#include <inttypes.h>

//! How far can the LCD state be pushed
//! \ingroup lcd
#define LCD_STATE_DEPTH  3


#define LCD_REG_COMMAND  0

//! LCD State
//! \ingroup lcd
struct _lcd_state_t {
    uint8_t    x;        //!< The X position of the cursor
    uint8_t    y;        //!< The Y position of the cursor
    uint8_t    flags;    //!< The state flags (backlight, blink)
    float      contrast; //!< The contrast level
};
typedef struct _lcd_state_t lcd_state_t;

typedef struct _lcd_dvr_t lcd_dvr_t;

/*! \struct lcd_dvr_t lcd.h <utos/lcd.h>
 This structure defines the geometry and hardware specific operations of
 the LCD.

 \ingroup lcd
*/
struct _lcd_dvr_t {
   /*!
     Initialize the LCD hardware.  This includes setup data direction,
     and bring the LCD into a state where lcd_in() and lcd_out driver
     calls will work.  Also do any contrast and backlight initialization.

     \param dvr Pointer to "this" driver.
     \return 0 if successful initializtion.  non-zero on error.
   */
   int8_t      (*init)(lcd_dvr_t *);
   /*!
    Read a byte from the LCD.  Select data or command register.

    \param reg LCD_DATA or LCD_COMMAND
    \return The data read
   */
   uint8_t     (*in)(uint8_t reg);
   /*!
    Write a byte to the LCD.  Select data or command register

    \param reg LCD_DATA or LCD_COMMAND
   */
   void        (*out)(uint8_t reg, uint8_t dat);
   /*!
    Do what is necessary to set the state of the backlight to on

    \param on The new state of the backlight (LCD_BACKLIGHT_ON or LCD_BACKLIGHT_OFF)
   */
   void        (*backlight)(uint8_t on);
   /*!
    The LCD contrast is internally represented as a float.  The hardware needs
    to do its best interpolation of the contrast value when setting the contrast.

    \param c The new contrast
   */
   void        (*contrast)(float c);

   /*!
    Set by the caller.  These values are used to calculate offsets when placing text.
   */
   uint8_t     rows;
   uint8_t     cols;

   /*!
    The state of the LCD.
   */
   lcd_state_t state[LCD_STATE_DEPTH];
   uint8_t     state_idx;
   uint8_t     check;
};

static inline uint8_t lcd_busy(lcd_dvr_t *lcd)
{
    return lcd->check && (lcd->in(LCD_REG_COMMAND) & 0x80);
}

static inline void lcd_command(lcd_dvr_t *lcd, uint8_t c)
{
    while (lcd_busy(lcd))
        /* do nothing */ ;
    lcd->out(LCD_REG_COMMAND, c);
}

void lcd_set_cgram_ptr(lcd_dvr_t *lcd, uint8_t idx)
{
    lcd_command(lcd, 0x40 + idx * 8);
}