Code Examples from Class - Revision history

Frohro at 18:58, 7 November 2014

2014-11-07T18:58:55Z

← Older revision		Revision as of 11:58, 7 November 2014
Line 254:		Line 254:
	add r4, r4, r6 ; r4=r5+r6		add r4, r4, r6 ; r4=r5+r6
	subs r4, r4, #10 ; Subtract 10 (base 10) to see if there is a carry.		subs r4, r4, #10 ; Subtract 10 (base 10) to see if there is a carry.
	~~bmi no_carry~~		bpl carry
	~~mov r7, #1 ; set the~~ carry
	~~b roll_to_next_digit~~
	~~no_carry~~
	mov r7, #0 ; set carry to zero		mov r7, #0 ; set carry to zero
	add r4, r4, #10 ; Add the 10 back in as there was no carry needed.		add r4, r4, #10 ; Add the 10 back in as there was no carry needed.
			b roll_to_next_digit
			carry
			mov r7, #1 ; set the carry
	roll_to_next_digit		roll_to_next_digit
	orr r3, r3, r4 ; Add these digits into the sum.		orr r3, r3, r4 ; Add these digits into the sum.

Frohro at 16:43, 7 November 2014

2014-11-07T16:43:32Z

← Older revision		Revision as of 09:43, 7 November 2014
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	; Subroutine to add two BCD numbers in 32 bit form with each nibble		; Subroutine to add two BCD numbers in 32 bit form with each nibble
	; representing a digit.		; representing a digit.
	; locals: r8 for digit counter, mask 0xf, r5 & r6 for masked addends,		; locals: r8 for digit counter, single digit mask 0xf, r5 & r6 for masked addends,
	; working BCD_carry, r7 ~~for~~		; working BCD_carry, r7
	; working result in r4		; working result in r4
	; the summed digits go in r3		; the summed digits go in r3
Line 261:		Line 261:
	add r4, r4, #10 ; Add the 10 back in as there was no carry needed.		add r4, r4, #10 ; Add the 10 back in as there was no carry needed.
	roll_to_next_digit		roll_to_next_digit
	orr r3, r3, r4 ; Add ~~thise~~ digits into the sum.		orr r3, r3, r4 ; Add these digits into the sum.
	ror r0, #4		ror r0, #4
	ror r1, #4		ror r1, #4
	ror r3, #4		ror r3, #4
	subs r8, r8, #1 ; Decrement digit counter		subs r8, r8, #1 ; Decrement the digit counter
	bne loop ; If it isn't zero do the next digit.		bne loop ; If it isn't zero do the next digit.
	mov r0, r3 ; Set the output registers. r0 is result. r1 is carry.		mov r0, r3 ; Set the output registers. r0 is result. r1 is carry.

Frohro at 01:46, 2 November 2014

2014-11-02T01:46:27Z

@@ Line 272: / Line 272: @@
 	END
 </nowiki>
 ----
 *GPIO Example

Frohro at 15:53, 27 October 2014

2014-10-27T15:53:43Z

← Older revision		Revision as of 08:53, 27 October 2014
Line 107:		Line 107:
	; saving registers on the stack, etc.		; saving registers on the stack, etc.

	; Rob Frohne, 1/3/2013		; Rob Frohne, 11/3/2013

	stack_start EQU 0x40001000		stack_start EQU 0x40001000
Line 117:		Line 117:
	ldr sp, =stack_start ; Tell where we will place the stack.		ldr sp, =stack_start ; Tell where we will place the stack.
	; (It goes down (lower addresses from here.)		; (It goes down (lower addresses from here.)
	mov r1, #1 ; Store some numebers in some registers		mov r1, #1 ; Store some numebers in some registers
	mov r2, #2		mov r2, #2
	mov r3, #3		mov r3, #3
Line 128:		Line 128:
	subroutine		subroutine
	stmfd sp!, {r1-r2,lr} ; save used registers and the link register (r14)		stmfd sp!, {r1-r2,lr} ; save used registers and the link register (r14)
	mov r1,#0xffffffff ; mess up the registers		mov r1,#0xffffffff ; mess up the registers
	mov r2, r1		mov r2, r1
	ldmfd sp!, {r1,r2,pc} ; pop the stack and return		ldmfd sp!, {r1,r2,pc} ; pop the stack and return
Line 145:		Line 145:
	ENTRY		ENTRY

	ldr r0,=end ; load the ~~beginning~~ address of the code & initialize it as the pointer.		ldr r0,=end ; load the end address of the code & initialize it as the pointer.
	ldr r2,=begin ; load the ~~ending~~ address of the code.		ldr r2,=begin ; load the beginning address of the code.
	mov r3,#0x7fffffff ; Initialize r3 as the most positive number.		mov r3,#0x7fffffff ; Initialize r3 as the most positive number.

	loop		loop
	ldr r6,[r2],#4 ; load the next data into r6 and post increment r2 for the next data.		ldr r6,[r2],#4 ; load the next data into r6 and post increment r2 for the next data.
	cmp r6,r3 ; Find out if r6 > r3. result from r6-r3 like subs r7,r6,r3 without r6 necessary.		cmp r6,r3 ; Find out if r6 > r3. result from r6-r3 like subs r7,r6,r3 without r6 necessary.
	bgt no_update ; If it is no update.		bgt no_update ; If it is no update.
	mov r3,r6 ; update if r6 is lower than r3.		mov r3,r6 ; update if r6 is lower than r3.
	no_update		no_update
	cmp r0,r2 ; are we at the end yet		cmp r0,r2 ; are we at the end yet
	bne loop ; if r7 != 0 then keep looping		bne loop ; if r7 != 0 then keep looping

	stop b stop		stop b stop

Frohro at 06:22, 24 October 2014

2014-10-24T06:22:42Z

← Older revision		Revision as of 23:22, 23 October 2014
Line 55:		Line 55:
	END		END
	</nowiki>		</nowiki>
	~~___~~		----

	* 64 Bit Add		* 64 Bit Add

Frohro at 06:21, 24 October 2014

2014-10-24T06:21:33Z

← Older revision		Revision as of 23:21, 23 October 2014
Line 27:		Line 27:

	----		----
			*Factorial 2014
			<nowiki>
			_ AREA Add, CODE
			ENTRY
			; This program takes the factorial of n (in r2)
			n EQU 0

			ldr r2,=n ; Load r2 with the number to take the factorial of.
			cmp r2,#0 ; Is n=0
			bne check_for_1
			mov r4,#1
			b stop
			check_for_1
			cmp r2,#1
			bne initialize_r4
			mov r4,#1
			b stop
			initialize_r4
			mov r4,r2
			sub r3,r4,#1
			loop
			mul r5,r4,r3
			mov r4,r5
			subs r3,r3,#1
			bne loop
			stop b stop
			END
			</nowiki>
			___

	* 64 Bit Add		* 64 Bit Add

Frohro at 23:32, 17 December 2013

2013-12-17T23:32:55Z

← Older revision		Revision as of 16:32, 17 December 2013
Line 200:		Line 200:
	; the summed digits go in r3		; the summed digits go in r3
	; inputs: r0+r1		; inputs: r0+r1
	; ~~outupts~~: r0 result and r1 carry		; outputs: r0 result and r1 carry
	; only r4-r8 are saved.		; only r4-r8 are saved.
	; Rob Frohne 11/12/13		; Rob Frohne 11/12/13

Frohro at 22:46, 17 December 2013

2013-12-17T22:46:08Z

← Older revision		Revision as of 15:46, 17 December 2013
Line 408:		Line 408:

	main		main
	~~ldr sp, = Stack_Mem ; load stack pointer~~
	ldr r1, =PINSEL0		ldr r1, =PINSEL0
	mov r0, #0 ; set P0.0 to P0.15 as GPIO		mov r0, #0 ; set P0.0 to P0.15 as GPIO

Frohro at 01:05, 13 December 2013

2013-12-13T01:05:07Z

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Frohro at 22:09, 6 December 2013

2013-12-06T22:09:08Z

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