From 9266507e4cbed7bfbf56fdbc107d46f54497bc79 Mon Sep 17 00:00:00 2001
From: Eladash <elad3356p@gmail.com>
Date: Tue, 12 May 2020 19:17:50 +0300
Subject: [PATCH] SPU: Implement spu_channel_(4_)t::try_read

---
 rpcs3/Emu/Cell/SPUThread.cpp   | 12 ++++++------
 rpcs3/Emu/Cell/SPUThread.h     | 34 +++++++++++++++++++++++++++++++++-
 rpcs3/Emu/Cell/lv2/sys_spu.cpp |  6 +++---
 3 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/rpcs3/Emu/Cell/SPUThread.cpp b/rpcs3/Emu/Cell/SPUThread.cpp
index f6c3e122cc..6a223535c1 100644
--- a/rpcs3/Emu/Cell/SPUThread.cpp
+++ b/rpcs3/Emu/Cell/SPUThread.cpp
@@ -995,8 +995,8 @@ void spu_thread::cpu_stop()
 					if (thread && thread.get() != this && thread->status_npc.load().status >> 16 == SYS_SPU_THREAD_STOP_THREAD_EXIT)
 					{
 						// Wait for all threads to have error codes if exited by sys_spu_thread_exit
-						for (u64 status; ((status = thread->exit_status.data) & spu_channel::bit_count) == 0
-							|| static_cast<u32>(status) != thread->last_exit_status;)
+						for (u32 status; !thread->exit_status.try_read(status)
+							|| status != thread->last_exit_status;)
 						{
 							_mm_pause();
 						} 
@@ -3288,11 +3288,11 @@ void fmt_class_string<spu_channel>::format(std::string& out, u64 arg)
 {
 	const auto& ch = get_object(arg);
 
-	const u64 raw = ch.data.load();
+	u32 data = 0;
 
-	if (raw & spu_channel::bit_count)
+	if (ch.try_read(data))
 	{
-		fmt::append(out, "0x%08x", static_cast<u32>(raw));
+		fmt::append(out, "0x%08x", data);
 	}
 	else
 	{
@@ -3305,7 +3305,7 @@ void fmt_class_string<spu_channel_4_t>::format(std::string& out, u64 arg)
 {
 	const auto& ch = get_object(arg);
 
-	// TODO
+	// TODO (use try_read)
 	fmt::append(out, "count = %d", ch.get_count());
 }
 
diff --git a/rpcs3/Emu/Cell/SPUThread.h b/rpcs3/Emu/Cell/SPUThread.h
index 34767fde85..8de43c215d 100644
--- a/rpcs3/Emu/Cell/SPUThread.h
+++ b/rpcs3/Emu/Cell/SPUThread.h
@@ -233,6 +233,20 @@ public:
 		return (old & bit_count) != 0;
 	}
 
+	// Reading without modification
+	bool try_read(u32& out) const
+	{
+		const u64 old = data.load();
+
+		if (old & bit_count) [[likely]]
+		{
+			out = static_cast<u32>(old);
+			return true;
+		}
+
+		return false;
+	}
+
 	// Pop unconditionally (loading last value), may require notification
 	u32 pop(cpu_thread& spu)
 	{
@@ -269,6 +283,7 @@ struct spu_channel_4_t
 	{
 		u8 waiting;
 		u8 count;
+		u8 _pad[2];
 		u32 value0;
 		u32 value1;
 		u32 value2;
@@ -338,6 +353,23 @@ public:
 		});
 	}
 
+	// returns current queue size without modification
+	uint try_read(u32 (&out)[4]) const
+	{
+		const sync_var_t data = values.load();
+		const uint result = data.count;
+
+		if (result != 0)
+		{
+			out[0] = data.value0;
+			out[1] = data.value1;
+			out[2] = data.value2;
+			out[3] = value3;
+		}
+
+		return result;
+	}
+
 	u32 get_count() const
 	{
 		return std::as_const(values).raw().count;
@@ -345,7 +377,7 @@ public:
 
 	void set_values(u32 count, u32 value0, u32 value1 = 0, u32 value2 = 0, u32 value3 = 0)
 	{
-		this->values.raw() = { 0, static_cast<u8>(count), value0, value1, value2 };
+		this->values.raw() = { 0, static_cast<u8>(count), {}, value0, value1, value2 };
 		this->value3 = value3;
 	}
 };
diff --git a/rpcs3/Emu/Cell/lv2/sys_spu.cpp b/rpcs3/Emu/Cell/lv2/sys_spu.cpp
index 3aabe5012c..a9a24a0745 100644
--- a/rpcs3/Emu/Cell/lv2/sys_spu.cpp
+++ b/rpcs3/Emu/Cell/lv2/sys_spu.cpp
@@ -482,11 +482,11 @@ error_code sys_spu_thread_get_exit_status(ppu_thread& ppu, u32 id, vm::ptr<s32>
 		return CELL_ESRCH;
 	}
 
-	const u64 exit_status = thread->exit_status.data.load();
+	u32 data;
 
-	if (exit_status & spu_channel::bit_count)
+	if (thread->exit_status.try_read(data))
 	{
-		*status = static_cast<s32>(exit_status);
+		*status = static_cast<s32>(data);
 		return CELL_OK;
 	}