#include "button.h"

#define DEBOUNCE_HIGH_THRES (200) // 0-255
#define DEBOUNCE_LOW_THRES  (55)  // 0-255
#define LONGPRESS_THRES     (25)  // Hz
#define BUTTON_SCAN_FREQ    (50)  // Hz

static volatile void (*onePressHandler[KEY_INDEX])(void) = { NULL };
static volatile void (*longPressHandler[KEY_INDEX])(void) = { NULL };

void btn_init()
{
	GPIOA_ModeCfg(KEY1_PIN, GPIO_ModeIN_PD);
	GPIOB_ModeCfg(KEY2_PIN, GPIO_ModeIN_PU);

	TMR3_TimerInit(FREQ_SYS/BUTTON_SCAN_FREQ);
	TMR3_ITCfg(ENABLE, TMR0_3_IT_CYC_END);
	PFIC_EnableIRQ(TMR3_IRQn);
}

void btn_onOnePress(int key, void (*handler)(void))
{
	if (key >= KEY_INDEX) return;
	onePressHandler[key] = handler;
}

void btn_onLongPress(int key, void (*handler)(void))
{
	if (key >= KEY_INDEX) return;
	longPressHandler[key] = handler;
}

__HIGH_CODE
static int debounce(int key, int is_press)
{
	static int y[KEY_INDEX], flag[KEY_INDEX];
	if (key >= KEY_INDEX) return 0;
	
	// RC filter
	y[key] -=  y[key] >> 2;
	y[key] += is_press ? 0x3F : 0;

	// Schmitt trigger
	if ((y[key] > DEBOUNCE_HIGH_THRES) && (flag[key] == 0))
		flag[key] = 1;
	if ((y[key] < DEBOUNCE_LOW_THRES) && (flag[key] == 1))
		flag[key] = 0;

	return flag[key];
}

__HIGH_CODE
static void check(int k)
{
	static int hold[KEY_INDEX], is_longpress[KEY_INDEX];
	if (k >= KEY_INDEX) return; // TODO: assert instead

	if (debounce(k, isPressed(k))) {
		hold[k]++;
		if (hold[k] >= LONGPRESS_THRES && is_longpress[k] == 0) {
			is_longpress[k] = 1;
			if (longPressHandler[k]) longPressHandler[k]();
		}
	} else {
		if (hold[k] > 0 && hold[k] < LONGPRESS_THRES) {
			if (onePressHandler[k]) onePressHandler[k]();
		}
		is_longpress[k] = 0;
		hold[k] = 0;
	}
}

__HIGH_CODE
static void check_keys()
{
	for (int k=0; k<KEY_INDEX; k++) {
		check(k);
	}
}

__INTERRUPT
__HIGH_CODE
void TMR3_IRQHandler(void)
{
	if (TMR3_GetITFlag(TMR0_3_IT_CYC_END)) {		
		check_keys();
		TMR3_ClearITFlag(TMR0_3_IT_CYC_END);
	}
}