QMK Swap Hands lighting

/*  https://www.reddit.com/r/olkb/comments/poc34h/how_can_i_convert_an_led_index_to_the_index_of/
 *  Code to change layer coloring based on if swap_hands is active or not.
 */

extern bool swap_hands;  //gives access to the variable where swap_hands is updated

void set_layer_color(int layer) {
    keypos_t key_pos;

    for (r=0; r<MATRIX_ROWS; r++) {
        for (c=0; c<MATRIX_COLS; c++) {
            if (swap_hands)
                key_pos = hand_swap_config[r][c];
            else
                key_pos = (keypos_t){.row = r, .col = c};

            uint8_t led_index = g_led_config.matrix_co[key_pos.row][key_pos.col];
            if (led_index == NO_LED)
                continue;

            HSV hsv = {
                .h = pgm_read_byte(&ledmap[layer][led_index][0]),
                .s = pgm_read_byte(&ledmap[layer][led_index][1]),
                .v = pgm_read_byte(&ledmap[layer][led_index][2]),
            };
            if (!hsv.h && !hsv.s && !hsv.v) {
                rgb_matrix_set_color(led_index, 0, 0, 0);
            } else {
                RGB   rgb = hsv_to_rgb(hsv);
                float f   = (float)rgb_matrix_config.hsv.v / UINT8_MAX;
                rgb_matrix_set_color(led_index, f * rgb.r, f * rgb.g, f * rgb.b);
            }
        }
    }
}