Actually minimal version of rp2040 scanvideo

scanvideo_minimal.c

/*
 * Actually minimal scanvideo example
 */

#include <stdio.h>

#include "pico.h"
#include "pico/scanvideo.h"
#include "pico/scanvideo/composable_scanline.h"
#include "pico/stdlib.h"

// Highest possible VGA_MODE with RAW_RUN seems to be 320x240_60
#define VGA_MODE vga_mode_320x240_60

extern const struct scanvideo_pio_program video_24mhz_composable;

#define ALIGNED_SCANLINE_WORDS 0

static void render_scanline(struct scanvideo_scanline_buffer *dest) {
    uint32_t *buf = dest->data;
    uint16_t *output = (uint16_t*)buf;
    int l = scanvideo_scanline_number(dest->scanline_id);

    *output++ = COMPOSABLE_RAW_RUN;
    // First color byte in RAW_RUN comes before run length
    *output++ = l & 2 ? 0xffff : 0x0000;
    *output++ = VGA_MODE.width;
    *output++ = l & 2 ? 0x0000 : 0xffff;

    for (int i = 2; i < VGA_MODE.width; i+=2) {
        *output++ = l & 2 ? 0xffff : 0x0000;
        *output++ = l & 2 ? 0x0000 : 0xffff;
    }

    // Must end with black pixel
    *output++ = COMPOSABLE_RAW_1P;
    *output++ = 0;

    if (ALIGNED_SCANLINE_WORDS) {
        *output++ = COMPOSABLE_EOL_ALIGN;
    } else {
        *output++ = COMPOSABLE_EOL_SKIP_ALIGN;
        *output++ = 0xffff;
    }

    dest->data_used = (uint16_t)(((uint32_t*)output) - buf);
    dest->status = SCANLINE_OK;
}

// static void frame_update_logic() {}

int vga_main(void) {
    scanvideo_setup(&VGA_MODE);
    scanvideo_timing_enable(true);

    while (true) {
        struct scanvideo_scanline_buffer *scanline_buffer = scanvideo_begin_scanline_generation(true);
        // frame_update_logic();
        render_scanline(scanline_buffer);
        scanvideo_end_scanline_generation(scanline_buffer);
    }

    return 0;
}

int main(void) {
    setup_default_uart();
    return vga_main();
}