/** \file

  \brief Code specific to the SSD1306 display.
*/

#include "display.h"

#if defined TEACUP_C_INCLUDE && defined DISPLAY_TYPE_SSD1306

#include "displaybus.h"
#include "font.h"


static const uint8_t PROGMEM init_sequence[] = {
  0x00,             // Command marker.
  0xAE,             // Display off.
  0xD5, 0x80,       // Display clock divider (reset).
  0xA8, 0x1F,       // 1/32 duty.
  0x40 | 0x00,      // Start line (reset).
  0x20, 0x02,       // Page addressing mode (reset).
  0x22, 0x00, 0x03, // Start and end page in horiz./vert. addressing mode[1].
  0x21, 0x00, 0x7F, // Start and end column in horiz./vert. addressing mode.
  0xA0 | 0x00,      // No segment remap (reset).
  0xC0 | 0x00,      // Normal com pins mapping (reset).
  0xDA, 0x02,       // Sequental without remap com pins.
  0x81, 0x7F,       // Contrast (reset).
  0xDB, 0x20,       // Vcomh (reset).
  0xD9, 0xF1,       // Precharge period.
  0x8D, 0x14,       // Charge pump.
  0xA6,             // Positive display.
  0xA4,             // Resume display.
  0xAF              // Display on.
};
// [1] Do not set this to 0x00..0x07 on a 32 pixel high display, or vertical
//     addressing mode will mess up. 32 pixel high displays have only 4 pages
//     (0..3), still addressing logic accepts, but can't deal with the 0..7
//     meant for 64 pixel high displays.

/**
 * Initializes the display's controller configuring the way of
 * displaying data.
 */
void display_init(void) {
  uint8_t i;

  displaybus_init(DISPLAY_I2C_ADDRESS);

  for (i = 0; i < sizeof(init_sequence); i++) {
    // Send last byte with 'last_byte' set.
    displaybus_write(init_sequence[i], (i == sizeof(init_sequence) - 1));
  }
}

/**
  Clear the screen. As this display supports many sophisticated commands,
  but not a simple 'clear', we have to overwrite the entire memory with
  zeros, byte by byte.
*/
void display_clear(void) {
  uint16_t i;

  // Set horizontal adressing mode.
  displaybus_write(0x00, 0);
  displaybus_write(0x20, 0);
  displaybus_write(0x00, 1);

  // Write 512 zeros.
  displaybus_write(0x40, 0);
  for (i = 0; i < 512; i++) {
    displaybus_write(0x00, (i == 511));
  }

  // Return to page adressing mode.
  displaybus_write(0x00, 0);
  displaybus_write(0x20, 0);
  displaybus_write(0x02, 1);
}

/**
  Prints the text at a given position.
*/
void display_text_P(uint8_t line, uint8_t column, PGM_P message) {
  uint8_t i, index;

  // Enter command mode.
  displaybus_write(0x00, 0);
  // Set line.
  displaybus_write(0xB0 | (line & 0x03), 0);
  // Set column.
  displaybus_write(0x00 | (column & 0x0F), 0);
  displaybus_write(0x10 | ((column >> 4) & 0x0F), 1);

  // Render text to bitmap to display.
  displaybus_write(0x40, 0);
  while ((index = pgm_read_byte(message))) {
    index -= 0x20;

    // Send the character bitmap.
    #ifdef FONT_IS_PROPORTIONAL
      for (i = 0; i < pgm_read_byte(&font[index].columns); i++) {
    #else
      for (i = 0; i < FONT_COLUMNS; i++) {
    #endif
        displaybus_write(pgm_read_byte(&font[index].data[i]), 0);
    }
    // Send space between characters.
    for (i = 0; i < FONT_SYMBOL_SPACE; i++) {
      displaybus_write(0x00, 0);
    }

    message++;
  }
  // Send another space for transmission end.
  displaybus_write(0x00, 1);
}

#endif /* TEACUP_C_INCLUDE && DISPLAY_TYPE_SSD1306 */