Shader: Add SpirvDecoder

src/Nazara/Shader/SpirvDecoder.cpp

@@ -0,0 +1,87 @@
+// Copyright (C) 2020 Jérôme Leclercq
+// This file is part of the "Nazara Engine - Shader generator"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Shader/SpirvDecoder.hpp>
+#include <Nazara/Core/CallOnExit.hpp>
+#include <Nazara/Core/StackArray.hpp>
+#include <Nazara/Shader/SpirvData.hpp>
+#include <cassert>
+#include <iomanip>
+#include <sstream>
+#include <stdexcept>
+#include <Nazara/Shader/Debug.hpp>
+
+namespace Nz
+{
+	void SpirvDecoder::Decode(const UInt32* codepoints, std::size_t count)
+	{
+		m_currentCodepoint = codepoints;
+		m_codepointEnd = codepoints + count;
+
+		UInt32 magicNumber = ReadWord();
+		if (magicNumber != SpirvMagicNumber)
+			throw std::runtime_error("invalid Spir-V: magic number didn't match");
+
+		UInt32 versionNumber = ReadWord();
+		if (versionNumber > SpirvVersion)
+			throw std::runtime_error("Spir-V is more recent than decoder, dismissing");
+
+		SpirvHeader header;
+		header.generatorId = ReadWord();
+		header.bound = ReadWord();
+		header.schema = ReadWord();
+		header.versionNumber = versionNumber;
+
+		if (!HandleHeader(header))
+			return;
+
+		while (m_currentCodepoint < m_codepointEnd)
+		{
+			UInt32 firstWord = ReadWord();
+
+			UInt16 wordCount = static_cast<UInt16>((firstWord >> 16) & 0xFFFF);
+			UInt16 opcode = static_cast<UInt16>(firstWord & 0xFFFF);
+
+			const SpirvInstruction* inst = GetInstructionData(opcode);
+			if (!inst)
+				throw std::runtime_error("invalid instruction");
+
+			if (!HandleOpcode(*inst, wordCount))
+				break;
+
+			m_currentCodepoint += wordCount - 1;
+		}
+	}
+
+	bool SpirvDecoder::HandleHeader(const SpirvHeader& /*header*/)
+	{
+		return true;
+	}
+
+	std::string SpirvDecoder::ReadString()
+	{
+		std::string str;
+
+		for (;;)
+		{
+			UInt32 value = ReadWord();
+			for (std::size_t j = 0; j < 4; ++j)
+			{
+				char c = static_cast<char>((value >> (j * 8)) & 0xFF);
+				if (c == '\0')
+					return str;
+
+				str.push_back(c);
+			}
+		}
+	}
+
+	UInt32 SpirvDecoder::ReadWord()
+	{
+		if (m_currentCodepoint >= m_codepointEnd)
+			throw std::runtime_error("unexpected end of stream");
+
+		return *m_currentCodepoint++;
+	}
+}