;
; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
;
; SPDX-License-Identifier: BSD-3-Clause
;

.program ws2811pio
.side_set 1

.define public T1 2
.define public T2 5
.define public T3 3

.lang_opt python sideset_init = pico.PIO.OUT_HIGH
.lang_opt python out_init     = pico.PIO.OUT_HIGH
.lang_opt python out_shiftdir = 1

.wrap_target
bitloop:
	; Side-set still takes place when instruction stalls
    out x, 1       side 0 [T3 - 1]
	; Branch on the bit we shifted out. Positive pulse
    jmp !x do_zero side 1 [T1 - 1]
do_one:
	; Continue driving high, for a long pulse
    jmp  bitloop   side 1 [T2 - 1]
do_zero:
	; Or drive low, for a short pulse
    nop            side 0 [T2 - 1]
.wrap

% c-sdk {
#include "hardware/clocks.h"
#include "ws2811pio.h"

uint ws2811pio_add( PIO pio )
{
    return pio_add_program( pio, &ws2811pio_program );
}

void ws2811pio_init( PIO pio, uint sm, uint offset, uint pin, float freq, bool rgbw )
{

    pio_gpio_init( pio, pin );
    pio_sm_set_consecutive_pindirs( pio, sm, pin, 1, true );

    pio_sm_config c = ws2811pio_program_get_default_config( offset );
    sm_config_set_sideset_pins( &c, pin );
    sm_config_set_out_shift( &c, false, true, rgbw ? 32 : 24 );
    sm_config_set_fifo_join( &c, PIO_FIFO_JOIN_TX );

    int cycles_per_bit = ws2811pio_T1 + ws2811pio_T2 + ws2811pio_T3;
    float div = clock_get_hz(clk_sys) / (freq * cycles_per_bit);
    sm_config_set_clkdiv( &c, div );

    pio_sm_init( pio, sm, offset, &c );
    pio_sm_set_enabled( pio, sm, true );
}

void ws2811pio_add_and_init( PIO pio, uint sm, uint pin, float freq, bool rgbw )
{
	uint offset = ws2811pio_add( pio );
	ws2811pio_init( pio, sm, offset, pin, freq, rgbw );
}

%}