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 "../libsdl/print.h"
  23 #include "video.h"
  24 #include "../libcpu/m68kcpu.h"
  25
  26 //#define DEBUG_COPPERLIST
  27
  28 static void planar2chunky(uint8_t *rgb, uint8_t *bitplanes[], uint16_t palette[], int planes, int width, int y_start, int y_end)
  29 {
  30         int x, y, p, b, i;
  31         uint8_t word[planes], chunk;
  32         uint16_t rgb4;
  33
  34         /* we start memory read from the following calulated bitplane offset: */
  35         i = y_start * (width / 8);
  36         rgb += y_start * width * 3;
  37         for (y = y_start; y < y_end; y++) {
  38                 for (x = 0; x < width; x += 8) {
  39                         for (p = 0; p < planes; p++)
  40                                 word[p] = bitplanes[p][i];
  41                         for (b = 0; b < 8; b++) {
  42                                 chunk = (word[planes - 1] >> 7);
  43                                 word[planes - 1] <<= 1;
  44                                 for (p = planes - 2; p >= 0; p--) {
  45                                         chunk = (chunk << 1) | (word[p] >> 7);
  46                                         word[p] <<= 1;
  47                                 }
  48                                 rgb4 = palette[chunk];
  49                                 *rgb++ = (rgb4 >> 4) & 0xf0;
  50                                 *rgb++ = rgb4 & 0xf0;
  51                                 *rgb++ = rgb4 << 4;
  52                         }
  53                         i++;
  54                 }
  55         }
  56 }
  57
  58 static void planar2chunky2(uint8_t *rgb1, uint8_t *bitplanes[], uint16_t palette[], int planes, int width, int y_start, int y_end)
  59 {
  60         uint8_t *rgb2, red, green, blue;
  61         int x, y, p, b, i;
  62         uint8_t word[planes], chunk;
  63         uint16_t rgb4;
  64
  65         rgb2 = rgb1 + width * 6;
  66
  67         /* we start memory read from the following calulated bitplane offset: */
  68         i = y_start * (width / 8);
  69         rgb1 += 2 * y_start * width * 6;
  70         rgb2 += 2 * y_start * width * 6;
  71         for (y = y_start; y < y_end; y++) {
  72                 for (x = 0; x < width; x += 8) {
  73                         for (p = 0; p < planes; p++)
  74                                 word[p] = bitplanes[p][i];
  75                         for (b = 0; b < 8; b++) {
  76                                 chunk = (word[planes - 1] >> 7);
  77                                 word[planes - 1] <<= 1;
  78                                 for (p = planes - 2; p >= 0; p--) {
  79                                         chunk = (chunk << 1) | (word[p] >> 7);
  80                                         word[p] <<= 1;
  81                                 }
  82                                 rgb4 = palette[chunk];
  83                                 red = (rgb4 >> 4) & 0xf0;
  84                                 green = rgb4 & 0xf0;
  85                                 blue = rgb4 << 4;
  86                                 *rgb1++ = red;
  87                                 *rgb1++ = green;
  88                                 *rgb1++ = blue;
  89                                 *rgb1++ = red;
  90                                 *rgb1++ = green;
  91                                 *rgb1++ = blue;
  92                                 *rgb2++ = red;
  93                                 *rgb2++ = green;
  94                                 *rgb2++ = blue;
  95                                 *rgb2++ = red;
  96                                 *rgb2++ = green;
  97                                 *rgb2++ = blue;
  98                         }
  99                         i++;
 100                 }
 101                 rgb1 += width * 6;
 102                 rgb2 += width * 6;
 103         }
 104 }
 105
 106 #define COP1LCH         0x080
 107 #define COP1LCL         0x082
 108 #define COP2LCH         0x084
 109 #define COP2LCL         0x086
 110 #define BPL1PTH         0x0e0
 111 #define COLOR00         0x180
 112
 113 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)
 114 {
 115         uint32_t bitplane[8] = {0, 0, 0, 0, 0, 0, 0, 0};
 116         uint8_t *bitmem[8];
 117         uint16_t palette[16];
 118         uint32_t copperlist;
 119         uint16_t c1, c2;
 120         int row, last_row, line, last_line, from, to;
 121         int count;
 122         int i;
 123         int all_white;
 124
 125         /* special case where all palette entries are white. (unknown reason, maybe due to teleporter travel) */
 126         all_white = 1;
 127         for (i = 0; i < 16; i++) {
 128                 if (io[i * 2 + 0x180] != 0xfff)
 129                         all_white = 0;
 130         }
 131
 132         /* First set palette as specified in IO space.
 133          * This is set with last IRQ, so it is used after VBL.
 134          * Later the copper list causes them to be changed */
 135         for (i = 0; i < 16; i++) {
 136                 /* use palette if all value are white, else use the palette that is used during VBL-IRQ */
 137                 if (all_white)
 138                         palette[i] = io[i * 2 + 0x180];
 139                 else {
 140                         /* use palette that will be set during IRQ routine.
 141                          * we need to copy it here, because we don't call IRQ routine for every rendered frame,
 142                          * so the color registers are not set by IRQ routine for every frame.
 143                          */
 144                         palette[i] = render_palette[i];
 145                 }
 146         }
 147
 148         /* get copper list start pointer */
 149         copperlist = (io[COP1LCH] << 16) | io[COP1LCL];
 150         if (!copperlist) {
 151                 print_error("Copper list pointer not initialized, please fix!\n");
 152                 return;
 153         }
 154
 155 #ifdef DEBUG_COPPERLIST
 156         printf("Copper list reading from pointer: %06x\n", copperlist);
 157 #endif
 158
 159         /* parse copper list */
 160         count = 0;
 161         last_row = 0;
 162         last_line = 0;
 163         while (42) {
 164                 if (++count == 100) {
 165                         print_error("Copper list does not seem to terminate, please fix!\n");
 166                         return;
 167                 }
 168                 c1 = m68k_read_memory_16(copperlist);
 169                 c2 = m68k_read_memory_16(copperlist + 2);
 170 #ifdef DEBUG_COPPERLIST
 171                 printf("%06x: C1=%04x C2=%04x\n", copperlist, c1, c2);
 172 #endif
 173                 copperlist += 4;
 174                 if (c1 == 0x0088) {
 175                         copperlist = (io[COP1LCH] << 16) | io[COP1LCL];
 176 #ifdef DEBUG_COPPERLIST
 177                         printf("switching to 1st copperlist=%06x\n", copperlist);
 178 #endif
 179                         continue;
 180                 }
 181                 if (c1 == 0x008a) {
 182                         copperlist = (io[COP2LCH] << 16) | io[COP2LCL];
 183 #ifdef DEBUG_COPPERLIST
 184                         printf("switching to 2nd copperlist=%06x\n", copperlist);
 185 #endif
 186                         continue;
 187                 }
 188                 if (!(c1 & 1)) {
 189                         /* MOVE */
 190 #ifdef DEBUG_COPPERLIST
 191                         printf("MOVE 0xdff%03x = 0x%04x\n", c1, c2);
 192 #endif
 193                         /* get bitplane pointers */
 194                         if (c1 >= BPL1PTH && c1 <= BPL1PTH + 32) {
 195                                 if ((c1 & 2))
 196                                         bitplane[(c1 - BPL1PTH) / 4] = (bitplane[(c1 - BPL1PTH) / 4] & 0xffff0000) | c2;
 197                                 else
 198                                         bitplane[(c1 - BPL1PTH) / 4] = (bitplane[(c1 - BPL1PTH) / 4] & 0x0000ffff) | (c2 << 16);
 199                         }
 200                         /* get color registers */
 201                         if (c1 >= COLOR00 && c1 <= COLOR00 + 32) {
 202                                 palette[(c1 - COLOR00) / 2] = c2;
 203                         }
 204                 } else {
 205                         if ((c2 & 1)) {
 206                                 print_error("We suppport no SKIP command in copper list, please fix!\n");
 207                                 continue;
 208                         }
 209                         /* WAIT */
 210                         /* get new raster position.
 211                          * if the value is lower or equal, we add 256 lines
 212                          * we ignore column, since it is not relevant for this game.
 213                          */
 214                         row = (c1 >> 8) & ((c2 >> 8) | 0x80);
 215                         if (row < (last_row & 0xff))
 216                                 row |= 0x100;
 217 #ifdef DEBUG_COPPERLIST
 218                         printf("WAIT row = 0x%02x & 0x%02x = %d\n", c1 >> 8, (c2 >> 8) | 0x80, row);
 219 #endif
 220                         last_row = row;
 221                         /* line relative to display window start */
 222                         line = row - diwstart;
 223                         /* continue: before display window start */
 224                         if (line <= last_line)
 225                                 continue;
 226                         /* render up to height */
 227                         if (line >= height)
 228                                 line = height;
 229                         /* check if bitplane pointers are set */
 230 #ifdef DEBUG_COPPERLIST
 231                         printf("Bitplanes:");
 232 #endif
 233                         for (i = 0; i < 4; i++) {
 234 #ifdef DEBUG_COPPERLIST
 235                                 printf(" %06x", bitplane[i]);
 236 #endif
 237                                 if (bitplane[i] == 0 || bitplane[i] + width * height / 8 >= 0x80000) {
 238 #ifdef DEBUG_COPPERLIST
 239                                         printf("\n");
 240 #endif
 241                                         print_error("Bitplane %d in copper list not set or out of range, please fix!\n", i);
 242                                         return;
 243                                 }
 244                                 bitmem[i] = memory + bitplane[i];
 245                         }
 246 #ifdef DEBUG_COPPERLIST
 247                         printf("\n");
 248 #endif
 249                         /* render portion before WAIT line */
 250 #ifdef DEBUG_COPPERLIST
 251                         printf("Render from line %d to line %d\n", last_line, line - 1);
 252 #endif
 253 #ifdef DEBUG_COPPERLIST
 254                         printf("Palette:");
 255                         for (i = 0; i < 16; i++) {
 256                                 printf(" %03x", palette[i] & 0xfff);
 257                         }
 258                         printf("\n");
 259 #endif
 260
 261                         from = last_line;
 262                         to = line;
 263                         if (start > from)
 264                                 from = start;
 265                         if (stop < to)
 266                                 to = stop;
 267                         if (to > from) {
 268                                 if (double_size)
 269                                         planar2chunky2(rgb, bitmem, palette, 4, width, from, to);
 270                                 else
 271                                         planar2chunky(rgb, bitmem, palette, 4, width, from, to);
 272                         }
 273                         /* done if we rendered up to height */
 274                         if (line == height)
 275                                 break;
 276                         /* remeber for next wait command */
 277                         last_row = row;
 278                         last_line = line;
 279                 }
 280         }
 281
 282 }