From 1a3b53253059e6a3974bb123d84d4a589e63384b Mon Sep 17 00:00:00 2001
From: refractionpcsx2 <refraction@gmail.com>
Date: Fri, 2 Oct 2020 15:44:48 +0100
Subject: [PATCH] SIF: Transfer SIF0 junk for partial QW transfers from IOP
 Fixes True Crime: Streets of LA

---
 pcsx2/Sif.h    | 22 +++++++++++++++++++++-
 pcsx2/Sif0.cpp | 22 +++++++++++++++-------
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/pcsx2/Sif.h b/pcsx2/Sif.h
index 8ce56a70ea..8561b2a41c 100644
--- a/pcsx2/Sif.h
+++ b/pcsx2/Sif.h
@@ -37,6 +37,7 @@ struct sifData
 struct sifFifo
 {
 	u32 data[FIFO_SIF_W];
+	u32 junk[4];
 	s32 readPos;
 	s32 writePos;
 	s32 size;
@@ -52,7 +53,10 @@ struct sifFifo
 		{
 			const int wP0 = std::min((FIFO_SIF_W - writePos), words);
 			const int wP1 = words - wP0;
-
+			if (size < 4)
+			{
+				memcpy(&junk[size], from, (4 - size) << 2);
+			}
 			memcpy(&data[writePos], from, wP0 << 2);
 			memcpy(&data[0], &from[wP0], wP1 << 2);
 
@@ -62,6 +66,22 @@ struct sifFifo
 		SIF_LOG("  SIF + %d = %d (pos=%d)", words, size, writePos);
 	}
 
+	void writeJunk(int words)
+	{
+		if (words > 0)
+		{
+			const int wP0 = std::min((FIFO_SIF_W - writePos), words);
+			const int wP1 = words - wP0;
+
+			memcpy(&data[writePos], &junk[4-words], wP0 << 2);
+			memcpy(&data[0], &junk[(4 - words)+wP0], wP1 << 2);
+
+			writePos = (writePos + words) & (FIFO_SIF_W - 1);
+			size += words;
+		}
+		SIF_LOG("  SIF + %d = %d (pos=%d)", words, size, writePos);
+	}
+
 	void read(u32 *to, int words)
 	{
 		if (words > 0)
diff --git a/pcsx2/Sif0.cpp b/pcsx2/Sif0.cpp
index 05a814a61b..5c86646b33 100644
--- a/pcsx2/Sif0.cpp
+++ b/pcsx2/Sif0.cpp
@@ -23,6 +23,7 @@
 _sif sif0;
 
 static bool done = false;
+static int writeJunk = 0;
 
 static __fi void Sif0Init()
 {
@@ -83,6 +84,12 @@ static __fi bool WriteIOPtoFifo()
 	sif0.iop.cycles += (writeSize >> 2)/* * BIAS*/;		// fixme : should be >> 4
 	sif0.iop.counter -= writeSize;
 
+	if (sif0.iop.counter == 0 && writeJunk)
+	{
+		SIF_LOG("Writing Junk %d", writeJunk);
+		sif0.fifo.writeJunk(writeJunk);
+		writeJunk = 0;
+	}
 	return true;
 }
 
@@ -92,7 +99,7 @@ static __fi bool ProcessEETag()
 	static __aligned16 u32 tag[4];
 	tDMA_TAG& ptag(*(tDMA_TAG*)tag);
 
-	sif0.fifo.read((u32*)&tag[0], 4); // Tag
+	sif0.fifo.read((u32*)&tag[0], 2); // Tag
 	SIF_LOG("SIF0 EE read tag: %x %x %x %x", tag[0], tag[1], tag[2], tag[3]);
 
 	sif0ch.unsafeTransfer(&ptag);
@@ -128,26 +135,27 @@ static __fi bool ProcessIOPTag()
 {
 	// Process DMA tag at hw_dma9.tadr
 	sif0.iop.data = *(sifData *)iopPhysMem(hw_dma9.tadr);
-	sif0.iop.data.words = (sif0.iop.data.words + 3) & 0xfffffffc; // Round up to nearest 4.
+	sif0.iop.data.words = sif0.iop.data.words;
 
 	// send the EE's side of the DMAtag.  The tag is only 64 bits, with the upper 64 bits
 	// ignored by the EE.
 
 	sif0.fifo.write((u32*)iopPhysMem(hw_dma9.tadr + 8), 2);
-	sif0.fifo.writePos = (sif0.fifo.writePos + 2) & (FIFO_SIF_W - 1);		// iggy on the upper 64.
-	sif0.fifo.size += 2;
+	//sif0.fifo.writePos = (sif0.fifo.writePos + 2) & (FIFO_SIF_W - 1);		// iggy on the upper 64.
+	//sif0.fifo.size += 2;
 
 	hw_dma9.tadr += 16; ///hw_dma9.madr + 16 + sif0.sifData.words << 2;
 
 	// We're only copying the first 24 bits.  Bits 30 and 31 (checked below) are Stop/IRQ bits.
 	hw_dma9.madr = sif0data & 0xFFFFFF;
-	if (sif0words > 0xFFFFC) DevCon.Warning("SIF0 Overrun %x", sif0words);
+	if (sif0words > 0xFFFFF) DevCon.Warning("SIF0 Overrun %x", sif0words);
 	//Maximum transfer amount 1mb-16 also masking out top part which is a "Mode" cache stuff, we don't care :)
-	sif0.iop.counter = sif0words & 0xFFFFC;
+	sif0.iop.counter = sif0words & 0xFFFFF;
 
+	writeJunk = (sif0.iop.counter & 0x3) ? (4 - sif0.iop.counter & 0x3) : 0;
 	// IOP tags have an IRQ bit and an End of Transfer bit:
 	if (sif0tag.IRQ  || (sif0tag.ID & 4)) sif0.iop.end = true;
-	SIF_LOG("SIF0 IOP Tag: madr=%lx, tadr=%lx, counter=%lx (%08X_%08X)", hw_dma9.madr, hw_dma9.tadr, sif0.iop.counter, sif0words, sif0data);
+	SIF_LOG("SIF0 IOP Tag: madr=%lx, tadr=%lx, counter=%lx (%08X_%08X) Junk %d", hw_dma9.madr, hw_dma9.tadr, sif0.iop.counter, sif0words, sif0data, writeJunk);
 
 	return true;
 }