From 5735df623adbd68514438baa68cffe0aa4fe866d Mon Sep 17 00:00:00 2001
From: condret <condr3t@protonmail.com>
Date: Fri, 15 Nov 2024 00:45:01 +0100
Subject: [PATCH] rework the interrupt mechanism

---
 include/gb.h    | 17 +++++++++--------
 io/interrupts.c | 38 +++++++++++++++++++++-----------------
 io/ppu.c        |  6 ++++++
 3 files changed, 36 insertions(+), 25 deletions(-)

diff --git a/include/gb.h b/include/gb.h
index 96a26f1..b4522cc 100644
--- a/include/gb.h
+++ b/include/gb.h
@@ -55,8 +55,7 @@ void gb_joypad_fini(GBJoypad *joypad, RIO *io);
 typedef struct gb_interrupts_t {
 	RRegItem *ime;
 	int fd;
-	ut16 flags;
-//	ut16 pc;
+	ut32 flags;
 } GBInterrupts;
 
 enum {
@@ -65,16 +64,17 @@ enum {
 	GB_INTERRUPT_TIMER,
 	GB_INTERRUPT_SERIAL,
 	GB_INTERRUPT_JOYPAD,
-	GB_INTERRUPT_N,		//number of interrupts
+	GB_INTERRUPT_N,					//number of interrupts
 	GB_INTERRUPT_VBLANK_ENABLED = GB_INTERRUPT_N,
 	GB_INTERRUPT_STAT_ENABLED,
 	GB_INTERRUPT_TIMER_ENABLED,
 	GB_INTERRUPT_SERIAL_ENABLED,
 	GB_INTERRUPT_JOYPAD_ENABLED,
-	GB_INTERRUPT_ENABLED,		//general enable of all interrupts
-	GB_INTERRUPT_ENABLE_WAIT,	//wait 1 instruction befor enabling interrupts
-	GB_INTERRUPT_WAIT_TRIGGER,	//gb was put in wait state on previous call
-	GB_INTERRUPT_SEEK,		//2 bits for seek
+	GB_INTERRUPT_ENABLED,				//general enable of all interrupts
+	GB_INTERRUPT_ENABLE_WAIT,			//wait 1 instruction befor enabling interrupts
+	GB_INTERRUPT_WAIT_TRIGGER,			//gb was put in wait state on previous call
+	GB_INTERRUPT_SEEK,				//2 bits for seek
+	GB_INTERRUPT_PENDING = GB_INTERRUPT_SEEK + 2,	//3 bits for pending interrupt
 };
 
 bool gb_interrupts_init(GBInterrupts *ints, RIO *io, RReg *reg);
@@ -233,7 +233,8 @@ typedef struct gameboy_t {
 	GBPPU *ppu;
 	ut64 addr;
 	int cartrigde_fd;
-	bool double_speed;
+	ut32 pause_cycles;
+//	bool double_speed;
 } GB;
 
 void gb_interrupts_request(GB *gb, int interrupt);
diff --git a/io/interrupts.c b/io/interrupts.c
index d9ff29d..f447948 100644
--- a/io/interrupts.c
+++ b/io/interrupts.c
@@ -129,29 +129,33 @@ void gb_interrupts_continue(GB *gb) {
 		gb->interrupts.flags |= (0x1 << GB_INTERRUPT_ENABLE_WAIT);
 		return;
 	} else if (!ime) {
-		gb->interrupts.flags &= ~0xe00;
+		gb->interrupts.flags &= 0x3ff;
 		return;
 	}
-	ut32 i;
-	for (i = 0; i < GB_INTERRUPT_N; i++) {
-		const ut16 imask = (0x1 << i) | (0x1 << (i + GB_INTERRUPT_N));
-		if ((gb->interrupts.flags & imask) == imask) {
-			goto beach;
-		}
-		//remove requests for disabled interrupts
-		gb->interrupts.flags &= ~(0x1 << i);
-	}
-	return;
-beach:
 	if (!(gb->interrupts.flags & (0x1 << GB_INTERRUPT_WAIT_TRIGGER))) {
-		gb->interrupts.flags |= (0x1 << GB_INTERRUPT_WAIT_TRIGGER);
-		//stop exection of instructions for 20 cycles
-		//gb_pause_exec (gb, 20);
+		ut32 i;
+		for (i = 0; i < GB_INTERRUPT_N; i++) {
+			const ut16 imask = (0x1 << i) | (0x1 << (i + GB_INTERRUPT_N));
+			if ((gb->interrupts.flags & imask) == imask) {
+				gb->interrupts.flags |= (0x1 << GB_INTERRUPT_WAIT_TRIGGER);
+				//stop exection of instructions for 20 cycles
+				//gb_pause_exec (gb, 20);
+				gb->pause_cycles += 20;
+				//save pending interrupt index
+				gb->interrupts.flags &= ~(0x7 << GB_INTERRUPT_PENDING);
+				gb->interrupts.flags |= (i << GB_INTERRUPT_PENDING);
+				return;
+			}
+		}
 		return;
 	}
-	const ut64 interrupt_vector = 0x40 + (i << 3);
+	gb->interrupts.flags ^= 0x1 << GB_INTERRUPT_WAIT_TRIGGER;
+	const ut32 interrupt = (gb->interrupts.flags & (0x7 << GB_INTERRUPT_PENDING)) >> GB_INTERRUPT_PENDING;
+	gb->interrupts.flags &= ~(0x1 << interrupt);
+	const ut64 interrupt_vector = 0x40 + (interrupt << 3);
 	//maybe make this a static buffer?
-	char *interrupt_expr = r_str_newf ("2,sp,-=,pc,sp,=[2],0x%"PFMT64x",pc,:=", interrupt_vector);
+	char *interrupt_expr = r_str_newf (
+		"0,ime,:=,2,sp,-=,pc,sp,=[2],0x%"PFMT64x",pc,:=", interrupt_vector);
 	r_esil_parse (gb->esil, interrupt_expr);
 	free (interrupt_expr);
 }
diff --git a/io/ppu.c b/io/ppu.c
index b115dad..52869e2 100644
--- a/io/ppu.c
+++ b/io/ppu.c
@@ -463,6 +463,12 @@ static ut32 gb_ppu_render_continue (GB *gb, ut32 cycles) {
 					fifo->flags |= GB_PIXEL_FIFO_FETCH_OBJECT;
 				} else {
 					shit_out_pixel (gb->ppu);
+					if (fifo->x > 159) {
+						gb->ppu->buf[GB_PPU_STAT] &= ~GB_PPU_STAT_MODE_MASK;
+						gb->ppu->buf[GB_PPU_STAT] |= GB_PPU_STAT_MODE_HBLANK;
+						fifo->remaining_cycles--;
+						return cycles - 1;
+					}
 				}
 				gb_pixel_fifo_fetch_continue (gb);
 				if (fifo->n_fpixel < 9 && (fifo->flags & GB_PIXEL_FIFO_FETCH_READY)) {