/*
 * Simple ShiftBrite interface code for remoodlamp firmware
 * Copyright 2012 (C) Johannes Kroll <jkroll at lavabit 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 3 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/>.
 *
 */

#include <avr/interrupt.h>
#include <avr/io.h>
#include <stdint.h>
#include <string.h>
#include <util/delay.h>

// shiftbrites connected to header labeled as 'aux', setup:
// PC0 -> CI (clock)
// PC1 -> LI (latch)
// PC2 -> DI (data)

#define SBCI    PC0
#define SBLI    PC1
#define SBDI    PC2

#define MAXSHIFTBRITES  16


typedef struct rgb
{
    uint16_t r, g, b;   // 10-bit values
} rgb_t;

static volatile rgb_t sb_colors[MAXSHIFTBRITES];

// number of connected shiftbrites
// todo: create a command to make this value configurable
static volatile uint8_t sb_num_shiftbrites= 3;

// toggle the latch so the shiftbrites accept new values
static void sb_toggle_latch(void)
{
    _delay_us(15);
    PORTC|= (1<<PC1);
    _delay_us(15);
    PORTC&= ~(1<<PC1);
}

// shift out one 32-bit shiftbrite register.
static void sb_shiftout(uint32_t val)
{
    //const unsigned clkdelay= 2;
    for(int8_t i= 31; i>=0; i--) {
        //_delay_us(clkdelay);
        PORTC&= ~(1<<PC0);      // clock lo
        if((val>>i)&1)
            PORTC|= (1<<PC2);   // data bit
        else
            PORTC&= ~(1<<PC2);
        //_delay_us(clkdelay);
        PORTC|= (1<<PC0);       // clock hi
    }
}

// shift out all color values to connected shiftbrites
static void sb_update_all_colors(void)
{
    for(int i= sb_num_shiftbrites-1; i>=0; i--)
        sb_shiftout( (uint32_t)sb_colors[i].g | ((uint32_t)sb_colors[i].r<<10) | ((uint32_t)sb_colors[i].b<<20) );
    sb_toggle_latch();
}


// set the color of a shiftbrite.
void sb_setcolor(uint8_t lamp_index, uint8_t r, uint8_t g, uint8_t b)
{
    if(lamp_index>=MAXSHIFTBRITES) return;
    sb_colors[lamp_index].r= r<<2;
    sb_colors[lamp_index].g= g<<2;
    sb_colors[lamp_index].b= b<<2;
    sb_update_all_colors();
}


#if 0
static void tmp_shiftbritetest(void)
{
    sb_shiftout( (uint32_t)(100) | ((uint32_t)(120)<<10) | ((uint32_t)(100)<<20) | ((uint32_t)1<<30) );
    sb_shiftout( (uint32_t)(100) | ((uint32_t)(120)<<10) | ((uint32_t)(100)<<20) | ((uint32_t)1<<30) );
    sb_shiftout( (uint32_t)(100) | ((uint32_t)(120)<<10) | ((uint32_t)(100)<<20) | ((uint32_t)1<<30) );
    _delay_us(15);
    PORTC|= (1<<PC1);
    _delay_us(15);
    PORTC&= ~(1<<PC1);
    sb_shiftout( (uint32_t)(1023) | ((uint32_t)(0)<<10) | ((uint32_t)(0)<<20) );
    sb_shiftout( (uint32_t)(0) | ((uint32_t)(1023)<<10) | ((uint32_t)(0)<<20) );
    sb_shiftout( (uint32_t)(0) | ((uint32_t)(0)<<10) | ((uint32_t)(1023)<<20) );
    _delay_us(15);
    PORTC|= (1<<PC1);
    _delay_us(15);
    PORTC&= ~(1<<PC1);
}
#endif

// write default values to config registers of all shiftbrites
static void sb_set_default_config_values(void)
{
    for(int i= 0; i<sb_num_shiftbrites; i++)
        sb_shiftout( (uint32_t)(100) | ((uint32_t)(120)<<10) | ((uint32_t)(100)<<20) | ((uint32_t)1<<30) );
    sb_toggle_latch();
}

// setup port for shiftbrites
void sb_init(void)
{
    PORTC= 0;
    DDRC= (1<<PC0) | (1<<PC1) | (1<<PC2);
    sb_set_default_config_values();
#if 0
    for(int k= 0; k<1000; k++)
    {
        memset((void*)sb_colors, 0, sizeof(sb_colors));
        sb_setcolor(k%sb_num_shiftbrites, 0xff, 0x00, 0xff);
        _delay_ms(100);
    }
#endif
}