/*

  u8x8_8x8.c
  
  font procedures, directly interfaces display procedures
  
  Universal 8bit Graphics Library (https://github.com/olikraus/u8g2/)

  Copyright (c) 2016, olikraus@gmail.com
  All rights reserved.

  Redistribution and use in source and binary forms, with or without modification, 
  are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice, this list 
    of conditions and the following disclaimer.
    
  * Redistributions in binary form must reproduce the above copyright notice, this 
    list of conditions and the following disclaimer in the documentation and/or other 
    materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
  CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, 
  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.    

*/

#include "u8x8.h"




void u8x8_SetFont(u8x8_t *u8x8, const uint8_t *font_8x8)
{
  u8x8->font = font_8x8;
}

void u8x8_DrawGlyph(u8x8_t *u8x8, uint8_t x, uint8_t y, uint8_t encoding)
{
  uint8_t first, last, i;
  uint8_t buf[8];
  uint16_t offset;
  first = u8x8_pgm_read(u8x8->font+0);
  last = u8x8_pgm_read(u8x8->font+1);
  
  if ( first <= encoding && encoding <= last )
  {
    offset = encoding;
    offset -= first;
    offset *= 8;
    offset +=2;
    for( i = 0; i < 8; i++ )
    {
      buf[i] = u8x8_pgm_read(u8x8->font+offset);
      offset++;
    }
  }
  else
  {
    for( i = 0; i < 8; i++ )
    {
      buf[i] = 0;
    }
  }
  if ( u8x8->is_font_inverse_mode )
  {
    for( i = 0; i < 8; i++ )
    {
      buf[i] ^= 255;
    }
  }
  u8x8_DrawTile(u8x8, x, y, 1, buf);
}

/*
source: https://en.wikipedia.org/wiki/UTF-8
Bits	from 		to			bytes	Byte 1 		Byte 2 		Byte 3 		Byte 4 		Byte 5 		Byte 6
  7 	U+0000 		U+007F 		1 		0xxxxxxx
11 	U+0080 		U+07FF 		2 		110xxxxx 	10xxxxxx
16 	U+0800 		U+FFFF 		3 		1110xxxx 	10xxxxxx 	10xxxxxx
21 	U+10000 	U+1FFFFF 	4 		11110xxx 	10xxxxxx 	10xxxxxx 	10xxxxxx
26 	U+200000 	U+3FFFFFF 	5 		111110xx 	10xxxxxx 	10xxxxxx 	10xxxxxx 	10xxxxxx
31 	U+4000000 	U+7FFFFFFF 	6 		1111110x 	10xxxxxx 	10xxxxxx 	10xxxxxx 	10xxxxxx 	10xxxxxx  

This function returns 0x0ffff for end of string (0x0ffff is not a unicode glyph)

*/
#ifdef OBSOLETE
uint16_t u8x8_get_encoding_from_utf8_string(const char **str) 
{
  uint16_t e;
  uint8_t b;
  b = **str;
  if ( b >= 0xc0 )
  {
    if ( b >= 0xf0 )	/* check for UTF-8 4, 5 and 6-byte sequence */
    {
      b &= 0x01;	/* only consider lowest bit, because only plane 0 (16 bit) is supported with u8glib v2 */
    }
    else if ( b >= 0xe0 )	/* check for UTF-8 3-byte sequence */
    {
      b &= 0x0f;
    }
    else /* assume UTF-8 2-byte sequence */
    {
      b &= 0x1f;
    }
    e = b;    
    for(;;)
    {
      (*str)++;
      b = **str;
      if ( (b & 0x0c0) != 0x080 )
	break;
      b &= 0x3f;
      e <<=6;
      e |= b;
    }      
  }
  else
  {
    e = b;		/* init with ASCII code */
    (*str)++;
  }
  return e;
}
#endif

/* reset the internal state machine */
void u8x8_utf8_init(u8x8_t *u8x8)
{
  u8x8->utf8_state = 0;	/* also reset during u8x8_SetupDefaults() */
}

uint16_t u8x8_ascii_next(u8x8_t *u8x8, uint8_t b)
{
  if ( b == 0 || b == '\n' ) /* '\n' terminates the string to support the string list procedures */
    return 0x0ffff;	/* end of string detected*/
  return b;
}

/*
  pass a byte from an utf8 encoded string to the utf8 decoder state machine
  returns 
    0x0fffe: no glyph, just continue
    0x0ffff: end of string
    anything else: The decoded encoding
*/
uint16_t u8x8_utf8_next(u8x8_t *u8x8, uint8_t b)
{
  if ( b == 0 || b == '\n' )	/* '\n' terminates the string to support the string list procedures */
    return 0x0ffff;	/* end of string detected, pending UTF8 is discarded */
  if ( u8x8->utf8_state == 0 )
  {
    if ( b >= 0xfc )	/* 6 byte sequence */
    {
      u8x8->utf8_state = 5;
      b &= 1;
    }
    else if ( b >= 0xf8 )
    {
      u8x8->utf8_state = 4;
      b &= 3;
    }
    else if ( b >= 0xf0 )
    {
      u8x8->utf8_state = 3;
      b &= 7;      
    }
    else if ( b >= 0xe0 )
    {
      u8x8->utf8_state = 2;
      b &= 15;
    }
    else if ( b >= 0xc0 )
    {
      u8x8->utf8_state = 1;
      b &= 0x01f;
    }
    else
    {
      /* do nothing, just use the value as encoding */
      return b;
    }
    u8x8->encoding = b;
    return 0x0fffe;
  }
  else
  {
    u8x8->utf8_state--;
    /* The case b < 0x080 (an illegal UTF8 encoding) is not checked here. */
    u8x8->encoding<<=6;
    b &= 0x03f;
    u8x8->encoding |= b;
    if ( u8x8->utf8_state != 0 )
      return 0x0fffe;	/* nothing to do yet */
  }
  return u8x8->encoding;
}


#ifdef OBSOLETE
uint16_t u8x8_get_char_from_string(const char **str)
{
  uint8_t b = **str;
  (*str)++;
  return b; 
}

static uint8_t u8x8_draw_string(u8x8_t *u8x8, uint8_t x, uint8_t y, const char *s) U8X8_NOINLINE;
static uint8_t u8x8_draw_string(u8x8_t *u8x8, uint8_t x, uint8_t y, const char *s)
{
  uint16_t c;
  uint8_t cnt = 0;
  for(;;)
  {
    c = u8x8->char_cb(&s);
    if ( c == 0 )
      break;
    if ( c <= 255 )
    {
      u8x8_DrawGlyph(u8x8, x, y, (uint8_t)c);
      x++;
      cnt++;
    }
  }
  return cnt;
}
#endif

static uint8_t u8x8_draw_string(u8x8_t *u8x8, uint8_t x, uint8_t y, const char *s) U8X8_NOINLINE;
static uint8_t u8x8_draw_string(u8x8_t *u8x8, uint8_t x, uint8_t y, const char *s)
{
  uint16_t e;
  uint8_t cnt = 0;
  u8x8_utf8_init(u8x8);
  for(;;)
  {
    e = u8x8->next_cb(u8x8, (uint8_t)*s);
    if ( e == 0x0ffff )
      break;
    s++;
    if ( e != 0x0fffe )
    {
      u8x8_DrawGlyph(u8x8, x, y, e);
      x++;
      cnt++;
    }
  }
  return cnt;
}


uint8_t u8x8_DrawString(u8x8_t *u8x8, uint8_t x, uint8_t y, const char *s)
{
  u8x8->next_cb = u8x8_ascii_next;
  return u8x8_draw_string(u8x8, x, y, s);
}

uint8_t u8x8_DrawUTF8(u8x8_t *u8x8, uint8_t x, uint8_t y, const char *s)
{
  u8x8->next_cb = u8x8_utf8_next;
  return u8x8_draw_string(u8x8, x, y, s);
}

uint8_t u8x8_GetUTF8Len(u8x8_t *u8x8, const char *s)
{
  uint16_t e;
  uint8_t cnt = 0;
  u8x8_utf8_init(u8x8);
  for(;;)
  {
    e = u8x8_utf8_next(u8x8, *s);
    if ( e == 0x0ffff )
      break;
    s++;
    if ( e != 0x0fffe )
      cnt++;
  }
  return cnt;
}


/*
void u8x8_Draw8x8UTF8(u8x8_t *u8x8, uint8_t x, uint8_t y, const char *s)
{
  uint16_t unicode;
  for(;;)
  {
    unicode = u8x8_get_encoding_from_utf8_string(&s);
    if ( unicode == 0 )
      break;
    if ( unicode <= 255 )
    {
      u8x8_Draw8x8Glyph(u8x8, x, y, (uint8_t)unicode);
      x++;
    }
  }
}
*/




