ceda2vga/src/vga.pio

.program vga_free_run

entrypoint_vga_free_run:
    pull
    mov y, osr
loope:
    mov x, y
    wait irq 7
loop:
    out pins, 1 [3]
    jmp x-- loop
    jmp loope

.program vga_hsync

entrypoint_vga_hsync:
    pull
    mov isr, osr
    pull

loop:
    irq set 0 [1]

    mov x, isr
    set pins, 0
hsync_pulse:
    jmp x-- hsync_pulse

    irq set 7
    mov x, osr
    set pins, 1
hsync_idle:
    jmp x-- hsync_idle
    jmp loop


.program vga_vsync

entrypoint_vga_vsync:
    pull
    mov isr, osr
    pull

loop:

    mov x, isr
vsync_pulse:
    wait irq 0
    set pins, 0
    jmp x-- vsync_pulse

    mov x, osr
vsync_idle:
    wait irq 0
    set pins, 1
    jmp x-- vsync_idle

    irq set 1

    jmp loop