filter.c

   1 /*
   2  * filter.c
   3  * Copyright (C) 2003 Florian Schulze <crow@icculus.org>
   4  *
   5  * This file is part of Jump'n'Bump.
   6  *
   7  * Jump'n'Bump is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * Jump'n'Bump is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 /*
  23  The following scaling filter is called advancedmame2x.
  24  The implementation found here was possible because of the great ideas of
  25  Lucas Pope.
  26  */
  27
  28 typedef unsigned char byte;
  29 static int scale2x_inited = 0;
  30 static byte lookup_map[4*16];
  31
  32 void init_scale2x(void)
  33 {
  34         int i;
  35
  36         if (scale2x_inited)
  37                 return;
  38
  39         //-------------------------------------------------------------------------
  40         // scale2x takes the following source:
  41         // A B C
  42         // D E F
  43         // G H I
  44         //
  45         // and doubles the size of E to produce:
  46         // E0 E1
  47         // E2 E3
  48         //
  49         //  E0 = D == B && B != F && D != H ? D : E;
  50         //  E1 = B == F && B != D && F != H ? F : E;
  51         //  E2 = D == H && D != B && H != F ? D : E;
  52         //  E3 = H == F && D != H && B != F ? F : E;
  53         //
  54         // to make this comparison regimen faster, we encode source color
  55         // equivalency into a single byte with the getCode() macro
  56         //
  57         // #define getCode(b,f,h,d) ( (b == f)<<0 | (f == h)<<1 | (h == d)<<2 | (d == b)<<3 )
  58
  59         // encode the scale2x conditionals into a lookup code
  60         for (i=0; i<16; i++) {
  61                 //  E0 = D == B && B != F && D != H ? D : E; // 10-0 => 1000 or 1010 => 8 or A
  62                 lookup_map[0*16+i] = (i == 0x8 || i == 0xA) ? 0 : 1;
  63                 //  E1 = B == F && B != D && F != H ? F : E; // 0-01 => 0101 or 0001 => 5 or 1
  64                 lookup_map[1*16+i] = (i == 0x5 || i == 0x1) ? 2 : 1;
  65                 //  E2 = D == H && D != B && H != F ? D : E; // 010- => 0101 or 0100 => 5 or 4
  66                 lookup_map[2*16+i] = (i == 0x4 || i == 0x5) ? 0 : 1;
  67                 //  E3 = H == F && D != H && B != F ? F : E; // -010 => 1010 or 0010 => A or 2
  68                 lookup_map[3*16+i] = (i == 0xA || i == 0x2) ? 2 : 1;
  69         }
  70 }
  71
  72 void do_scale2x(unsigned char *src,
  73                 int src_width,
  74                 int src_height,
  75                 unsigned char *dst)
  76 {
  77         int x;
  78         int y;
  79         int dst_width = src_width * 2;
  80         int dst_height = src_height * 2;
  81         int code;
  82         byte rowColors[3];
  83         byte *e0;
  84         byte *e1;
  85         byte *e2;
  86         byte *e3;
  87
  88         if (!scale2x_inited)
  89                 init_scale2x();
  90
  91         // special top case - b is always unknown
  92         {
  93                 byte *d;
  94                 byte *e;
  95                 byte *f;
  96                 byte *h;
  97
  98                 e0 = &dst[0];
  99                 e1 = &dst[1];
 100                 e2 = &dst[dst_width];
 101                 e3 = &dst[dst_width + 1];
 102                 e = &src[0];
 103                 f = &src[1];
 104                 h = &src[src_width];
 105
 106                 // special left case - d is unknown
 107                 rowColors[0] = *e;
 108                 rowColors[1] = *e;
 109                 rowColors[2] = *f;
 110                 code = ( (*f == *h)<<1 );
 111                 *e0 = rowColors[lookup_map[0*16+code]];
 112                 *e1 = rowColors[lookup_map[1*16+code]];
 113                 *e2 = rowColors[lookup_map[2*16+code]];
 114                 *e3 = rowColors[lookup_map[3*16+code]];
 115                 e++; f++; h++;
 116                 d = &src[src_width]; // (src_width - 1) + 1
 117                 e0+=2; e1+=2; e2+=2; e3+=2;
 118
 119                 // normal case
 120                 for (x=1; x<(src_width-1); x++) {
 121                         rowColors[0] = *d;
 122                         rowColors[1] = *e;
 123                         rowColors[2] = *f;
 124                         code = ( (*f == *h)<<1 | (*h == *d)<<2 );
 125                         *e0 = rowColors[lookup_map[0*16+code]];
 126                         *e1 = rowColors[lookup_map[1*16+code]];
 127                         *e2 = rowColors[lookup_map[2*16+code]];
 128                         *e3 = rowColors[lookup_map[3*16+code]];
 129                         d++; e++; f++; h++;
 130                         e0+=2; e1+=2; e2+=2; e3+=2;
 131                 }
 132
 133                 // special right case - f is unknown
 134                 rowColors[0] = *d;
 135                 rowColors[1] = *e;
 136                 rowColors[2] = *e;
 137                 code = ( (*h == *d)<<2 );
 138                 *e0 = rowColors[lookup_map[0*16+code]];
 139                 *e1 = rowColors[lookup_map[1*16+code]];
 140                 *e2 = rowColors[lookup_map[2*16+code]];
 141                 *e3 = rowColors[lookup_map[3*16+code]];
 142         }
 143
 144         // top and bottom always known
 145         for (y=1; y<(src_height-1); y++) {
 146                 byte *b;
 147                 byte *d;
 148                 byte *e;
 149                 byte *f;
 150                 byte *h;
 151
 152                 e0 = &dst[y*dst_width*2];
 153                 e1 = &dst[y*dst_width*2 + 1];
 154                 e2 = &dst[y*dst_width*2 + dst_width];
 155                 e3 = &dst[y*dst_width*2 + dst_width + 1];
 156                 b = &src[y * src_width - src_width];
 157                 e = &src[y * src_width];
 158                 f = &src[y * src_width + 1];
 159                 h = &src[y * src_width + src_width];
 160
 161                 // special left case - d is unknown
 162                 rowColors[0] = *e;
 163                 rowColors[1] = *e;
 164                 rowColors[2] = *f;
 165                 code = ( (*b == *f)<<0 | (*f == *h)<<1 );
 166                 *e0 = rowColors[lookup_map[0*16+code]];
 167                 *e1 = rowColors[lookup_map[1*16+code]];
 168                 *e2 = rowColors[lookup_map[2*16+code]];
 169                 *e3 = rowColors[lookup_map[3*16+code]];
 170                 b++; e++; f++; h++;
 171                 d = &src[y * src_width]; // (y * src_width - 1) + 1
 172                 e0+=2; e1+=2; e2+=2; e3+=2;
 173
 174                 // normal case
 175                 for (x=1; x<(src_width-1); x++) {
 176                         rowColors[0] = *d;
 177                         rowColors[1] = *e;
 178                         rowColors[2] = *f;
 179                         code = ( (*b == *f)<<0 | (*f == *h)<<1 | (*h == *d)<<2 | (*d == *b)<<3 );
 180                         *e0 = rowColors[lookup_map[0*16+code]];
 181                         *e1 = rowColors[lookup_map[1*16+code]];
 182                         *e2 = rowColors[lookup_map[2*16+code]];
 183                         *e3 = rowColors[lookup_map[3*16+code]];
 184                         b++; d++; e++; f++; h++;
 185                         e0+=2; e1+=2; e2+=2; e3+=2;
 186                 }
 187
 188                 // special right case - f is unknown
 189                 rowColors[0] = *d;
 190                 rowColors[1] = *e;
 191                 rowColors[2] = *e;
 192                 code = ( (*h == *d)<<2 | (*d == *b)<<3 );
 193                 *e0 = rowColors[lookup_map[0*16+code]];
 194                 *e1 = rowColors[lookup_map[1*16+code]];
 195                 *e2 = rowColors[lookup_map[2*16+code]];
 196                 *e3 = rowColors[lookup_map[3*16+code]];
 197         }
 198
 199         // special bottom case - h is always unknown
 200         {
 201                 byte *b;
 202                 byte *d;
 203                 byte *e;
 204                 byte *f;
 205
 206                 e0 = &dst[y*dst_width*2];
 207                 e1 = &dst[y*dst_width*2 + 1];
 208                 e2 = &dst[y*dst_width*2 + dst_width];
 209                 e3 = &dst[y*dst_width*2 + dst_width + 1];
 210                 b = &src[y * src_width - src_width];
 211                 e = &src[y * src_width];
 212                 f = &src[y * src_width + 1];
 213
 214                 // special left case - d is unknown
 215                 rowColors[0] = *e;
 216                 rowColors[1] = *e;
 217                 rowColors[2] = *f;
 218                 code = ( (*b == *f)<<0 );
 219                 *e0 = rowColors[lookup_map[0*16+code]];
 220                 *e1 = rowColors[lookup_map[1*16+code]];
 221                 *e2 = rowColors[lookup_map[2*16+code]];
 222                 *e3 = rowColors[lookup_map[3*16+code]];
 223                 b++; e++; f++;
 224                 d = &src[y * src_width]; // (y * src_width - 1) + 1
 225                 e0+=2; e1+=2; e2+=2; e3+=2;
 226
 227                 // normal case
 228                 for (x=1; x<(src_width-1); x++) {
 229                         rowColors[0] = *d;
 230                         rowColors[1] = *e;
 231                         rowColors[2] = *f;
 232                         code = ( (*b == *f)<<0 | (*d == *b)<<3 );
 233                         *e0 = rowColors[lookup_map[0*16+code]];
 234                         *e1 = rowColors[lookup_map[1*16+code]];
 235                         *e2 = rowColors[lookup_map[2*16+code]];
 236                         *e3 = rowColors[lookup_map[3*16+code]];
 237                         b++; d++; e++; f++;
 238                         e0+=2; e1+=2; e2+=2; e3+=2;
 239                 }
 240
 241                 // special right case - f is unknown
 242                 rowColors[0] = *d;
 243                 rowColors[1] = *e;
 244                 rowColors[2] = *e;
 245                 code = ( (*d == *b)<<3 );
 246                 *e0 = rowColors[lookup_map[0*16+code]];
 247                 *e1 = rowColors[lookup_map[1*16+code]];
 248                 *e2 = rowColors[lookup_map[2*16+code]];
 249                 *e3 = rowColors[lookup_map[3*16+code]];
 250         }
 251 }