blinky-esp/main/patterns/random.cpp

static const char *TAG = "random";
#include <esp_log.h>

#include <esp_random.h>

#include "presets.hpp"
#include "utils.hpp"


static Color rand_color() {
    static const Color colors[] = {
        {255,   0,   0},
        { 78,  25,   0},
        {255, 160,   0},
        {  0, 255,   0},
        {  0,   0, 255},
        { 38,  10,  42},
    };
    return colors[esp_random() % 6];
}

class RandomPattern : public Pattern {
private:
    struct State : Pattern::State {
        State(int _len, int gap) :
                    last_us(0), step(0), offset(0),
                    n_colors((_len + gap) / (gap + 1)), colors(new Color[n_colors])
                {
            for (Color *color = colors, *end = colors + n_colors; color < end; ++color) {
                *color = rand_color();
            }
        }
        ~State() { delete[] colors; }

        int64_t last_us;
        int step;
        int offset;
        int n_colors;
        Color *colors;
    };

public:
    RandomPattern(int _delay_ms, int _gap) : delay_us(_delay_ms * 1000), gap(_gap) {}

    State* start(int len) const { return new State(len, gap); }

    void step(Color colors[], int len, Pattern::State *_state) const {
        State *state = (State*)_state;

        int64_t now_us = time_us();
        int64_t elapsed_us = now_us - state->last_us;
        bool should_step = (state->last_us == 0) || (elapsed_us >= delay_us && delay_us > 0);
        if (should_step) {
            state->last_us = (elapsed_us >= delay_us + 100000 ? now_us : state->last_us + delay_us);

            int step = state->step;
            int offset = state->offset;
            Color *inc = state->colors + offset;
            Color *outc = colors;

            if ((gap + 1 - step) % (gap + 1) == 0) *inc = rand_color();

            for (int i = 0; i < len; i++) {
                if ((i - step + gap + 1) % (gap + 1) == 0) {
                    *outc = *inc--;
                    if (inc < state->colors) inc += state->n_colors;
                } else {
                    *outc = {0, 0, 0};
                }
                ++outc;
            }

            step++;
            if (step > gap) {
                step -= gap + 1;
                ++offset;
                if (offset >= state->n_colors) offset -= state->n_colors;
                state->offset = offset;
            }
            state->step = step;
        }
    }

private:
    int delay_us;
    int gap;
};


Pattern* json_random_pattern(cJSON *pattern, const Presets::ColorMap &colors) {
    int delay_ms = 500;
    int gap = 1;

    if (pattern->type != cJSON_Object) {
        ESP_LOGE(TAG, "Not an object: %s", pattern->string);
        return NULL;
    }

    cJSON *jdelay = cJSON_GetObjectItem(pattern, "delay");
    if (jdelay) {
        if (jdelay->type != cJSON_Number) {
            ESP_LOGE(TAG, "Not a number: %s", jdelay->string);
        } else {
            delay_ms = jdelay->valuedouble * 1000.;
        }
    }

    cJSON *jgap = cJSON_GetObjectItem(pattern, "gap");
    if (jgap) {
        if (jgap->type != cJSON_Number) {
            ESP_LOGE(TAG, "Not a number: %s", jgap->string);
        } else {
            gap = jgap->valueint;
        }
    }

    return new RandomPattern(delay_ms, gap);
}