/*! @file LCD.c

  @brief
  @author  Hendrik Schutter
  @version V1.0
  @date    03.11.2020

*/


#include "LCD.h"
#include "Driver.h"

/*
 This code displays some fancy graphics on the 320x240 LCD on an ESP-WROVER_KIT board.
 This example demonstrates the use of both spi_device_transmit as well as
 spi_device_queue_trans/spi_device_get_trans_result and pre-transmit callbacks.

 Some info about the ILI9341/ST7789V: It has an C/D line, which is connected to a GPIO here. It expects this
 line to be low for a command and high for data. We use a pre-transmit callback here to control that
 line: every transaction has as the user-definable argument the needed state of the D/C line and just
 before the transaction is sent, the callback will set this line to the correct state.
*/

esp_err_t allocate_frame_buffer(uint16_t ***pPixels);
void write_framebuffer(spi_device_handle_t* spi);

uint16_t **pixels; //framebuffer
spi_device_handle_t spi;

    uint16_t *lines[2];


    //Indexes of the line currently being sent to the LCD and the line we're calculating.
    int sending_line=-1;
    int calc_line=0;

void vLCD_init(void) {

    esp_err_t ret;
    
    spi_bus_config_t buscfg= {
        .miso_io_num=PIN_NUM_MISO,
        .mosi_io_num=PIN_NUM_MOSI,
        .sclk_io_num=PIN_NUM_CLK,
        .quadwp_io_num=-1,
        .quadhd_io_num=-1,
        .max_transfer_sz=PARALLEL_LINES*320*2+8
    };
    spi_device_interface_config_t devcfg= {
#ifdef CONFIG_LCD_OVERCLOCK
        .clock_speed_hz=26*1000*1000,           //Clock out at 26 MHz
#else
        .clock_speed_hz=10*1000*1000,           //Clock out at 10 MHz
#endif
        .mode=0,                                //SPI mode 0
        .spics_io_num=PIN_NUM_CS,               //CS pin
        .queue_size=7,                          //We want to be able to queue 7 transactions at a time
        .pre_cb=vDriver_spi_pre_transfer_callback,  //Specify pre-transfer callback to handle D/C line
    };
    //Initialize the SPI bus
    ret=spi_bus_initialize(LCD_HOST, &buscfg, DMA_CHAN);
    ESP_ERROR_CHECK(ret);
    //Attach the LCD to the SPI bus
    ret=spi_bus_add_device(LCD_HOST, &devcfg, &spi);
    ESP_ERROR_CHECK(ret);
    //Initialize the LCD
    vDriver_init(spi);

    //Initialize the framebuffer
    ret=allocate_frame_buffer(&pixels);
    ESP_ERROR_CHECK(ret);
    
    
        //Allocate memory for the pixel buffers
    for (int i=0; i<2; i++) {
        lines[i]=heap_caps_malloc(320*PARALLEL_LINES*sizeof(uint16_t), MALLOC_CAP_DMA);
        assert(lines[i]!=NULL);
    }

}

/* To send a set of lines we have to send a command, 2 data bytes, another command, 2 more data bytes and another command
 * before sending the line data itself; a total of 6 transactions. (We can't put all of this in just one transaction
 * because the D/C line needs to be toggled in the middle.)
 * This routine queues these commands up as interrupt transactions so they get
 * sent faster (compared to calling spi_device_transmit several times), and at
 * the mean while the lines for next transactions can get calculated.
 */
static void send_lines(spi_device_handle_t spi, int ypos, uint16_t *linedata)
{
    esp_err_t ret;
    int x;
    //Transaction descriptors. Declared static so they're not allocated on the stack; we need this memory even when this
    //function is finished because the SPI driver needs access to it even while we're already calculating the next line.
    static spi_transaction_t trans[6];

    //In theory, it's better to initialize trans and data only once and hang on to the initialized
    //variables. We allocate them on the stack, so we need to re-init them each call.
    for (x=0; x<6; x++) {
        memset(&trans[x], 0, sizeof(spi_transaction_t));
        if ((x&1)==0) {
            //Even transfers are commands
            trans[x].length=8;
            trans[x].user=(void*)0;
        } else {
            //Odd transfers are data
            trans[x].length=8*4;
            trans[x].user=(void*)1;
        }
        trans[x].flags=SPI_TRANS_USE_TXDATA;
    }
    trans[0].tx_data[0]=0x2A;           //Column Address Set
    trans[1].tx_data[0]=0;              //Start Col High
    trans[1].tx_data[1]=0;              //Start Col Low
    trans[1].tx_data[2]=(320)>>8;       //End Col High
    trans[1].tx_data[3]=(320)&0xff;     //End Col Low
    trans[2].tx_data[0]=0x2B;           //Page address set
    trans[3].tx_data[0]=ypos>>8;        //Start page high
    trans[3].tx_data[1]=ypos&0xff;      //start page low
    trans[3].tx_data[2]=(ypos+PARALLEL_LINES)>>8;    //end page high
    trans[3].tx_data[3]=(ypos+PARALLEL_LINES)&0xff;  //end page low
    trans[4].tx_data[0]=0x2C;           //memory write
    trans[5].tx_buffer=linedata;        //finally send the line data
    trans[5].length=320*2*8*PARALLEL_LINES;          //Data length, in bits
    trans[5].flags=0; //undo SPI_TRANS_USE_TXDATA flag

    //Queue all transactions.
    for (x=0; x<6; x++) {
        ret=spi_device_queue_trans(spi, &trans[x], portMAX_DELAY);
        assert(ret==ESP_OK);
    }

    //When we are here, the SPI driver is busy (in the background) getting the transactions sent. That happens
    //mostly using DMA, so the CPU doesn't have much to do here. We're not going to wait for the transaction to
    //finish because we may as well spend the time calculating the next line. When that is done, we can call
    //send_line_finish, which will wait for the transfers to be done and check their status.
}


static void send_line_finish(spi_device_handle_t spi)
{
    spi_transaction_t *rtrans;
    esp_err_t ret;
    //Wait for all 6 transactions to be done and get back the results.
    for (int x=0; x<6; x++) {
        ret=spi_device_get_trans_result(spi, &rtrans, portMAX_DELAY);
        assert(ret==ESP_OK);
        //We could inspect rtrans now if we received any info back. The LCD is treated as write-only, though.
    }
}


esp_err_t allocate_frame_buffer(uint16_t ***pPixels)
{
    *pPixels = NULL;
    esp_err_t ret = ESP_OK;

    //Alocate pixel memory. Each line is an array of IMAGE_W 16-bit pixels; the `*pixels` array itself contains pointers to these lines.
    *pPixels = calloc(240, sizeof(uint16_t *));
    if (*pPixels == NULL) {
        printf("Error allocating memory for lines");
        ret = ESP_ERR_NO_MEM;
    }
    for (int i = 0; i < 240; i++) {
        (*pPixels)[i] = malloc(320 * sizeof(uint16_t));
        if ((*pPixels)[i] == NULL) {
            printf("Error allocating memory for line %d", i);
            ret = ESP_ERR_NO_MEM;
        }
    }
    return ret;
} //end fun

//Calculate the pixel data for a set of lines (with implied line size of 320). Pixels go in dest, line is the Y-coordinate of the
//first line to be calculated, linect is the amount of lines to calculate. Frame increases by one every time the entire image
//is displayed; this is used to go to the next frame of animation.
void get_framenuffer_per_line(uint16_t *dest, int line, int linect)
{
    for (int y=line; y<line+linect; y++) {
        for (int x=0; x<320; x++) {
            *dest++=pixels[y][x];
        }
    }
}


void clear_framebuffer(uint16_t u16Color) {
    // uint8_t *in = (uint8_t *)bitmap;
    for (int y = 0; y < 240; y++) {
        for (int x = 0; x < 320; x++) {
            //The LCD wants the 16-bit value in big-endian, so swap bytes
            u16Color = (u16Color >> 8) | (u16Color << 8);
            pixels[y][x] = u16Color;
        }
    }

    write_framebuffer(&spi);

}

void write_framebuffer(spi_device_handle_t* spi) {

    
    for (int y=0; y<240; y+=PARALLEL_LINES) {
        //Calculate a line.
        get_framenuffer_per_line(lines[calc_line], y, PARALLEL_LINES);
        //Finish up the sending process of the previous line, if any
        if (sending_line!=-1) 
        {
            send_line_finish(*spi);
        }
        //Swap sending_line and calc_line
        sending_line=calc_line;
        calc_line=(calc_line==1)?0:1;
        //Send the line we currently calculated.
        send_lines(*spi, y, lines[sending_line]);
        //The line set is queued up for sending now; the actual sending happens in the
        //background. We can go on to calculate the next line set as long as we do not
        //touch line[sending_line]; the SPI sending process is still reading from that.
    }
}