So what I am trying to accomplish is to get the LEDs on my micro controller to flash back and forth using a loop. So far I have been able to get the LEDs to flash from right to left using this code
.equ LEDS, 0x10000010
.text
.global _start
_start: movia r2, LEDS
movi r3, 0b10000000
movi r4, 0x7FFF
slli r4, r4, 3
add r4, r4, r4
load: movi r5, 0b00000001
loop: stw r5, 0(r2)
mov r6, r0
count: addi r6, r6, 1
bne r6, r4, count
beq r5, r3, load
roli r5, r5, 1
br loop
and also flash from left to right using this code
.equ LEDS, 0x10000010
.text
.global _start
_start: movia r2, LEDS
movi r3, 0b00000001
movi r4, 0x7FFF
slli r4, r4, 3
add r4, r4, r4
load: movi r5, 0b10000000
loop: stw r5, 0(r2)
mov r6, r0
count: addi r6, r6, 1
bne r6, r4, count
beq r5, r3, load
roli r5, r5, -1
br loop
The trouble I'm having is combining the two so that it flashes left to right, and then back right to left in a loop. Do i need to make changes in the loop registers or the count?
The current code branches to load when r5 is equal to r3. Instead, it should branch to the other set of code. In other words, after moving from right to left, branch to the code that flashes the LED from left to right, and vice versa. The resulting code looks like this:
.equ LEDS, 0x10000010
.text
.global _start
_start: movia r2, LEDS
movi r4, 0x7FFF
slli r4, r4, 3
add r4, r4, r4
goleft: movi r3, 0b10000000
movi r5, 0b00000001
lloop: stw r5, 0(r2)
mov r6, r0
lcount: addi r6, r6, 1
bne r6, r4, lcount
beq r5, r3, goright
roli r5, r5, 1
br lloop
goright: movi r3, 0b00000001
movi r5, 0b10000000
rloop: stw r5, 0(r2)
mov r6, r0
rcount: addi r6, r6, 1
bne r6, r4, rcount
beq r5, r3, goleft
roli r5, r5, -1
br rloop