From 04bfc89816eb35b071ec03453723be8750a42b14 Mon Sep 17 00:00:00 2001
From: Lior Halphon <LIJI32@gmail.com>
Date: Fri, 23 Mar 2018 19:07:14 +0300
Subject: [PATCH] Cycle accurate OAM search mode
---
Core/display.c | 55 ++++++++++++++++++++------------------------------
Core/gb.h | 1 +
2 files changed, 23 insertions(+), 33 deletions(-)
diff --git a/Core/display.c b/Core/display.c
index b06329e9..ee31a987 100755
--- a/Core/display.c
+++ b/Core/display.c
@@ -289,37 +289,22 @@ void GB_lcd_off(GB_gameboy_t *gb)
gb->ly_for_comparison = 0;
}
-static void search_oam(GB_gameboy_t *gb)
+static void add_object_from_index(GB_gameboy_t *gb, unsigned index)
{
- /*
- We have very little means to test how the OAM search timing actually
- works so we currently implement it atomically.
+ if (gb->n_visible_objs == 10) return;
- This is enough for most cases except (All are TODOs):
- - The OAM bug on the DMG (Not emulated at all)
- - Changing object height via LCDC during mode 2
- - What about changing during mode 3?
- - Enabling and disabling sprites during mode 2
- - Does this flag actually do anything in mode 2? Or only during mode 3?
- */
-
/* This reverse sorts the visible objects by location and priority */
-
GB_object_t *objects = (GB_object_t *) &gb->oam;
bool height_16 = (gb->io_registers[GB_IO_LCDC] & 4) != 0;
- gb->n_visible_objs = 0;
- for (uint8_t i = 0; i < 40; i++) {
- signed y = objects[i].y - 16;
- if (y <= gb->current_line && y + (height_16? 16 : 8) > gb->current_line) {
- unsigned j = 0;
- for (; j < gb->n_visible_objs; j++) {
- if (objects[gb->visible_objs[j]].x <= objects[i].x) break;
- }
- memmove(gb->visible_objs + j + 1, gb->visible_objs + j, gb->n_visible_objs - j);
- gb->visible_objs[j] = i;
- gb->n_visible_objs++;
- if (gb->n_visible_objs == 10) return;
+ signed y = objects[index].y - 16;
+ if (y <= gb->current_line && y + (height_16? 16 : 8) > gb->current_line) {
+ unsigned j = 0;
+ for (; j < gb->n_visible_objs; j++) {
+ if (objects[gb->visible_objs[j]].x <= objects[index].x) break;
}
+ memmove(gb->visible_objs + j + 1, gb->visible_objs + j, gb->n_visible_objs - j);
+ gb->visible_objs[j] = index;
+ gb->n_visible_objs++;
}
}
@@ -407,7 +392,7 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
GB_STATE(gb, display, 6);
GB_STATE(gb, display, 7);
GB_STATE(gb, display, 8);
- GB_STATE(gb, display, 9);
+ // GB_STATE(gb, display, 9);
GB_STATE(gb, display, 10);
GB_STATE(gb, display, 11);
GB_STATE(gb, display, 12);
@@ -514,14 +499,18 @@ void GB_display_run(GB_gameboy_t *gb, uint8_t cycles)
gb->oam_write_blocked = true;
gb->ly_for_comparison = gb->current_line;
GB_STAT_update(gb);
- GB_SLEEP(gb, display, 8, MODE2_LENGTH - 4);
+ gb->n_visible_objs = 0;
- search_oam(gb);
- gb->vram_read_blocked = !gb->is_cgb;
- gb->vram_write_blocked = false;
- gb->oam_write_blocked = gb->is_cgb;
- GB_STAT_update(gb);
- GB_SLEEP(gb, display, 9, 4);
+ for (gb->oam_search_index = 0; gb->oam_search_index < 40; gb->oam_search_index++) {
+ add_object_from_index(gb, gb->oam_search_index);
+ GB_SLEEP(gb, display, 8, 2);
+ if (gb->oam_search_index == 37) {
+ gb->vram_read_blocked = !gb->is_cgb;
+ gb->vram_write_blocked = false;
+ gb->oam_write_blocked = gb->is_cgb;
+ GB_STAT_update(gb);
+ }
+ }
gb->io_registers[GB_IO_STAT] &= ~3;
gb->io_registers[GB_IO_STAT] |= 3;
diff --git a/Core/gb.h b/Core/gb.h
index 2e646e1e..3d0a9193 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -426,6 +426,7 @@ struct GB_gameboy_internal_s {
uint8_t visible_objs[10];
uint8_t n_visible_objs;
bool fetching_objects;
+ uint8_t oam_search_index;
);
/* Unsaved data. This includes all pointers, as well as everything that shouldn't be on a save state */