/*------------------------------------------------------------------------------  -----------------
  Copyright J.Hubert 2015

  This file is part of demOS

  demOS is free software: you can redistribute it and/or modify it under the terms of 
  the GNU Lesser General Public License as published by the Free Software Foundation, 
  either version 3 of the License, or (at your option) any later version.

  demOS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY ;
  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
  See the GNU Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License along with demOS.  
  If not, see <http://www.gnu.org/licenses/>.
------------------------------------------------------------------------------------------------- */

#define COLORS_C

#include "DEMOSDK\COLORS.H"

u8 COLST24b[16] = 
{
    0x0,    /* 0 */
    0x2,    /* 1 */
    0x4,    /* 2 */
    0x6,    /* 3 */
    0x8,    /* 4 */
    0xA,    /* 5 */
    0xC,    /* 6 */
    0xE,    /* 7 */
    0x1,    /* 8 */
    0x3,    /* 9 */
    0x5,    /* A */
    0x7,    /* B */
    0x9,    /* C */
    0xB,    /* D */
    0xD,    /* E */
    0xF     /* F */
};

u8 COL4b2ST[17] =
{
    0x0,    /* 0 */
    0x8,    /* 1 */
    0x1,    /* 2 */
    0x9,    /* 3 */
    0x2,    /* 4 */
    0xA,    /* 5 */
    0x3,    /* 6 */
    0xB,    /* 7 */
    0x4,    /* 8 */
    0xC,    /* 9 */
    0x5,    /* A */
    0xD,    /* B */
    0x6,    /* C */
    0xE,    /* D */
    0x7,    /* E */
    0xF,    /* F */
    0xF     /* Sature */
};


u16* COLcomputeGradient (u16* _startColors, u16* _endcolors, u16 _nbColors, s16 _nbSteps, u16* _destColors)
{
    s16 s;


    _nbSteps--;

    for (s = 0 ; s <= _nbSteps ; s++)
    {
        u16  n;
        u16* scp = _startColors;
        u16* ecp = _endcolors;

        for (n = 0 ; n < _nbColors ; n++)
        {
            u16 sc = *scp++;
            u16 ec = *ecp++;

            s16 rs = COLST24b[(sc & 0xF00) >> 8];
            s16 gs = COLST24b[(sc & 0xF0 ) >> 4];
            s16 bs = COLST24b[(sc & 0xF  )     ];

            s16 re = COLST24b[(ec & 0xF00) >> 8];
            s16 ge = COLST24b[(ec & 0xF0 ) >> 4];
            s16 be = COLST24b[(ec & 0xF  )     ];

            s16 rd = ( ((re - rs) * s) / _nbSteps ) + rs; 
            s16 gd = ( ((ge - gs) * s) / _nbSteps ) + gs;
            s16 bd = ( ((be - bs) * s) / _nbSteps ) + bs;

            *_destColors++ = (COL4b2ST[rd] << 8) | (COL4b2ST[gd] << 4) | COL4b2ST[bd];
        }
    }

    return _destColors;
}


u16 COLcomputeGradientEx (u16* _startColors, u16* _endcolors, u16 _nbColors, s16 _nbSteps, u16* _destColors1, u16* _destColors2)
{
    u16* destColors1buf = _destColors1;
    s16 s;


    _nbSteps--;

    for (s = 0 ; s <= _nbSteps ; s++)
    {
        u16  n;
        u16* scp = _startColors;
        u16* ecp = _endcolors;

        for (n = 0 ; n < _nbColors ; n++)
        {
            u16 sc = *scp++;
            u16 ec = *ecp++;

            s16 rs = (COLST24b[(sc & 0xF00) >> 8] << 1) | ((sc & 0x4000) != 0);
            s16 gs = (COLST24b[(sc & 0xF0 ) >> 4] << 1) | ((sc & 0x2000) != 0);
            s16 bs = (COLST24b[(sc & 0xF  )     ] << 1) | ((sc & 0x1000) != 0);

            s16 re = (COLST24b[(ec & 0xF00) >> 8] << 1) | ((sc & 0x4000) != 0);
            s16 ge = (COLST24b[(ec & 0xF0 ) >> 4] << 1) | ((sc & 0x2000) != 0);
            s16 be = (COLST24b[(ec & 0xF  )     ] << 1) | ((sc & 0x1000) != 0);

            s16 rd = ( ((re - rs) * s) / _nbSteps ) + rs;
            s16 gd = ( ((ge - gs) * s) / _nbSteps ) + gs;
            s16 bd = ( ((be - bs) * s) / _nbSteps ) + bs;

            u8  lowbits = (( rd & 1 ) << 2) | (( gd & 1 ) << 1) | ( bd & 1 );

            s16 rd2 = rd >> 1;
            s16 gd2 = gd >> 1;
            s16 bd2 = bd >> 1;

            rd = rd2;
            gd = gd2;
            bd = bd2;

            switch ( lowbits )
            {
            case 1:                 bd2++;  break;
            case 2:         gd2++;          break;
            case 3:         gd++;   bd2++;  break;
            case 4: rd2++;                  break;
            case 5: rd++;           bd2++;  break;
            case 6: rd2++;  gd++;           break;
            case 7: rd++;   gd2++;  bd++;   break;  
            }

            *_destColors1++ = (COL4b2ST[rd] << 8) | (COL4b2ST[gd] << 4) | COL4b2ST[bd];
            *_destColors2++ = (COL4b2ST[rd2] << 8) | (COL4b2ST[gd2] << 4) | COL4b2ST[bd2];
        }
    }

    return ((u8*)_destColors1 - (u8*)destColors1buf) >> 1;  /* pointer arithmetics generate ldiv in PureC if sizeof != 1 ...*/
}