From 98eb21a9e2b106c6b927964e54b93061955cd6bc Mon Sep 17 00:00:00 2001
From: condret <condr3t@protonmail.com>
Date: Wed, 6 Nov 2024 04:41:04 +0100
Subject: [PATCH] Minor progress gb_ppu_render_continue

---
 include/gb.h |  5 ++++
 io/ppu.c     | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 84 insertions(+), 3 deletions(-)

diff --git a/include/gb.h b/include/gb.h
index 60bc6d6..a0f7eb5 100644
--- a/include/gb.h
+++ b/include/gb.h
@@ -5,6 +5,11 @@
 #include <r_arch.h>
 #include <r_esil.h>
 
+#define	WHITE		0x86c06c
+#define	LIGHT_GRAY	0xe0f8cf
+#define DARK_GRAY	0
+#define BLACK		0
+
 enum {
 	GB_TIMERS_DIV = 0,
 	GB_TIMERS_TIMA,
diff --git a/io/ppu.c b/io/ppu.c
index 6ff93e9..e33e765 100644
--- a/io/ppu.c
+++ b/io/ppu.c
@@ -144,10 +144,11 @@ static ut32 gb_ppu_oam_scan_continue (GB *gb, ut32 cycles) {
 	while (cycles && gb->ppu->ost.addr <= 0xa0) {
 		if (gb->ppu->ost.n_entries < 10) {
 			ut8 yx[2];
+			//this is probably inaccurate
 			r_io_fd_read_at (gb->io, gb->dma->oam_fd, (ut64)gb->ppu->ost.addr, yx, 2);
-			if ((yx[0] <= ly) && (ly < (yx[0] + height)) && yx[1]) {
+			if ((yx[0] <= ly) && (ly < (yx[0] + height))) {
 				gb->ppu->ost.data[gb->ppu->ost.n_entries] =
-					(gb->ppu->ost.addr << 16) | (yx[0] << 8) | yx[0];
+					(gb->ppu->ost.addr << 16) | (yx[0] << 8) | yx[1];
 				gb->ppu->ost.n_entries++;
 			}
 		}
@@ -196,7 +197,7 @@ static void read_obj_data (GBPPU *ppu, RIO *io, ut8 *tile, int oam_fd) {
 	}
 }
 
-static void gb_ppu_pixel_fifo_merge_opixels (PixelFifo *pxf, bool priority) {
+static void gb_ppu_pixel_fifo_merge_opixels (PixelFifo *pxf) {
 	ut32 pixels = pxf->data >> 32;
 	ut32 newpixels = 0;
 	ut32 i;
@@ -311,6 +312,9 @@ static void gb_pixel_fifo_fetch_continue (GB *gb) {
 			}
 			fifo->fetcher[1].fetched |= (fifo->obj & GB_FIFO_OAM_PALLET)?
 				0xcccccccc: 0x88888888;
+			if ((fifo->obj & 0xff) < 8) { //is this correct?
+				fifo->fetcher[1].fetched <<= ((8 - (fifo->obj & 0xff)) << 2);
+			}
 		}
 		break;
 	case 7:
@@ -321,6 +325,56 @@ static void gb_pixel_fifo_fetch_continue (GB *gb) {
 	fifo->fetcher[fetch_obj].state_ctr = (fifo->fetcher[fetch_obj].state_ctr + 1) & 0x7;
 }
 
+static bool check_objects (GBPPU *ppu) {
+	if (!ppu->fifo.x) {
+		return false;
+	}
+	ut32 i;
+	for (i = 0; i < ppu->ost.n_entries; i++) {
+		const ut8 x = ppu->ost.data[i] & 0xff;
+		//x cannot be 0, because oam entries with x = 0 don't end in this array
+		//because of this setting x to 0 can be used to invalidate entries
+		if (x && (x == ppu->fifo.x)) {
+			ppu->fifo.obj = ppu->ost.data[i];
+#if 0
+			ppu->ost.data[i] &= 0xffffff00;
+#else
+			ppu->ost.data[i] = 0;
+#endif
+			return true;
+		}
+	}
+	return false;
+}
+
+static void shit_out_pixel (GBPPU *ppu) {
+	ppu->fifo.shift_out = (ppu->fifo.shift_out & 0xf0) | ppu->fifo.data >> 60;
+	ppu->fifo.data = ppu->fifo.data << 4;
+	ppu->fifo.n_fpixel--;
+	if (ppu->fifo.dx) {
+		//discard pixel
+		ppu->fifo.dx--;
+		return;
+	}
+	ut8 color;
+	if (!(ppu->fifo.shift_out & 0x08)) {
+		//bg pallet
+		color = (ppu->buf[GB_PPU_BGP] & (0x3 << ((ppu->fifo.shift_out & 0x3) << 1))) >>
+			((ppu->fifo.shift_out & 0x3) << 1);
+	} else {
+		const ut8 pal = !!(ppu->fifo.shift_out & 0x04);
+		color = (ppu->buf[GB_PPU_OBP0 + pal] & (0x3 << ((ppu->fifo.shift_out & 0x3) << 1))) >>
+			((ppu->fifo.shift_out & 0x3) << 1);
+	}
+#if 0
+	if (ppu->fifo.x > 7) {	//is this correct?
+		gb_pix_buf_set_pixel (ppu->pixbuf, ppu->fifo.x, ppu->buf[GB_PPU_LY], color);
+	}
+#endif
+	gb_pix_buf_set_pixel (ppu->pixbuf, ppu->fifo.x, ppu->buf[GB_PPU_LY], color);
+	ppu->fifo.x++;
+}
+
 static void gb_ppu_render_launch (GB *gb) {
 	RIOMap *vram = r_io_map_get (gb->io, gb->ppu->vram_mapid);
 	vram->perm = 0;	//disable vram access for rendering
@@ -337,6 +391,8 @@ static ut32 gb_ppu_render_continue (GB *gb, ut32 cycles) {
 	}
 	while (cycles) {
 		if (fifo->n_fpixel < 9) {
+			//initial phase on each line
+			//also when window starts?
 			gb_pixel_fifo_fetch_continue (gb);
 			if (fifo->flags & GB_PIXEL_FIFO_FETCH_READY) {
 				if (!fifo->n_fpixel) {
@@ -350,6 +406,26 @@ static ut32 gb_ppu_render_continue (GB *gb, ut32 cycles) {
 				fifo->flags ^= GB_PIXEL_FIFO_FETCH_READY;
 				fifo->fetcher[0].state_ctr = 0;
 			}
+		} else {
+			if (!(fifo->flags & GB_PIXEL_FIFO_FETCH_OBJECT)) {
+				if (check_objects (gb->ppu)) {
+					fifo->flags |= GB_PIXEL_FIFO_FETCH_OBJECT;
+				} else {
+					shit_out_pixel (gb->ppu);
+				}
+				gb_pixel_fifo_fetch_continue (gb);
+				if (fifo->n_fpixel < 9 && (fifo->flags & GB_PIXEL_FIFO_FETCH_READY)) {
+					fifo->data |= fifo->fetcher[0].fetched;
+					fifo->n_fpixel += 8;
+					fifo->flags ^= GB_PIXEL_FIFO_FETCH_READY;
+				}
+			} else {
+				gb_pixel_fifo_fetch_continue (gb);
+				if (fifo->flags & GB_PIXEL_FIFO_FETCH_READY) {
+					gb_ppu_pixel_fifo_merge_opixels (fifo);
+					fifo->flags ^= GB_PIXEL_FIFO_FETCH_OBJECT | GB_PIXEL_FIFO_FETCH_READY;
+				}
+			}
 		}
 		fifo->remaining_cycles--;
 		cycles--;