/***************************************************************************
 *   Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO,                    *
 *                         Niccolò Izzo IU2KIN                             *
 *                         Frederik Saraci IU2NRO                          *
 *                         Silvano Seva IU2KWO                             *
 *                         Mathis Schmieder DB9MAT                         *
 *                                                                         *
 *   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.                          *
 *                                                                         *
 *   As a special exception, if other files instantiate templates or use   *
 *   macros or inline functions from this file, or you compile this file   *
 *   and link it with other works to produce a work based on this file,    *
 *   this file does not by itself cause the resulting work to be covered   *
 *   by the GNU General Public License. However the source code for this   *
 *   file must still be made available in accordance with the GNU General  *
 *   Public License. This exception does not invalidate any other reasons  *
 *   why a work based on this file might be covered by the GNU General     *
 *   Public License.                                                       *
 *                                                                         *
 *   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 <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <interfaces/gpio.h>
#include <interfaces/display.h>
#include <interfaces/delays.h>
#include <hwconfig.h>
#include <SPI2.h>

/*
 * LCD framebuffer, allocated on the heap by display_init().
 * Pixel format is black and white, one bit per pixel
 */
static uint8_t *frameBuffer;

void display_init()
{

    /*
     * Framebuffer size, in bytes, with compensating for eventual truncation
     * error in division by rounding to the nearest greater integer.
     */
    unsigned int fbSize = (SCREEN_HEIGHT * SCREEN_WIDTH)/8;
    if((fbSize * 8) < (SCREEN_HEIGHT * SCREEN_WIDTH)) fbSize += 1;
    fbSize *= sizeof(uint8_t);

    /* Allocate framebuffer */
    frameBuffer = (uint8_t *) malloc(fbSize);
    if(frameBuffer == NULL)
    {
        puts("*** LCD ERROR: cannot allocate framebuffer! ***");
        return;
    }

    /* Clear framebuffer, setting all pixels to 0x00 makes the screen white */
    memset(frameBuffer, 0x00, fbSize);

    /*
     * Initialise SPI2 for external flash and LCD
     */
    gpio_setMode(SPI2_CLK, ALTERNATE);
    gpio_setMode(SPI2_SDO, ALTERNATE);
    gpio_setMode(SPI2_SDI, ALTERNATE);
    gpio_setAlternateFunction(SPI2_CLK, 5); /* SPI2 is on AF5 */
    gpio_setAlternateFunction(SPI2_SDO, 5);
    gpio_setAlternateFunction(SPI2_SDI, 5);

    spi2_init();

    /*
     * Initialise GPIOs for LCD control
     */
    gpio_setMode(LCD_CS,  OUTPUT);
    gpio_setMode(LCD_RST, OUTPUT);
    gpio_setMode(LCD_RS,  OUTPUT);

    gpio_setPin(LCD_CS);
    gpio_clearPin(LCD_RS);

    gpio_clearPin(LCD_RST); /* Reset controller                          */
    delayMs(50);
    gpio_setPin(LCD_RST);
    delayMs(50);

    gpio_clearPin(LCD_CS);

    gpio_clearPin(LCD_RS);  /* RS low -> command mode                                   */
    spi2_sendRecv(0xAE);  // SH110X_DISPLAYOFF,                
    spi2_sendRecv(0xd5);  // SH110X_SETDISPLAYCLOCKDIV, 0x51,
    spi2_sendRecv(0x51);
    //spi2_sendRecv(0x20);  // SH110X_MEMORYMODE,                
    spi2_sendRecv(0x81);  // SH110X_SETCONTRAST, 0x4F,  
    spi2_sendRecv(0x4F);
    spi2_sendRecv(0xAD);  // SH110X_DCDC, 0x8A,                
    spi2_sendRecv(0x8A);
    spi2_sendRecv(0xA0);  // SH110X_SEGREMAP,                  
    spi2_sendRecv(0xC0);  // SH110X_COMSCANINC,                
    spi2_sendRecv(0xDC);  // SH110X_SETDISPSTARTLINE, 0x0,     
    spi2_sendRecv(0x00);
    spi2_sendRecv(0xd3);  // SH110X_SETDISPLAYOFFSET, 0x60,    
    spi2_sendRecv(0x60);
    spi2_sendRecv(0xd9);  // SH110X_SETPRECHARGE, 0x22,        
    spi2_sendRecv(0x22);
    spi2_sendRecv(0xdb);  // SH110X_SETVCOMDETECT, 0x35,       
    spi2_sendRecv(0x35);
    spi2_sendRecv(0xa8);  // SH110X_SETMULTIPLEX, 0x3F,        
    spi2_sendRecv(0x3f);
    spi2_sendRecv(0xa4);  // SH110X_DISPLAYALLON_RESUME, 	    
    spi2_sendRecv(0xa6);  // SH110X_NORMALDISPLAY,                 	
    spi2_sendRecv(0xAF);  // SH110x_DISPLAYON
    gpio_setPin(LCD_CS);
}

void display_terminate()
{
    if(frameBuffer != NULL)
    {
        free(frameBuffer);
    }

    spi2_terminate();
}

void display_renderRow(uint8_t row)
{
    uint8_t *buf = (frameBuffer);

	for(uint16_t i=0; i<64; i++)
	{
		uint8_t out=0, tmp=buf[i*16 + 15-row];

		for(uint8_t j=0; j<8; j++)
		{
			out|=((tmp>>(7-j))&1)<<j;
		}
			
		spi2_sendRecv(out);
	}
}

void display_renderRows(uint8_t startRow, uint8_t endRow)
{
    gpio_clearPin(LCD_CS);
 
    for(uint8_t row = startRow; row <= endRow; row++)
    {
        gpio_clearPin(LCD_RS);            /* RS low -> command mode */
        (void) spi2_sendRecv(0xB0 | row); /* Set Y position         */
        (void) spi2_sendRecv(0x00);       /* Set X position         */
        (void) spi2_sendRecv(0x10);
        gpio_setPin(LCD_RS);              /* RS high -> data mode   */
        display_renderRow(row);
    }
 
    gpio_setPin(LCD_CS);
}

void display_render()
{
    display_renderRows(0, SCREEN_WIDTH / 8 - 1);
}

bool display_renderingInProgress()
{
    return (gpio_readPin(LCD_CS) == 0);
}

void *display_getFrameBuffer()
{
    return (void *)(frameBuffer);
}

void display_setContrast(uint8_t contrast)
{
    gpio_clearPin(LCD_CS);

    gpio_clearPin(LCD_RS);             /* RS low -> command mode              */
    (void) spi2_sendRecv(0x81);        /* Set Electronic Volume               */
    (void) spi2_sendRecv(contrast);    /* Controller contrast range is 0 - 63 */

    gpio_setPin(LCD_CS);
}