TRIANGLE

; TRIANGLE reference: r0 is the level, r1 is the direction flag (1 = up, 0 = down).
; Climb 0..64, flip, fall 64..0, flip, repeat. cmp/jz turns the wave around.
      mov  r1, 1         ; start climbing
loop:
      out  p0, r0        ; draw the current level
      slp  1             ; one tick per level
      cmp  r1, 0
      jz   down          ; direction is down
      inc  r0            ; climbing
      cmp  r0, 64
      jnz  loop          ; not at the top yet
      mov  r1, 0         ; hit the top: flip to down
      jmp  loop
down:
      dec  r0            ; falling
      cmp  r0, 0
      jnz  loop          ; not at the bottom yet
      mov  r1, 1         ; hit the bottom: flip to up
      jmp  loop

# TRIANGLE. ACT 1, analog. Turn around with a direction flag and cmp/jz (CRACK's
# compare-and-branch in a visual context). The wave climbs 0..64 then falls 64..0,
# period 128. Reference is sc_a1_04_triangle.asm.
# TITLE TRIANGLE
# OBJECTIVE Ramp up 0..64 then fall 64..0, period 128.
ID sc_a1_04_triangle
WINDOW 256
DIR p0 OUT
PERIPH DAC data=p0 label=DAC_on_p0
CHAN p0 ANALOG label=CH1_p0_DAC
PAR power=1921 lines=17 chips=1