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gb-emu: initial commit

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Add a mostly non-functional Gameboy CPU and the skeleton
of a Gameboy assembler intended for unit tests.
This commit is contained in:
Max Regan
2016-12-18 23:43:41 -08:00
commit 6e2f4096a2
38 changed files with 4424 additions and 0 deletions
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src/video.h Normal file
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#ifndef VIDEO_H
#define VIDEO_H
#define CYCLES_PER_LINE 167
#define LCD_Y_MAX 153
#include <stdint.h>
struct gb_video {
/* Comments ripped http://fms.komkon.org/GameBoy/Tech/Software.html */
/* FF40 -- LCDCONT [RW] LCD Control | when set to 1 | when set to 0 */
/* Bit7 LCD operation | ON | OFF */
/* Bit6 Window Tile Table address | 9C00-9FFF | 9800-9BFF */
/* Bit5 Window display | ON | OFF */
/* Bit4 Tile Pattern Table address | 8000-8FFF | 8800-97FF */
/* Bit3 Background Tile Table address | 9C00-9FFF | 9800-9BFF */
/* Bit2 Sprite size | 8x16 | 8x8 */
/* Bit1 Color #0 transparency in the window | SOLID | TRANSPARENT */
/* Bit0 Background display | ON | OFF */
uint8_t lcdcont;
/* FF41 -- LCDSTAT [RW] LCD Status | when set to 1 | when set to 0 */
/* Bit6 Interrupt on scanline coincidence | ON | OFF */
/* Bit5 Interrupt on controller mode 10 | ON | OFF */
/* Bit4 Interrupt on controller mode 01 | ON | OFF */
/* Bit3 Interrupt on controller mode 00 | ON | OFF */
/* Bit2 Scanline coincidence flag | COINCIDENCE | NO COINCIDENCE */
/* Bit1-0 LCD Controller mode: */
/* 00 - Horizontal blanking impulse [VRAM 8000-9FFF can be accessed by CPU] */
/* 01 - Vertical blanking impulse [VRAM 8000-9FFF can be accessed by CPU] */
/* 10 - OAM FE00-FE90 is accessed by LCD controller */
/* 11 - Both OAM FE00-FE90 and VRAM 8000-9FFF are accessed by LCD controller */
uint8_t lcdstat;
/* FF42 -- SCROLLY [RW] Background Vertical Scrolling */
uint8_t scrolly;
/* FF43 -- SCROLLX [RW] Background Horizontal Scrolling */
uint8_t scrollx;
/* FF44 -- CURLINE [RW] Current Scanline */
/* This register contains the number of a screen line currently being */
/* scanned. It can take values 0-153 where 144-153 indicate the vertical */
/* blanking period. Writing into this register resets it. */
uint8_t curline;
/* FF45 -- CMPLINE [RW] Scanline Comparison */
/* When contents of CURLINE are equal to contents of CMPLINE, scanline */
/* coincidence flag is set in the LCD status register and an interrupt */
/* may occur. */
uint8_t cmpline;
/* FF47 -- BGRDPAL [W] Background Palette */
/* Bit7-6 Palette for color #3 | */
/* Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 */
/* Bit3-2 Palette for color #1 | lightest darkest */
/* Bit1-0 Palette for color #0 | */
uint8_t bgrdpal;
/* FF48 -- OBJ0PAL [W] Sprite Palette #0 */
/* Bit7-6 Palette for color #3 | */
/* Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 */
/* Bit3-2 Palette for color #1 | lightest darkest */
/* Bit1-0 Palette for color #0 | */
uint8_t obj0pal;
/* FF49 -- OBJ1PAL [W] Sprite Palette #1 */
/* Bit7-6 Palette for color #3 | */
/* Bit5-4 Palette for color #2 | 00 ------- 01 ------- 10 -------> 11 */
/* Bit3-2 Palette for color #1 | lightest darkest */
/* Bit1-0 Palette for color #0 | */
uint8_t obj1pal;
/* FF4A -- WNDPOSY [RW] Window Y Position */
/* WNDPOSY may assume values 0-143. It determines the vertical position */
/* of the left upper corner of a window on the screen. */
uint8_t wndposy;
/* FF4B -- WNDPOSX [RW] Window X Position */
/* WNDPOSX may assume values 7-166. It determines the horizontal position */
/* of the left upper corner of a window on the screen. The real position */
/* is WNDPOSX-7. */
uint8_t wndposx;
/******************************/
/***** Internal stuff *********/
/******************************/
int line_counter;
};
void gb_video_init(struct gb_video *video);
void gb_video_cycle(struct gb_video *video);
uint8_t gb_video_mem_read(struct gb_video *video, uint16_t addr);
void gb_video_mem_write(struct gb_video *video, uint16_t addr, uint8_t val);
#endif