/***************************************************************************
 *   Copyright (C) 2021 - 2022 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.                          *
 *                                                                         *
 *   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, statically allocated and placed in the "large" RAM block
 * starting at 0x20000000.
 * Pixel format is black and white, one bit per pixel.
 */
#define FB_SIZE (((SCREEN_HEIGHT * SCREEN_WIDTH) / 8 ) + 1)
static uint8_t __attribute__((section(".bss2"))) frameBuffer[FB_SIZE];


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

    /*
     * 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(0x81);    /* SH110X_SETCONTRAST, 0x4F        */
    spi2_sendRecv(0x4F);
    spi2_sendRecv(0xAD);    /* SH110X_DCDC, 0x8A               */
    spi2_sendRecv(0x8A);
    spi2_sendRecv(0xA1);    /* 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()
{
    spi2_terminate();
}

void display_renderRows(uint8_t startRow, uint8_t endRow)
{
    gpio_clearPin(LCD_CS);

    for(uint8_t y = startRow; y < endRow; y++)
    {
        for(uint8_t x = 0; x < SCREEN_WIDTH/8; x++)
        {
            gpio_clearPin(LCD_RS);              /* RS low -> command mode */
            (void) spi2_sendRecv(y & 0x0F);     /* Set Y position         */
            (void) spi2_sendRecv(0x10 | ((y >> 4) & 0x07));
            (void) spi2_sendRecv(0xB0 | x);     /* Set X position         */
            gpio_setPin(LCD_RS);                /* RS high -> data mode   */

            size_t pos = x + y * (SCREEN_WIDTH/8);
            spi2_sendRecv(frameBuffer[pos]);
        }
    }

    gpio_setPin(LCD_CS);
}

void display_render()
{
    display_renderRows(0, SCREEN_HEIGHT);
}

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);
}