src/libvideo/video.c

   1 /* video emulation
   2  *
   3  * (C) 2018 by Andreas Eversberg <jolly@eversberg.eu>
   4  * All Rights Reserved
   5  *
   6  * This program is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <stdio.h>
  21 #include <stdint.h>
  22 #include "video.h"
  23 #include "../libcpu/m68kcpu.h"
  24
  25 //#define DEBUG_COPPERLIST
  26
  27 static void planar2chunky(uint8_t *rgb, uint8_t *bitplanes[], uint16_t palette[], int planes, int width, int y_start, int y_end)
  28 {
  29         int x, y, p, b, i;
  30         uint8_t word[planes], chunk;
  31         uint16_t rgb4;
  32
  33         /* we start memory read from the following calulated bitplane offset: */
  34         i = y_start * (width / 8);
  35         rgb += y_start * width * 3;
  36         for (y = y_start; y < y_end; y++) {
  37                 for (x = 0; x < width; x += 8) {
  38                         for (p = 0; p < planes; p++)
  39                                 word[p] = bitplanes[p][i];
  40                         for (b = 0; b < 8; b++) {
  41                                 chunk = (word[planes - 1] >> 7);
  42                                 word[planes - 1] <<= 1;
  43                                 for (p = planes - 2; p >= 0; p--) {
  44                                         chunk = (chunk << 1) | (word[p] >> 7);
  45                                         word[p] <<= 1;
  46                                 }
  47                                 rgb4 = palette[chunk];
  48                                 *rgb++ = (rgb4 >> 4) & 0xf0;
  49                                 *rgb++ = rgb4 & 0xf0;
  50                                 *rgb++ = rgb4 << 4;
  51                         }
  52                         i++;
  53                 }
  54         }
  55 }
  56
  57 static void planar2chunky2(uint8_t *rgb1, uint8_t *bitplanes[], uint16_t palette[], int planes, int width, int y_start, int y_end)
  58 {
  59         uint8_t *rgb2, red, green, blue;
  60         int x, y, p, b, i;
  61         uint8_t word[planes], chunk;
  62         uint16_t rgb4;
  63
  64         rgb2 = rgb1 + width * 6;
  65
  66         /* we start memory read from the following calulated bitplane offset: */
  67         i = y_start * (width / 8);
  68         rgb1 += 2 * y_start * width * 6;
  69         rgb2 += 2 * y_start * width * 6;
  70         for (y = y_start; y < y_end; y++) {
  71                 for (x = 0; x < width; x += 8) {
  72                         for (p = 0; p < planes; p++)
  73                                 word[p] = bitplanes[p][i];
  74                         for (b = 0; b < 8; b++) {
  75                                 chunk = (word[planes - 1] >> 7);
  76                                 word[planes - 1] <<= 1;
  77                                 for (p = planes - 2; p >= 0; p--) {
  78                                         chunk = (chunk << 1) | (word[p] >> 7);
  79                                         word[p] <<= 1;
  80                                 }
  81                                 rgb4 = palette[chunk];
  82                                 red = (rgb4 >> 4) & 0xf0;
  83                                 green = rgb4 & 0xf0;
  84                                 blue = rgb4 << 4;
  85                                 *rgb1++ = red;
  86                                 *rgb1++ = green;
  87                                 *rgb1++ = blue;
  88                                 *rgb1++ = red;
  89                                 *rgb1++ = green;
  90                                 *rgb1++ = blue;
  91                                 *rgb2++ = red;
  92                                 *rgb2++ = green;
  93                                 *rgb2++ = blue;
  94                                 *rgb2++ = red;
  95                                 *rgb2++ = green;
  96                                 *rgb2++ = blue;
  97                         }
  98                         i++;
  99                 }
 100                 rgb1 += width * 6;
 101                 rgb2 += width * 6;
 102         }
 103 }
 104
 105 #define COP1LCH         0x080
 106 #define COP1LCL         0x082
 107 #define COP2LCH         0x084
 108 #define COP2LCL         0x086
 109 #define BPL1PTH         0x0e0
 110 #define COLOR00         0x180
 111
 112 void emul_video(uint8_t *rgb, uint8_t *memory, uint16_t render_palette[], int width, int height, int diwstart, uint16_t *io, int start, int stop, int double_size)
 113 {
 114         uint32_t bitplane[8] = {0, 0, 0, 0, 0, 0, 0, 0};
 115         uint8_t *bitmem[8];
 116         uint16_t palette[16];
 117         uint32_t copperlist;
 118         uint16_t c1, c2;
 119         int row, last_row, line, last_line, from, to;
 120         int count;
 121         int i;
 122         int all_white;
 123
 124         /* special case where all palette entries are white. (unknown reason, maybe due to teleporter travel) */
 125         all_white = 1;
 126         for (i = 0; i < 16; i++) {
 127                 if (io[i * 2 + 0x180] != 0xfff)
 128                         all_white = 0;
 129         }
 130
 131         /* First set palette as specified in IO space.
 132          * This is set with last IRQ, so it is used after VBL.
 133          * Later the copper list causes them to be changed */
 134         for (i = 0; i < 16; i++) {
 135                 /* use palette if all value are white, else use the palette that is used during VBL-IRQ */
 136                 if (all_white)
 137                         palette[i] = io[i * 2 + 0x180];
 138                 else {
 139                         /* use palette that will be set during IRQ routine.
 140                          * we need to copy it here, because we don't call IRQ routine for every rendered frame,
 141                          * so the color registers are not set by IRQ routine for every frame.
 142                          */
 143                         palette[i] = render_palette[i];
 144                 }
 145         }
 146
 147         /* get copper list start pointer */
 148         copperlist = (io[COP1LCH] << 16) | io[COP1LCL];
 149         if (!copperlist) {
 150                 fprintf(stderr, "Copper list pointer not initialized, please fix!\n");
 151                 return;
 152         }
 153
 154 #ifdef DEBUG_COPPERLIST
 155         printf("Copper list reading from pointer: %06x\n", copperlist);
 156 #endif
 157
 158         /* parse copper list */
 159         count = 0;
 160         last_row = 0;
 161         last_line = 0;
 162         while (42) {
 163                 if (++count == 100) {
 164                         fprintf(stderr, "Copper list does not seem to terminate, please fix!\n");
 165                         return;
 166                 }
 167                 c1 = m68k_read_memory_16(copperlist);
 168                 c2 = m68k_read_memory_16(copperlist + 2);
 169 #ifdef DEBUG_COPPERLIST
 170                 printf("%06x: C1=%04x C2=%04x\n", copperlist, c1, c2);
 171 #endif
 172                 copperlist += 4;
 173                 if (c1 == 0x0088) {
 174                         copperlist = (io[COP1LCH] << 16) | io[COP1LCL];
 175 #ifdef DEBUG_COPPERLIST
 176                         printf("switching to 1st copperlist=%06x\n", copperlist);
 177 #endif
 178                         continue;
 179                 }
 180                 if (c1 == 0x008a) {
 181                         copperlist = (io[COP2LCH] << 16) | io[COP2LCL];
 182 #ifdef DEBUG_COPPERLIST
 183                         printf("switching to 2nd copperlist=%06x\n", copperlist);
 184 #endif
 185                         continue;
 186                 }
 187                 if (!(c1 & 1)) {
 188                         /* MOVE */
 189 #ifdef DEBUG_COPPERLIST
 190                         printf("MOVE 0xdff%03x = 0x%04x\n", c1, c2);
 191 #endif
 192                         /* get bitplane pointers */
 193                         if (c1 >= BPL1PTH && c1 <= BPL1PTH + 32) {
 194                                 if ((c1 & 2))
 195                                         bitplane[(c1 - BPL1PTH) / 4] = (bitplane[(c1 - BPL1PTH) / 4] & 0xffff0000) | c2;
 196                                 else
 197                                         bitplane[(c1 - BPL1PTH) / 4] = (bitplane[(c1 - BPL1PTH) / 4] & 0x0000ffff) | (c2 << 16);
 198                         }
 199                         /* get color registers */
 200                         if (c1 >= COLOR00 && c1 <= COLOR00 + 32) {
 201                                 palette[(c1 - COLOR00) / 2] = c2;
 202                         }
 203                 } else {
 204                         if ((c2 & 1)) {
 205                                 fprintf(stderr, "We suppport no SKIP command in copper list, please fix!\n");
 206                                 continue;
 207                         }
 208                         /* WAIT */
 209                         /* get new raster position.
 210                          * if the value is lower or equal, we add 256 lines
 211                          * we ignore column, since it is not relevant for this game.
 212                          */
 213                         row = (c1 >> 8) & ((c2 >> 8) | 0x80);
 214                         if (row < (last_row & 0xff))
 215                                 row |= 0x100;
 216 #ifdef DEBUG_COPPERLIST
 217                         printf("WAIT row = 0x%02x & 0x%02x = %d\n", c1 >> 8, (c2 >> 8) | 0x80, row);
 218 #endif
 219                         last_row = row;
 220                         /* line relative to display window start */
 221                         line = row - diwstart;
 222                         /* continue: before display window start */
 223                         if (line <= last_line)
 224                                 continue;
 225                         /* render up to height */
 226                         if (line >= height)
 227                                 line = height;
 228                         /* check if bitplane pointers are set */
 229 #ifdef DEBUG_COPPERLIST
 230                         printf("Bitplanes:");
 231 #endif
 232                         for (i = 0; i < 4; i++) {
 233 #ifdef DEBUG_COPPERLIST
 234                                 printf(" %06x", bitplane[i]);
 235 #endif
 236                                 if (bitplane[i] == 0 || bitplane[i] + width * height / 8 >= 0x80000) {
 237                                         printf("\n");
 238                                         fprintf(stderr, "Bitplane %d in copper list not set or out of range, please fix!\n", i);
 239                                         return;
 240                                 }
 241                                 bitmem[i] = memory + bitplane[i];
 242                         }
 243 #ifdef DEBUG_COPPERLIST
 244                         printf("\n");
 245 #endif
 246                         /* render portion before WAIT line */
 247 #ifdef DEBUG_COPPERLIST
 248                         printf("Render from line %d to line %d\n", last_line, line - 1);
 249 #endif
 250 #ifdef DEBUG_COPPERLIST
 251                         printf("Palette:");
 252                         for (i = 0; i < 16; i++) {
 253                                 printf(" %03x", palette[i] & 0xfff);
 254                         }
 255                         printf("\n");
 256 #endif
 257
 258                         from = last_line;
 259                         to = line;
 260                         if (start > from)
 261                                 from = start;
 262                         if (stop < to)
 263                                 to = stop;
 264                         if (to > from) {
 265                                 if (double_size)
 266                                         planar2chunky2(rgb, bitmem, palette, 4, width, from, to);
 267                                 else
 268                                         planar2chunky(rgb, bitmem, palette, 4, width, from, to);
 269                         }
 270                         /* done if we rendered up to height */
 271                         if (line == height)
 272                                 break;
 273                         /* remeber for next wait command */
 274                         last_row = row;
 275                         last_line = line;
 276                 }
 277         }
 278
 279 }