at R0 into R1
	;ADD		R1,		#48				; Add 48 to R1
	;LDR 	R0,		=Xunit_ascii	; R0 <- address of Xunit_ascii7
	;STRB	R1, 	[R0]			; Store R1 in Xunit_ascii
	;LDR		R0,		=Xten			; Store Xten address in R0
	;LDR		R1,		[R0]			; Store value at R0 into R1
	;ADD		R1,		#48				; Add 48 to R1
	;LDR 	R0,		=Xten_ascii		; R0 <- address of Xten_ascii
	;STRB	R1, 	[R0]			; Store R1 in Xten_ascii
	
	; Step 3 Convert to single binary number
	;MOV 	X,		#0x26			; Store x as decided value (0x26)
	;MOV		R1,		X				; Store BCD X number in R1
	;MOV		R2,		R1				; Store BCD X number in R2
	;AND 	R1,		#0x0000000F		; R1 has the units digits
	;LSR		R2, 	#4				; R2 has the tens digit
	;MOV 	R3, 	R2				; R3 gets a copy of R2
	;LSL		R2,		#1				; R2 gets 2*Xten
	;ADD		R2,		R3, 	LSL #3	; R2 gets 2 * Xten + 8 * Xten = 10Xten
	;ADD		R2,		R1				; R2 gets 10 * Xten + Xunit
	;LDR 	R0,		=Xbin			; R0 <- address of Xbin
	;STRB	R2,		[R0]			; Store R2 in Xbin
	
	; Step 4 Ybin = 50 - 3 * Xbin
	;MOV		R5,		R2				; Store value at R2 into R5 
	;MOV 	R1,		R5				; Make a copy of Xbin in R1
	;LSL		R5,		R5, 	#1		; Xbin * 2
	;ADD 	R5,		R5,		R1		; Xbin * 2 + Xbin
	
	;MOV 	R2,		#50				; R2 = 50
	;SUB		R2,		R5				; 50 - R5
	;LDR		R0,		=Ybin			; R0 <- address of Ybin
	;STRB	R2,		[R0]			; Store R2 in Ybin
	;LSL  	R5, 	R5, #3 	; R5= 8*R5=8*Vx
	;SUB  	R5, 	R5, Vx 	; R5= R5-Vx=8*Vx=7*Vx
	;ADD	 	R5, 	R5, #120 ; R5= R5+120=(7*Vx)+120
	;LDR  	R0, 	=Vy 	; R0= address of Vy
	;STR  	R5, 	[R0] 	; Vy= R5
	
	; Vz = Vy / 8 + 25
	;LSR 	R5, 	R5, #3 	; R5= 8/R5=8/Vy
	;ADD 	R5, 	R5, #25	; R5 = R5/8+25
	;LDR  	R0, 	=Vz 	; R0= address of Vz
	;STR  	R5, 	[R0] 	; Vz= R5
	
	END