#include "project.h"

#define FOO do { printf("lcd:%x\r\n",__LINE__); usart1_drain(); } while (0)

#define PCF8574_I2C_ADDRESS 0x27

#define LINE_RS		0x1
#define LINE_RnW	0x2
#define LINE_EN		0x4
#define LINE_BACKLIGHT	0x8

#define LCD_CLEAR	0x1
#define LCD_HOME	0x2

#define LCD_DISP 	0x8
#define LCD_DISP_ON 	0x4
#define LCD_DISP_CURSOR 0x2
#define LCD_DISP_CURSOR_BLINK 0x1

#define LCD_FUNC        0x20
#define LCD_FUNC_8BIT   0x10
#define LCD_FUNC_4BIT	0x00
#define LCD_FUNC_2ROWS	0x08
#define LCD_FUNC_1ROW 	0x00
#define LCD_FUNC_5x10 	0x04
#define LCD_FUNC_5X7	0x00

#define LCD_SET_DDRAM_ADDR 0x80

#define LCD_H_SHIFT 5
#define LCD_RS (1 << LCD_H_SHIFT)
#define LCD_W 16
#define LCD_W_MASK (LCD_RS -1 )
#define LCD_H 2
#define LCD_SZ (LCD_H << LCD_H_SHIFT)
#define LCD_POS(c,r) (((r) << LCD_H_SHIFT ) +(c))

#define BYTES_PER_BYTE 6

#define DMA_BUF_SZ (BYTES_PER_BYTE * ( (1 + LCD_W) *LCD_H  + 1))

static uint8_t dma_buf[DMA_BUF_SZ];
static uint8_t update_buf[DMA_BUF_SZ];
static volatile int dma_in_progress = 0;
static int refresh_enabled = 0;

static int backlight;
static int pos;

static void
clock_nibble (uint8_t n)
{
  if (backlight)
    n |= LINE_BACKLIGHT;
  i2cp_send_data (n);
  i2cp_send_data (LINE_EN | n);
  i2cp_send_data (n);
}


static void
write_reg (uint8_t c, int r)
{
  uint8_t b;

  b = c & 0xf0;
  if (r)
    b |= LINE_RS;

  clock_nibble (b);

  b = (c & 0xf) << 4;
  if (r)
    b |= LINE_RS;

  clock_nibble (b);
}

static void
send_command (uint8_t c)
{
  write_reg (c, 0);
}

static void
send_one_command (uint8_t cmd, int delay)
{
  while (i2cp_lock ());
  i2cp_start_transaction (PCF8574_I2C_ADDRESS, I2C_WRITE);
  send_command (cmd);
  i2cp_stop ();
  if (delay)
    delay_ms (delay);
  i2cp_unlock ();
}



static void
cls (void)
{
  send_one_command (LCD_CLEAR, 2);
}

#if 0
static void
home (void)
{
  send_one_command (LCD_HOME, 2);
}
#endif

static void
on (void)
{
  send_one_command (LCD_DISP | LCD_DISP_ON /* | LCD_DISP_CURSOR */ , 4);
}

static void
off (void)
{
  send_one_command (LCD_DISP, 4);
}

static int
lcd_addr (int x, int y)
{
  return x + ((y & 1) << 6) + ((y & 2) ? 20 : 0);
}


#if 0
static void
move (uint8_t c, uint8_t r)
{
  send_one_command (LCD_SET_DDRAM_ADDR | lcd_addr (c, r), 2);
}
#endif


uint32_t refresh_wdt = 0;

static void
start_dma (void)
{
  if (dma_in_progress)
    return;

  refresh_wdt = 0;

  dma_in_progress = 1;

  memcpy (dma_buf, update_buf, DMA_BUF_SZ);
  i2cp_start_transaction (PCF8574_I2C_ADDRESS, I2C_WRITE);
  i2cp_start_dma (dma_buf, DMA_BUF_SZ);

}

void
dma1_channel6_isr (void)
{
  if (dma_in_progress)
    {
      i2cp_stop_dma ();

      i2cp_stop ();
      dma_in_progress = 0;
    }

  if (refresh_enabled)
    start_dma ();
}

void
lcd_refresh_wdt (void)
{
  refresh_wdt++;

  if (refresh_wdt < 1000)
    return;

  refresh_wdt = 0;

  if (!refresh_enabled) return;

/*No refresh for 1s, restart everything */

  i2cp_stop_dma ();
  i2cp_stop ();
  dma_in_progress = 0;

  start_dma ();

}

static inline void
dma_clock_nibble (uint8_t * ptr, uint8_t n)
{
  if (backlight)
    n |= LINE_BACKLIGHT;
  *(ptr++) = n;
  *(ptr++) = n | LINE_EN;
  *(ptr++) = n;
}


static inline int
dma_write_reg (uint8_t * ptr, uint8_t c, int r)
{
  uint8_t b;

  b = c & 0xf0;
  if (r)
    b |= LINE_RS;

  dma_clock_nibble (ptr, b);
  ptr += 3;

  b = (c & 0xf) << 4;
  if (r)
    b |= LINE_RS;

  dma_clock_nibble (ptr, b);

  return 6;
}

static inline int
dma_command (uint8_t * ptr, uint8_t c)
{
  return dma_write_reg (ptr, c, 0);
}

static inline int
dma_data (uint8_t * ptr, uint8_t c)
{
  return dma_write_reg (ptr, c, 1);
}


static void
dma_generate_stream (void)
{
  uint8_t *dma_ptr;
  int x, y, i;

  dma_ptr = update_buf;
/* 6 bytes per character, 6 bytes to move position, 5 moves + 20*4 chars => 510*/

  for (y = 0; y < LCD_H; ++y)
    {

      dma_ptr += dma_command (dma_ptr, LCD_SET_DDRAM_ADDR | lcd_addr (0, y));

      i = y << LCD_H_SHIFT;

      for (x = 0; x < LCD_W; ++x, i++)
        {
          dma_ptr += dma_data (dma_ptr, ' ');
        }
    }

  dma_ptr += dma_command (dma_ptr, LCD_SET_DDRAM_ADDR |
                          lcd_addr (pos & LCD_W_MASK, pos >> LCD_H_SHIFT));

}


static void
dma_change_backlight (void)
{
  int len = DMA_BUF_SZ;
  uint8_t *p = update_buf;

  cm_disable_interrupts ();

  if (backlight)
    while (p++, len--)
      *p |= LINE_BACKLIGHT;
  else
    while (p++, len--)
      *p &= ~LINE_BACKLIGHT;

  cm_enable_interrupts ();
}


static int
dma_offset (int x, int y)
{
  return BYTES_PER_BYTE * (1 + x + y * (LCD_W + 1));
}



static void
_lcd_write_char (uint8_t c, int x, int y)
{
  cm_disable_interrupts ();
  dma_data (update_buf + dma_offset (x, y), c);
  cm_enable_interrupts ();
}


void
lcd_write_char (uint8_t c, int x, int y)
{
  cm_disable_interrupts ();
  _lcd_write_char (c, x, y);
  cm_enable_interrupts ();
}


void
lcd_erase (int x, int y, int w)
{
  uint8_t *dma_ptr = update_buf + dma_offset (x, y);
  cm_disable_interrupts ();
  while (w--)
    dma_ptr += dma_data (dma_ptr, ' ');
  cm_enable_interrupts ();
}

void
lcd_erase_line (int w, int y)
{
  lcd_erase (0, y, w);
}

void
lcd_erase_all (void)
{
  int y;
  for (y = 0; y < LCD_H; ++y)
    {
      lcd_erase (0, 0, LCD_W);
    }
}

void
lcd_write (char *c, int x, int y)
{
  cm_disable_interrupts ();
  while (*c)
    {
      _lcd_write_char (*(c++), x++, y);
      if (x == LCD_W)
        break;
    }
  cm_enable_interrupts ();
}

#if 0
static void
lcd_scroll (uint8_t * p)
{
  int i;
  for (i = 0; i < 3; ++i)
    {
      memcpy (p, p + LCD_RS, LCD_W);
      p += LCD_RS;
    }
  memset (p, ' ', LCD_W);
}

void
lcd_putc (uint8_t c)
{

  switch (c)
    {
    case '\r':
      pos &= ~LCD_W_MASK;
      break;
    case '\n':
      pos &= ~LCD_W_MASK;
      pos += LCD_RS;
      break;
    default:
      buf[pos] = c;
      pos++;
    }


  if ((pos & LCD_W_MASK) == LCD_W)
    {
      pos &= ~LCD_W_MASK;
      pos += LCD_RS;
    }

  if (pos == LCD_SZ)
    {
      lcd_scroll (buf);
      pos -= LCD_RS;
    }


}
#endif


void
lcd_backlight (int i)
{
  backlight = i;

  dma_change_backlight ();

  if (refresh_enabled)
    return;

  while (i2cp_lock ());
  i2cp_start_transaction (PCF8574_I2C_ADDRESS, I2C_WRITE);
  i2cp_send_data (backlight ? LINE_BACKLIGHT : 0);
  i2cp_stop ();
  i2cp_unlock ();
}





void
lcd_enable_refresh ()
{
  refresh_enabled = 1;
  start_dma ();
}


int
lcd_disable_refresh (void)
{
  int ret;
  if (!refresh_enabled) return 0;
  ret=refresh_enabled;
  refresh_enabled = 0;
  while (dma_in_progress);

  return ret;
}



void
lcd_reset (void)
{
  while (i2cp_lock ());
  i2cp_start_transaction (PCF8574_I2C_ADDRESS, I2C_WRITE);
  clock_nibble (0x30);
  delay_ms (5);
  clock_nibble (0x30);
  delay_us (64);
  clock_nibble (0x30);
  delay_us (64);
  clock_nibble (0x20);

  send_command (LCD_FUNC | LCD_FUNC_4BIT | LCD_FUNC_2ROWS | LCD_FUNC_5X7);
  i2cp_stop ();
  i2cp_unlock ();

  on ();
  cls ();
}

void
lcd_init (void)
{
  lcd_backlight (0);
  lcd_reset ();
  lcd_backlight (1);

  dma_generate_stream ();

  nvic_enable_irq (NVIC_DMA1_CHANNEL6_IRQ);
  lcd_enable_refresh ();
}

void
lcd_shutdown (void)
{
  lcd_disable_refresh ();
  lcd_backlight (0);
  off ();
}