#include <avr/io.h>
#include <util/delay.h>

#define MATRIX_X(t) t##B
#define MATRIX_Y1(t) t##C
#define MATRIX_Y2(t) t##D
#define MATRIX_Y_SPLIT 6
#define MATRIX_Y2_DELTA (-1)
#define MASK_Y1 0b00111111
#define MASK_Y2 0b11100000

#define DELAY_ROW_SWITCH() _delay_ms(1) //_delay_us(1)

#define BAUDRATE 9600

/* Keycode from include/linux/input.h */
#define KEY_RESERVED		0
#define KEY_ESC			1
#define KEY_1			2
#define KEY_2			3
#define KEY_3			4
#define KEY_4			5
#define KEY_5			6
#define KEY_6			7
#define KEY_7			8
#define KEY_8			9
#define KEY_9			10
#define KEY_0			11
#define KEY_MINUS		12
#define KEY_EQUAL		13
#define KEY_BACKSPACE		14
#define KEY_TAB			15
#define KEY_Q			16
#define KEY_W			17
#define KEY_E			18
#define KEY_R			19
#define KEY_T			20
#define KEY_Y			21
#define KEY_U			22
#define KEY_I			23
#define KEY_O			24
#define KEY_P			25
#define KEY_LEFTBRACE		26
#define KEY_RIGHTBRACE		27
#define KEY_ENTER		28
#define KEY_LEFTCTRL		29
#define KEY_A			30
#define KEY_S			31
#define KEY_D			32
#define KEY_F			33
#define KEY_G			34
#define KEY_H			35
#define KEY_J			36
#define KEY_K			37
#define KEY_L			38
#define KEY_SEMICOLON		39
#define KEY_APOSTROPHE		40
#define KEY_GRAVE		41
#define KEY_LEFTSHIFT		42
#define KEY_BACKSLASH		43
#define KEY_Z			44
#define KEY_X			45
#define KEY_C			46
#define KEY_V			47
#define KEY_B			48
#define KEY_N			49
#define KEY_M			50
#define KEY_COMMA		51
#define KEY_DOT			52
#define KEY_SLASH		53
#define KEY_RIGHTSHIFT		54
#define KEY_KPASTERISK		55
#define KEY_LEFTALT		56
#define KEY_SPACE		57
#define KEY_CAPSLOCK		58
#define KEY_F1			59
#define KEY_F2			60
#define KEY_F3			61
#define KEY_F4			62
#define KEY_F5			63
#define KEY_F6			64
#define KEY_F7			65
#define KEY_F8			66
#define KEY_F9			67
#define KEY_F10			68
#define KEY_NUMLOCK		69
#define KEY_SCROLLLOCK		70
#define KEY_KP7			71
#define KEY_KP8			72
#define KEY_KP9			73
#define KEY_KPMINUS		74
#define KEY_KP4			75
#define KEY_KP5			76
#define KEY_KP6			77
#define KEY_KPPLUS		78
#define KEY_KP1			79
#define KEY_KP2			80
#define KEY_KP3			81
#define KEY_KP0			82
#define KEY_KPDOT		83

#define KEY_ZENKAKUHANKAKU	85
#define KEY_102ND		86
#define KEY_F11			87
#define KEY_F12			88
#define KEY_RO			89
#define KEY_KATAKANA		90
#define KEY_HIRAGANA		91
#define KEY_HENKAN		92
#define KEY_KATAKANAHIRAGANA	93
#define KEY_MUHENKAN		94
#define KEY_KPJPCOMMA		95
#define KEY_KPENTER		96
#define KEY_RIGHTCTRL		97
#define KEY_KPSLASH		98
#define KEY_SYSRQ		99
#define KEY_RIGHTALT		100
#define KEY_LINEFEED		101
#define KEY_HOME		102
#define KEY_UP			103
#define KEY_PAGEUP		104
#define KEY_LEFT		105
#define KEY_RIGHT		106
#define KEY_END			107
#define KEY_DOWN		108
#define KEY_PAGEDOWN		109
#define KEY_INSERT		110
#define KEY_DELETE		111
#define KEY_MACRO		112
#define KEY_MUTE		113
#define KEY_VOLUMEDOWN		114
#define KEY_VOLUMEUP		115
#define KEY_POWER		116	/* SC System Power Down */
#define KEY_KPEQUAL		117
#define KEY_KPPLUSMINUS		118
#define KEY_PAUSE		119
#define KEY_SCALE		120	/* AL Compiz Scale (Expose) */

#define KEY_KPCOMMA		121
#define KEY_HANGEUL		122
#define KEY_HANGUEL		KEY_HANGEUL
#define KEY_HANJA		123
#define KEY_YEN			124
#define KEY_LEFTMETA		125
#define KEY_RIGHTMETA		126
#define KEY_COMPOSE		127

#define SKEY_FN 255
// #define KEYCODE_FN 127

/*
 * Special keys:
 *   * Control : Code
 *   * Alt     : Del
 *   * FN      : Delword
 *   * Del     : Inhalt
 *   * `       : SM
 *   * Escape  : Storno
 *   * Print   : Menu
 *   * Pause   : GS End
 *
 * FN Keymap:
 *   * F-Keys                   : Number keys for F1-F10, and ? and ` for F11-F12
 *   * Home / End / PGUP / PGDN : Arrow keys
 *   * Sys rq                   : Print
 */
static uint8_t keycode_translation_matrix[2][9][8] = {
	{ /* Standard keymap */
	  {KEY_5, KEY_6, KEY_R, KEY_T, KEY_C, KEY_F, KEY_UP, 0},
	  {KEY_8, KEY_7, KEY_Y, KEY_H, KEY_G, KEY_V, KEY_PAUSE, 0},
	  {KEY_1, KEY_2, KEY_Q, KEY_Z, KEY_A, KEY_S, KEY_CAPSLOCK, 0},
	  {KEY_9, KEY_J, KEY_I, KEY_U, KEY_B, KEY_N, KEY_RIGHT, 0},
	  {KEY_MINUS, KEY_0, KEY_P, KEY_O, KEY_M, KEY_COMMA, KEY_SYSRQ, 0},
	  {KEY_DELETE, KEY_SEMICOLON, KEY_RIGHTBRACE, KEY_LEFTBRACE, KEY_LEFT, KEY_DOWN, 0, KEY_LEFTCTRL},
	  {KEY_4, KEY_3, KEY_W, KEY_E, KEY_D, KEY_X, KEY_TAB, 0},
	  {KEY_GRAVE, KEY_ESC, KEY_ENTER, KEY_BACKSPACE, KEY_LEFTALT, SKEY_FN, KEY_LEFTSHIFT, KEY_SPACE},
	  {KEY_EQUAL, KEY_L, KEY_BACKSLASH, KEY_K, KEY_DOT, KEY_SLASH, 0, KEY_APOSTROPHE}
	},
	{ /* FN keymap */
	  {KEY_F5, KEY_F6, KEY_R, KEY_T, KEY_C, KEY_F, KEY_PAGEUP, 0},
	  {KEY_F8, KEY_F7, KEY_Z, KEY_H, KEY_G, KEY_V, KEY_PAUSE, 0},
	  {KEY_F1, KEY_F2, KEY_Q, KEY_102ND, KEY_A, KEY_S, KEY_CAPSLOCK, 0},
	  {KEY_F9, KEY_J, KEY_I, KEY_U, KEY_B, KEY_N, KEY_END, 0},
	  {KEY_F11, KEY_F10, KEY_P, KEY_O, KEY_M, KEY_COMMA, KEY_SYSRQ, 0},
	  {KEY_DELETE, KEY_SEMICOLON, KEY_RIGHTBRACE, KEY_LEFTBRACE, KEY_HOME, KEY_PAGEDOWN, 0, KEY_LEFTCTRL},
	  {KEY_F4, KEY_F3, KEY_W, KEY_E, KEY_D, KEY_X, KEY_TAB, 0},
	  {KEY_GRAVE, KEY_ESC, KEY_ENTER, KEY_BACKSPACE, KEY_LEFTALT, SKEY_FN, KEY_LEFTSHIFT, KEY_SPACE},
	  {KEY_F12, KEY_L, KEY_BACKSLASH, KEY_K, KEY_DOT, KEY_SLASH, 0, KEY_APOSTROPHE}
	}
};

uint8_t matrix_state_last_vector[9] = {0xFF, 0xFF, 0xFF, 0xFF,
				       0xFF, 0xFF, 0xFF, 0xFF,
				       0xFF};


uint8_t fn_active = 0;

void uart_putc(char c)
{
	while (!(UCSRA & (1 << UDRE)));
	UDR = c;
}

void process_key_event(uint8_t col, uint8_t row, uint8_t state)
{
	char c;
	uint8_t keycode;
	int event = 0;

	keycode = keycode_translation_matrix[fn_active][col][row];

	if (keycode == SKEY_FN) {
		fn_active = state;
#ifdef KEYCODE_FN
		c = KEYCODE_FN | (state << 7);
		event = 1;
#endif
	} else {
		c = keycode | (state << 7);
		event = 1;
	}

	if (event) {
		uart_putc(0xFF);
		uart_putc(0x55);
		uart_putc(c);
	}
}

void matrix_scan_col(uint8_t col)
{
	uint8_t matrix_state;
	uint8_t row;
	uint8_t bit;

	if (col < MATRIX_Y_SPLIT) {
		MATRIX_Y2(DDR) &= ~(MASK_Y2);
		MATRIX_Y1(DDR) = (MATRIX_Y1(DDR) & ~(MASK_Y1)) |
				(1 << col);
	} else {
		MATRIX_Y2(DDR) = (MATRIX_Y2(DDR) & ~(MASK_Y2)) |
				(1 << (col + MATRIX_Y2_DELTA));
		MATRIX_Y1(DDR) &= ~(MASK_Y1);
	}

	DELAY_ROW_SWITCH();

	matrix_state = MATRIX_X(PIN);

	for (row = 0; row < 8; ++row) {
		bit = (1 << row);
		if ((matrix_state ^ matrix_state_last_vector[col]) & bit) {
			process_key_event(col, row, !(matrix_state & bit));
		}
	}

	matrix_state_last_vector[col] = matrix_state;
}

int main()
{
	int col;

	/* Config I/O */
	MATRIX_X(DDR) = 0; /* Columns as input */
	MATRIX_X(PORT) = 0xFF; /* Enable pull-ups for columns */
	MATRIX_Y1(DDR) &= ~MASK_Y1; /* Disable rows */
	MATRIX_Y2(DDR) &= ~MASK_Y2; /* Disable rows */
	MATRIX_Y1(PORT) &= ~MASK_Y1; /* Pull row low when selected */
	MATRIX_Y2(PORT) &= ~MASK_Y2; /* Pull row low when selected */
	UCSRB = (1 << TXEN);
	UBRRH = ((((F_CPU / BAUDRATE) / 16) - 1) >> 8);
	UBRRL = (((F_CPU / BAUDRATE) / 16) - 1);

	fn_active = 0;

	/* Continuously scan matrix */
	while (1) {
		for (col = 0; col < 9; ++col) {
			matrix_scan_col(col);
		}
	}
}