Add Avalon-MM emulator

2 files changed, 108 insertions, 0 deletions

diff --git a/tb/avalon.hpp b/tb/avalon.hpp
new file mode 100644
index 0000000..38c8792
--- /dev/null
+++ b/tb/avalon.hpp
@@ -0,0 +1,46 @@
+#ifndef AVALON_HPP
+#define AVALON_HPP
+
+#include <cstdint>
+#include <vector>
+
+namespace taller::avalon
+{
+	class slave
+	{
+		public:
+			virtual std::uint32_t base_address() = 0;
+			virtual std::uint32_t address_mask() = 0;
+
+			virtual bool read(std::uint32_t addr, std::uint32_t &data) = 0;
+			virtual bool write(std::uint32_t addr, std::uint32_t data, unsigned byte_enable) = 0;
+	};
+
+	template<class Platform>
+	class interconnect
+	{
+		public:
+			inline interconnect(Platform &plat) noexcept
+			: plat(plat)
+			{}
+
+			void tick();
+			void attach(slave &dev);
+
+		private:
+			struct binding
+			{
+				std::uint32_t base;
+				std::uint32_t mask;
+				slave         &dev;
+			};
+
+			Platform            &plat;
+			slave*               active = nullptr;
+			std::vector<binding> devices;
+	};
+}
+
+#include "avalon.impl.hpp"
+
+#endif
diff --git a/tb/avalon.impl.hpp b/tb/avalon.impl.hpp
new file mode 100644
index 0000000..7f589ae
--- /dev/null
+++ b/tb/avalon.impl.hpp
@@ -0,0 +1,62 @@
+#ifndef AVALON_IMPL_HPP
+#define AVALON_IMPL_HPP
+
+#include <cassert>
+#include <cstdio>
+
+namespace taller::avalon
+{
+	template<class Platform>
+	void interconnect<Platform>::attach(slave &dev)
+	{
+		devices.push_back(binding { dev.base_address(), dev.address_mask(), dev });
+	}
+
+	template<class Platform>
+	void interconnect<Platform>::tick()
+	{
+		auto addr = plat.avl_address;
+		if(!active)
+		{
+			if(addr & 0b11)
+			{
+				fprintf(stderr, "[avl] unaligned address: 0x%08x\n", addr);
+				assert(false);
+			}
+
+			for(auto &binding : devices)
+			{
+				if((addr & binding.mask) == binding.base)
+				{
+					active = &binding.dev;
+					break;
+				}
+			}
+
+			if(!active)
+			{
+				const char *op = plat.avl_read ? "read" : "write";
+				fprintf(stderr, "[avl] attempt to %s memory hole at 0x%08x\n", op, addr);
+				assert(false);
+			}
+		}
+
+		assert(!plat.avl_read || !plat.avl_write);
+		auto pos = addr >> 2;
+
+		if(plat.avl_read)
+		{
+			plat.avl_waitrequest = !active->read(pos, plat.avl_readdata);
+		} else if(plat.avl_write)
+		{
+			plat.avl_waitrequest = !active->write(pos, plat.avl_writedata, plat.avl_byteenable);
+		}
+
+		if(!plat.avl_waitrequest)
+		{
+			active = nullptr;
+		}
+	}
+}
+
+#endif