From 6d96109ff7882d5f59bbced2b6a4d7d30cf3e95c Mon Sep 17 00:00:00 2001
From: Nick Renieris <velocityra@gmail.com>
Date: Wed, 1 Apr 2020 01:02:24 +0300
Subject: [PATCH] Qt/Debugger: Don't move entire list if it's not needed

With 4 buffer spaces at the bottom.
---
 rpcs3/rpcs3qt/debugger_list.cpp | 41 +++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/rpcs3/rpcs3qt/debugger_list.cpp b/rpcs3/rpcs3qt/debugger_list.cpp
index d14a349c3985..bc540101e4a3 100644
--- a/rpcs3/rpcs3qt/debugger_list.cpp
+++ b/rpcs3/rpcs3qt/debugger_list.cpp
@@ -58,22 +58,31 @@ void debugger_list::ShowAddress(u32 addr)
 		return m_breakpoint_handler->HasBreakpoint(pc);
 	};
 
-	if (xgui_settings->GetValue(gui::d_centerPC).toBool())
-	{
-		m_pc = GetCenteredAddress(addr);
-	}
-	else
+	const bool center_pc = xgui_settings->GetValue(gui::d_centerPC).toBool();
+
+	// How many spaces addr can move down without us needing to move the entire view
+	const u32 addr_margin = (m_item_count / (center_pc ? 2 : 1) - 4); // 4 is just a buffer of 4 spaces at the bottom
+
+	if (s32(addr) - m_pc > addr_margin * 4) // 4 is the number of bytes in each instruction
 	{
-		m_pc = addr;
+		if (center_pc)
+		{
+			m_pc = GetCenteredAddress(addr);
+		}
+		else
+		{
+			m_pc = addr;
+		}
 	}
 
 	const auto cpu = this->cpu.lock();
 
 	if (!cpu)
 	{
-		for (uint i = 0; i < m_item_count; ++i, m_pc += 4)
+		u32 pc = m_pc;
+		for (uint i = 0; i < m_item_count; ++i, pc += 4)
 		{
-			item(i)->setText(qstr(fmt::format("   [%08x] illegal address", m_pc)));
+			item(i)->setText(qstr(fmt::format("   [%08x] illegal address", pc)));
 		}
 	}
 	else
@@ -83,25 +92,27 @@ void debugger_list::ShowAddress(u32 addr)
 		const u32 address_limits = (is_spu ? 0x3fffc : ~3);
 		m_pc &= address_limits;
 		m_disasm->offset = vm::get_super_ptr(cpu_offset);
-		for (uint i = 0, count = 4; i<m_item_count; ++i, m_pc = (m_pc + count) & address_limits)
+		u32 pc = m_pc;
+
+		for (uint i = 0, count = 4; i<m_item_count; ++i, pc = (pc + count) & address_limits)
 		{
-			if (!vm::check_addr(cpu_offset + m_pc, 4))
+			if (!vm::check_addr(cpu_offset + pc, 4))
 			{
-				item(i)->setText((IsBreakpoint(m_pc) ? ">> " : "   ") + qstr(fmt::format("[%08x] illegal address", m_pc)));
+				item(i)->setText((IsBreakpoint(pc) ? ">> " : "   ") + qstr(fmt::format("[%08x] illegal address", pc)));
 				count = 4;
 				continue;
 			}
 
-			count = m_disasm->disasm(m_disasm->dump_pc = m_pc);
+			count = m_disasm->disasm(m_disasm->dump_pc = pc);
 
-			item(i)->setText((IsBreakpoint(m_pc) ? ">> " : "   ") + qstr(m_disasm->last_opcode));
+			item(i)->setText((IsBreakpoint(pc) ? ">> " : "   ") + qstr(m_disasm->last_opcode));
 
-			if (cpu->is_paused() && m_pc == GetPc())
+			if (cpu->is_paused() && pc == GetPc())
 			{
 				item(i)->setForeground(m_text_color_pc);
 				item(i)->setBackground(m_color_pc);
 			}
-			else if (IsBreakpoint(m_pc))
+			else if (IsBreakpoint(pc))
 			{
 				item(i)->setForeground(m_text_color_bp);
 				item(i)->setBackground(m_color_bp);