/** \file

  \brief Display broker.

  Here we map generic display calls to calls to the actually used display and
  also define functions common to all displays.
*/

#include "display.h"

#ifdef DISPLAY

// Ringbuffer logic for buffer 'display'.
#define BUFSIZE DISPLAY_BUFFER_SIZE

volatile uint8_t displayhead = 0;
volatile uint8_t displaytail = 0;
volatile uint8_t displaybuf[BUFSIZE];

#include "ringbuffer.h"


#define TEACUP_C_INCLUDE
  #include "display_ssd1306.c"
  #include "display_hd44780.c"
#undef TEACUP_C_INCLUDE


#include "delay.h"

/**
  Queue up a clear screen command. Very cheap operation on some displays, like
  the HD44780, rather expensive on others, like the SSD1306.
*/
void display_clear(void) {
  display_writechar((uint8_t)low_code_clear);
}

/**
  Prints a character at the current cursor position.

  \param data The character to be displayed.

  This code is identical for all display buses and display types, because it
  just queues up the character.

  In case the buffer is full already it waits for a millisecond to allow
  data to be sent to the display, then it tries again. If it still fails then,
  it drops the character. This way we're fairly protected against data loss,
  still we guarantee to not hang forever.
*/
void display_writechar(uint8_t data) {

  if ( ! buf_canwrite(display)) {
    delay_ms(1);
  }
  if (buf_canwrite(display)) {
    buf_push(display, data);
  }
}

void display_writestr_P(PGM_P data_P) {
  uint8_t r, i = 0;

  // Yes, this is *supposed* to be assignment rather than comparison, so we
  // break when r is assigned zero.
  while ((r = pgm_read_byte(&data_P[i]))) {
    display_writechar(r);
    i++;
  }
}

#endif /* DISPLAY */