/*
Copyright 2017 Balz Guenat
based on work by Jun Wako <wakojun@gmail.com>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
 * scan matrix
 */
#include <stdint.h>
#include <stdbool.h>
#include "wait.h"
#include "print.h"
#include "debug.h"
#include "util.h"
#include "timer.h"
#include "matrix.h"
#include "led.h"
#include "avr/timer_avr.h"

// Timer resolution check
#if (1000000/TIMER_RAW_FREQ > 20)
#   error "Timer resolution(>20us) is not enough for HHKB matrix scan tweak on V-USB."
#endif


/*
 * Pin configuration for ATMega32U4
 *
 * Row:     PD4-6, 7(~EN)
 * Col:     PB0-2, 3(Z5 ~EN), 4(Z4 ~EN)
 * Key:     PC6(pull-uped)
 * Hys:     PC7
 */
static inline void KEY_ENABLE(void) { (PORTD &= ~(1<<7)); }
static inline void KEY_UNABLE(void) { (PORTD |=  (1<<7)); }
static inline bool KEY_STATE(void) { return (PINC & (1<<6)); }
static inline void KEY_HYS_ON(void) { (PORTC |=  (1<<7)); }
static inline void KEY_HYS_OFF(void) { (PORTC &= ~(1<<7)); }
static inline void KEY_INIT(void)
{
    /* Col */
    DDRB  |=  0x1F;
    /* Key: input with pull-up */
    DDRC  &= ~(1<<6);
    PORTC |=  (1<<6);
    /* Hys */
    DDRC  |=  (1<<7);
    /* Row */
    DDRD  |=  0xF0;

    KEY_UNABLE();
    KEY_HYS_OFF();
}
static inline void SET_ROW(uint8_t ROW)
{
    // set row with unabling key
    PORTD = (PORTD & 0x0F) | (1<<7) | ((ROW & 0x07) << 4);
}
static inline void SET_COL(uint8_t COL)
{
    //         |PB3(Z5 ~EN)|PB4(Z4 ~EN)
    // --------|-----------|-----------
    // Col:0-7 |high       |low
    // Col:8-F |low        |high
    PORTB = (PORTB & 0xE0) | ((COL & 0x08) ? 1<<4 : 1<<3) | (COL & 0x07);
}

static uint32_t matrix_last_modified = 0;

// matrix state buffer(1:on, 0:off)
static matrix_row_t *matrix;
static matrix_row_t *matrix_prev;
static matrix_row_t _matrix0[MATRIX_ROWS];
static matrix_row_t _matrix1[MATRIX_ROWS];



__attribute__ ((weak))
void matrix_init_kb(void) {
    matrix_init_user();
}

__attribute__ ((weak))
void matrix_scan_kb(void) {
    matrix_scan_user();
}

__attribute__ ((weak))
void matrix_init_user(void) {
}

__attribute__ ((weak))
void matrix_scan_user(void) {
}


void matrix_init(void)
{
    KEY_INIT();

    // LEDs on CapsLock and Insert
    DDRB  |= (1<<5) | (1<<6);
    PORTB |= (1<<5) | (1<<6);

    // initialize matrix state: all keys off
    for (uint8_t i=0; i < MATRIX_ROWS; i++) _matrix0[i] = 0x00;
    for (uint8_t i=0; i < MATRIX_ROWS; i++) _matrix1[i] = 0x00;
    matrix = _matrix0;
    matrix_prev = _matrix1;
    matrix_init_kb();
}

uint8_t matrix_scan(void)
{
    matrix_row_t *tmp;

    tmp = matrix_prev;
    matrix_prev = matrix;
    matrix = tmp;

    uint8_t row, col;
    for (col = 0; col < MATRIX_COLS; col++) {
        SET_COL(col);
        for (row = 0; row < MATRIX_ROWS; row++) {
            //KEY_SELECT(row, col);
            SET_ROW(row);
            _delay_us(2);

            // Not sure this is needed. This just emulates HHKB controller's behaviour.
            if (matrix_prev[row] & (1<<col)) {
                KEY_HYS_ON();
            }
            _delay_us(10);

            // NOTE: KEY_STATE is valid only in 20us after KEY_ENABLE.
            // If V-USB interrupts in this section we could lose 40us or so
            // and would read invalid value from KEY_STATE.
            uint8_t last = TIMER_RAW;

            KEY_ENABLE();

            // Wait for KEY_STATE outputs its value.
            _delay_us(2);

            if (KEY_STATE()) {
                matrix[row] &= ~(1<<col);
            } else {
                matrix[row] |= (1<<col);
            }

            // Ignore if this code region execution time elapses more than 20us.
            // MEMO: 20[us] * (TIMER_RAW_FREQ / 1000000)[count per us]
            // MEMO: then change above using this rule: a/(b/c) = a*1/(b/c) = a*(c/b)
            if (TIMER_DIFF_RAW(TIMER_RAW, last) > 20/(1000000/TIMER_RAW_FREQ)) {
                matrix[row] = matrix_prev[row];
            }

            _delay_us(5);
            KEY_HYS_OFF();
            KEY_UNABLE();

            // NOTE: KEY_STATE keep its state in 20us after KEY_ENABLE.
            // This takes 25us or more to make sure KEY_STATE returns to idle state.
            _delay_us(75);
        }
        if (matrix[row] ^ matrix_prev[row]) {
            matrix_last_modified = timer_read32();
        }
    }
    matrix_scan_kb();
    return 1;
}

inline
bool matrix_is_on(uint8_t row, uint8_t col)
{
    return (matrix[row] & ((matrix_row_t)1<<col));
}

inline
matrix_row_t matrix_get_row(uint8_t row) {
    return matrix[row];
}

void matrix_print(void)
{
#if (MATRIX_COLS <= 8)
    print("r/c 01234567\n");
#elif (MATRIX_COLS <= 16)
    print("r/c 0123456789ABCDEF\n");
#elif (MATRIX_COLS <= 32)
    print("r/c 0123456789ABCDEF0123456789ABCDEF\n");
#endif

    for (uint8_t row = 0; row < MATRIX_ROWS; row++) {

#if (MATRIX_COLS <= 8)
        xprintf("%02X: %08b%s\n", row, bitrev(matrix_get_row(row)),
#elif (MATRIX_COLS <= 16)
        xprintf("%02X: %016b%s\n", row, bitrev16(matrix_get_row(row)),
#elif (MATRIX_COLS <= 32)
        xprintf("%02X: %032b%s\n", row, bitrev32(matrix_get_row(row)),
#endif
#ifdef MATRIX_HAS_GHOST
        matrix_has_ghost_in_row(row) ?  " <ghost" : ""
#else
        ""
#endif
        );
    }
}