Max Regan
6e2f4096a2
Add a mostly non-functional Gameboy CPU and the skeleton of a Gameboy assembler intended for unit tests.
101 lines
4.1 KiB
C
101 lines
4.1 KiB
C
#ifndef VIDEO_H
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#define VIDEO_H
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#define CYCLES_PER_LINE 167
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#define LCD_Y_MAX 153
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#include <stdint.h>
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struct gb_video {
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/* Comments ripped http://fms.komkon.org/GameBoy/Tech/Software.html */
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/* FF40 -- LCDCONT [RW] LCD Control | when set to 1 | when set to 0 */
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/* Bit7 LCD operation | ON | OFF */
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/* Bit6 Window Tile Table address | 9C00-9FFF | 9800-9BFF */
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/* Bit5 Window display | ON | OFF */
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/* Bit4 Tile Pattern Table address | 8000-8FFF | 8800-97FF */
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/* Bit3 Background Tile Table address | 9C00-9FFF | 9800-9BFF */
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/* Bit2 Sprite size | 8x16 | 8x8 */
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/* Bit1 Color #0 transparency in the window | SOLID | TRANSPARENT */
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/* Bit0 Background display | ON | OFF */
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uint8_t lcdcont;
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/* FF41 -- LCDSTAT [RW] LCD Status | when set to 1 | when set to 0 */
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/* Bit6 Interrupt on scanline coincidence | ON | OFF */
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/* Bit5 Interrupt on controller mode 10 | ON | OFF */
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/* Bit4 Interrupt on controller mode 01 | ON | OFF */
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/* Bit3 Interrupt on controller mode 00 | ON | OFF */
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/* Bit2 Scanline coincidence flag | COINCIDENCE | NO COINCIDENCE */
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/* Bit1-0 LCD Controller mode: */
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/* 00 - Horizontal blanking impulse [VRAM 8000-9FFF can be accessed by CPU] */
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/* 01 - Vertical blanking impulse [VRAM 8000-9FFF can be accessed by CPU] */
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/* 10 - OAM FE00-FE90 is accessed by LCD controller */
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/* 11 - Both OAM FE00-FE90 and VRAM 8000-9FFF are accessed by LCD controller */
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uint8_t lcdstat;
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/* FF42 -- SCROLLY [RW] Background Vertical Scrolling */
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uint8_t scrolly;
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/* FF43 -- SCROLLX [RW] Background Horizontal Scrolling */
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uint8_t scrollx;
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/* FF44 -- CURLINE [RW] Current Scanline */
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/* This register contains the number of a screen line currently being */
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/* scanned. It can take values 0-153 where 144-153 indicate the vertical */
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/* blanking period. Writing into this register resets it. */
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uint8_t curline;
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/* FF45 -- CMPLINE [RW] Scanline Comparison */
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/* When contents of CURLINE are equal to contents of CMPLINE, scanline */
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/* coincidence flag is set in the LCD status register and an interrupt */
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/* may occur. */
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uint8_t cmpline;
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/* FF47 -- BGRDPAL [W] Background Palette */
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/* Bit7-6 Palette for color #3 | */
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/* Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 */
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/* Bit3-2 Palette for color #1 | lightest darkest */
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/* Bit1-0 Palette for color #0 | */
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uint8_t bgrdpal;
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/* FF48 -- OBJ0PAL [W] Sprite Palette #0 */
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/* Bit7-6 Palette for color #3 | */
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/* Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 */
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/* Bit3-2 Palette for color #1 | lightest darkest */
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/* Bit1-0 Palette for color #0 | */
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uint8_t obj0pal;
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/* FF49 -- OBJ1PAL [W] Sprite Palette #1 */
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/* Bit7-6 Palette for color #3 | */
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/* Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 */
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/* Bit3-2 Palette for color #1 | lightest darkest */
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/* Bit1-0 Palette for color #0 | */
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uint8_t obj1pal;
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/* FF4A -- WNDPOSY [RW] Window Y Position */
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/* WNDPOSY may assume values 0-143. It determines the vertical position */
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/* of the left upper corner of a window on the screen. */
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uint8_t wndposy;
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/* FF4B -- WNDPOSX [RW] Window X Position */
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/* WNDPOSX may assume values 7-166. It determines the horizontal position */
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/* of the left upper corner of a window on the screen. The real position */
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/* is WNDPOSX-7. */
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uint8_t wndposx;
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/******************************/
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/***** Internal stuff *********/
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/******************************/
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int line_counter;
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};
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void gb_video_init(struct gb_video *video);
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void gb_video_cycle(struct gb_video *video);
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uint8_t gb_video_mem_read(struct gb_video *video, uint16_t addr);
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void gb_video_mem_write(struct gb_video *video, uint16_t addr, uint8_t val);
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#endif
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