DSP: Fix sln file now that old LLE is dead. Add preliminary DSPAnalyzer, which looks for idle skip opportunities.

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@2930 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Plugins/Plugin_DSP_LLE-testing/Src/DSPAnalyzer.cpp

@@ -0,0 +1,104 @@
+// Copyright (C) 2003-2009 Dolphin Project.
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, version 2.0.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License 2.0 for more details.
+
+// A copy of the GPL 2.0 should have been included with the program.
+// If not, see http://www.gnu.org/licenses/
+
+// Official SVN repository and contact information can be found at
+// http://code.google.com/p/dolphin-emu/
+
+#include "DSPAnalyzer.h"
+#include "DSPInterpreter.h"
+#include "DSPTables.h"
+#include "gdsp_memory.h"
+
+namespace DSPAnalyzer {
+
+// Holds data about all instructions in RAM.
+u8 inst_flags[ISPACE];
+
+// Good candidates for idle skipping is mail wait loops. If we're time slicing
+// between the main CPU and the DSP, if the DSP runs into one of these, it might
+// as well give up its time slice immediately.
+
+// Max signature length is 6. A 0 in a signature is ignored.
+#define NUM_IDLE_SIGS 2
+#define MAX_IDLE_SIG_SIZE 6
+const u16 idle_skip_sigs[NUM_IDLE_SIGS][MAX_IDLE_SIG_SIZE + 1] =
+{
+	{ 0x27fc,          // LRS $31, @DMBH
+	  0x03c0, 0x8000,  // ANDCF $31, #0x8000
+	  0x029d, 0x027a,  // JLZ 0x027a
+	  0x02df, 0 },     // RET
+	{ 0x27fe,          // LRS $31, @CMBH
+	  0x03c0, 0x8000,  // ANDCF $31, #0x8000
+	  0x029c, 0x0280,  // JLNZ 0x0280
+	  0x02df, 0 },     // RET
+};
+
+void Reset()
+{
+	memset(inst_flags, 0, sizeof(inst_flags));
+}
+
+void AnalyzeRange(int start_addr, int end_addr)
+{
+	// First we run an extremely simplified version of a disassembler to find
+	// where all instructions start.
+
+	// This may not be 100% accurate in case of jump tables, but should be good
+	// enough as a start.
+	int addr = start_addr;
+	while (addr < end_addr)
+	{
+		UDSPInstruction inst = dsp_imem_read(addr);
+		const DSPOPCTemplate *opcode = GetOpTemplate(inst);
+		if (!opcode)
+		{
+			addr++;
+			continue;
+		}
+		inst_flags[addr] |= CODE_START_OF_INST;
+		addr += opcode->size;
+	}
+
+	// Next, we'll scan for potential idle skips.
+	for (int s = 0; s < NUM_IDLE_SIGS; s++)
+	{
+		for (int addr = start_addr; addr < end_addr; addr++)
+		{
+			bool found = false;
+			for (int i = 0; i < MAX_IDLE_SIG_SIZE + 1; i++)
+			{
+				if (idle_skip_sigs[s][i] == 0)
+					found = true;
+				if (idle_skip_sigs[s][i] != dsp_imem_read(addr + i))
+					break;
+			}
+			if (found)
+			{
+				NOTICE_LOG(DSPLLE, "Idle skip location found at %02x", addr);
+				inst_flags[addr] |= CODE_IDLE_SKIP;
+				// TODO: actually use this flag somewhere.
+			}
+		}
+	}
+	NOTICE_LOG(DSPLLE, "Finished analysis.");
+}
+
+void Analyze()
+{
+	Reset();
+	AnalyzeRange(0x0000, 0x1000);  // IRAM
+	AnalyzeRange(0x8000, 0x9000);  // IROM
+}
+
+}  // namespace