/**
 * @file sweep.c
 * @brief Periodic staircase sweep state machine.
 */

#include "sweep.h"

#include <stddef.h>

bool sweep_start(sweep_t *sweep, const sweep_config_t *config, uint32_t tick_us)
{
    if ((sweep == NULL) || (config == NULL) || (tick_us == 0u) ||
        (config->min_code > config->max_code) || (config->step_code == 0u) ||
        (config->step_period_us < tick_us))
    {
        return false;
    }

    sweep->min_code = config->min_code;
    sweep->max_code = config->max_code;
    sweep->step_code = config->step_code;
    sweep->step_ticks = config->step_period_us / tick_us;
    sweep->pause_ticks = ((uint32_t)config->pause_ms * 1000u) / tick_us;
    sweep->next_code = config->min_code;
    sweep->countdown_ticks = 1u;
    sweep->enabled = 1u;
    return true;
}

void sweep_stop(sweep_t *sweep)
{
    if (sweep != NULL)
    {
        sweep->enabled = 0u;
    }
}

bool sweep_tick(sweep_t *sweep, uint16_t *out_code)
{
    if ((sweep->enabled == 0u) || (--sweep->countdown_ticks != 0u))
    {
        return false;
    }

    *out_code = (uint16_t)sweep->next_code;
    sweep->countdown_ticks = sweep->step_ticks;
    if (sweep->next_code == sweep->min_code)
    {
        /* The lower bound is held for the inter-sweep pause. */
        sweep->countdown_ticks += sweep->pause_ticks;
    }

    if (sweep->next_code >= sweep->max_code)
    {
        sweep->next_code = sweep->min_code;
    }
    else
    {
        sweep->next_code += sweep->step_code;
        if (sweep->next_code > sweep->max_code)
        {
            sweep->next_code = sweep->max_code;
        }
    }
    return true;
}