From 8153b765a2ef1708b1f9ecf93a21018271e2bd61 Mon Sep 17 00:00:00 2001 From: Lior Halphon Date: Sun, 12 Jun 2016 19:39:05 +0300 Subject: [PATCH] General cleanup. Minor fixes to LCD Controller accuracy. --- Core/debugger.c | 2 - Core/display.c | 118 ++++++++++++++++++++++++------------------------ Core/gb.h | 4 +- 3 files changed, 61 insertions(+), 63 deletions(-) diff --git a/Core/debugger.c b/Core/debugger.c index 62615189..d757086c 100644 --- a/Core/debugger.c +++ b/Core/debugger.c @@ -683,8 +683,6 @@ void debugger_ret_hook(GB_gameboy_t *gb) } } -/* The debugger interface is quite primitive. One letter commands with a single parameter maximum. - Only one breakpoint is allowed at a time. More features will be added later. */ void debugger_run(GB_gameboy_t *gb) { char *input = NULL; diff --git a/Core/display.c b/Core/display.c index 4daa502d..2f38afbb 100644 --- a/Core/display.c +++ b/Core/display.c @@ -240,6 +240,23 @@ void palette_changed(GB_gameboy_t *gb, bool background_palette, unsigned char in (background_palette? gb->background_palletes_rgb : gb->sprite_palletes_rgb)[index / 2] = gb->rgb_encode_callback(gb, r, g, b); } + +/* + Each line is 456 cycles, approximately: + Mode 2 - 80 cycles / OAM Transfer + Mode 3 - 172 cycles / Rendering + Mode 0 - 204 cycles / HBlank + + Mode 1 is VBlank + + Todo: Mode lengths are not constants, see http://blog.kevtris.org/blogfiles/Nitty%20Gritty%20Gameboy%20VRAM%20Timing.txt + */ + +#define MODE2_LENGTH 80 +#define MODE3_LENGTH 172 +#define MODE1_LENGTH 204 +#define LINE_LENGTH (MODE2_LENGTH + MODE3_LENGTH + MODE1_LENGTH) // = 456 + void display_run(GB_gameboy_t *gb) { /* @@ -248,42 +265,43 @@ void display_run(GB_gameboy_t *gb) See http://forums.nesdev.com/viewtopic.php?f=20&t=13727 */ - unsigned char last_mode = gb->io_registers[GB_IO_STAT] & 3; /* STAT interrupt is implemented based on this finding: http://board.byuu.org/phpbb3/viewtopic.php?p=25527#p25531 */ + unsigned char previous_stat_interrupt_line = gb->stat_interrupt_line; gb->stat_interrupt_line = false; + unsigned char last_mode = gb->io_registers[GB_IO_STAT] & 3; + gb->io_registers[GB_IO_STAT] &= ~3; + if (gb->display_cycles >= LCDC_PERIOD) { /* VBlank! */ gb->display_cycles -= LCDC_PERIOD; - gb->ly144_bug_oam = false; - gb->ly144_bug_hblank = false; display_vblank(gb); } if (!(gb->io_registers[GB_IO_LCDC] & 0x80)) { /* LCD is disabled, do nothing */ - gb->io_registers[GB_IO_STAT] &= ~3; + + /* Some games expect LY to be zero when the LCD is off. + Todo: Verify this behavior. + Keep in mind that this only affects the value being read from the Gameboy, not the actualy display state. + This also explains why the coincidence interrupt triggers when LYC = 0 and LY = 153. */ gb->io_registers[GB_IO_LY] = 0; return; } - gb->io_registers[GB_IO_STAT] &= ~3; - /* - Each line is 456 cycles, approximately: - Mode 2 - 80 cycles - Mode 3 - 172 cycles - Mode 0 - 204 cycles - - Todo: Mode lengths are not constants??? - */ + gb->io_registers[GB_IO_LY] = gb->display_cycles / LINE_LENGTH; - gb->io_registers[GB_IO_LY] = gb->display_cycles / 456; + /* Todo: This behavior is seen in BGB and it fixes some ROMs with delicate timing, such as Hitman's 8bit. + This should be verified to be correct on a real gameboy. */ + if (gb->io_registers[GB_IO_LY] == 153 && gb->display_cycles % LINE_LENGTH > 8) { + gb->io_registers[GB_IO_LY] = 0; + } gb->io_registers[GB_IO_STAT] &= ~4; if (gb->io_registers[GB_IO_LY] == gb->io_registers[GB_IO_LYC]) { @@ -294,13 +312,7 @@ void display_run(GB_gameboy_t *gb) } } - /* Todo: This behavior is seen in BGB and it fixes some ROMs with delicate timing, such as Hitman's 8bit. - This should be verified to be correct on a real gameboy. */ - if (gb->io_registers[GB_IO_LY] == 153 && gb->display_cycles % 456 > 8) { - gb->io_registers[GB_IO_LY] = 0; - } - - if (gb->display_cycles >= 456 * 144) { /* VBlank */ + if (gb->display_cycles >= LINE_LENGTH * 144) { /* VBlank */ gb->io_registers[GB_IO_STAT] |= 1; /* Set mode to 1 */ gb->effective_window_enabled = false; gb->effective_window_y = 0xFF; @@ -314,23 +326,9 @@ void display_run(GB_gameboy_t *gb) // LY = 144 interrupt bug if (gb->io_registers[GB_IO_LY] == 144) { - if (gb->display_cycles % 456 < 80) { // Mode 2 - if (gb->io_registers[GB_IO_STAT] & 0x20 && !gb->ly144_bug_oam) { /* User requests an interrupt on Mode 2 */ - gb->io_registers[GB_IO_IF] |= 2; - } - gb->ly144_bug_oam = true; - } - if (gb->display_cycles % 456 < 80 + 172) { /* Mode 3 */ - // Nothing to do - } - else { /* Mode 0 */ - if (gb->io_registers[GB_IO_STAT] & 8 && !gb->ly144_bug_hblank) { /* User requests an interrupt on Mode 0 */ - /* - Todo: Verify if this actually happens. - gb->io_registers[GB_IO_IF] |= 2; - */ - } - gb->ly144_bug_hblank = true; + /* User requests an interrupt on Mode 2 */ + if (gb->display_cycles % LINE_LENGTH < 92 && gb->io_registers[GB_IO_STAT] & 0x20) { // Mode 2 + gb->stat_interrupt_line = true; } } @@ -342,7 +340,7 @@ void display_run(GB_gameboy_t *gb) gb->effective_window_enabled = true; } - if (gb->display_cycles % 456 < 80) { /* Mode 2 */ + if (gb->display_cycles % LINE_LENGTH < MODE2_LENGTH) { /* Mode 2 */ gb->io_registers[GB_IO_STAT] |= 2; /* Set mode to 2 */ if (gb->io_registers[GB_IO_STAT] & 0x20) { /* User requests an interrupt on Mode 2 */ @@ -359,32 +357,34 @@ void display_run(GB_gameboy_t *gb) goto updateSTAT; } - signed short current_lcdc_x = ((gb->display_cycles % 456 - 80) & ~7) - (gb->effective_scx & 0x7); - for (;gb->previous_lcdc_x < current_lcdc_x; gb->previous_lcdc_x++) { - if (gb->previous_lcdc_x >= 160) { - continue; + if (gb->display_cycles % LINE_LENGTH < MODE2_LENGTH + MODE3_LENGTH) { /* Mode 3 */ + if (last_mode != 3) { + } - if (gb->previous_lcdc_x < 0) { - continue; + signed short current_lcdc_x = ((gb->display_cycles % LINE_LENGTH - MODE2_LENGTH) & ~7) - (gb->effective_scx & 0x7); + for (;gb->previous_lcdc_x < current_lcdc_x; gb->previous_lcdc_x++) { + if (gb->previous_lcdc_x >= 160) { + continue; + } + if (gb->previous_lcdc_x < 0) { + continue; + } + gb->screen[gb->io_registers[GB_IO_LY] * 160 + gb->previous_lcdc_x] = + get_pixel(gb, gb->previous_lcdc_x, gb->io_registers[GB_IO_LY]); } - gb->screen[gb->io_registers[GB_IO_LY] * 160 + gb->previous_lcdc_x] = - get_pixel(gb, gb->previous_lcdc_x, gb->io_registers[GB_IO_LY]); - } - - if (gb->display_cycles % 456 < 80 + 172) { /* Mode 3 */ gb->io_registers[GB_IO_STAT] |= 3; /* Set mode to 3 */ goto updateSTAT; } - /* if (gb->display_cycles % 456 < 80 + 172 + 204) */ { /* Mode 0*/ - if (gb->io_registers[GB_IO_STAT] & 8) { /* User requests an interrupt on Mode 0 */ - gb->stat_interrupt_line = true; - } - if (last_mode != 0) { - if (gb->hdma_on_hblank) { - gb->hdma_on = true; - gb->hdma_cycles = 0; - } + /* Mode 0*/ + if (gb->io_registers[GB_IO_STAT] & 8) { /* User requests an interrupt on Mode 0 */ + gb->stat_interrupt_line = true; + } + + if (last_mode != 0) { + if (gb->hdma_on_hblank) { + gb->hdma_on = true; + gb->hdma_cycles = 0; } } diff --git a/Core/gb.h b/Core/gb.h index e89cc59b..cf2fca78 100644 --- a/Core/gb.h +++ b/Core/gb.h @@ -261,8 +261,8 @@ typedef struct GB_gameboy_s { unsigned char sprite_palletes_data[0x40]; uint32_t background_palletes_rgb[0x20]; uint32_t sprite_palletes_rgb[0x20]; - bool ly144_bug_oam; - bool ly144_bug_hblank; + GB_PADDING(bool, ly144_bug_oam); + GB_PADDING(bool, ly144_bug_hblank); signed short previous_lcdc_x; unsigned char padding; bool effective_window_enabled;