LCD Driver, some teensy code, SDCard code, MBR/FAT32

ext/sd/fat32/FS.h

@@ -0,0 +1,100 @@
+#pragma once
+
+#include <cstdint>
+#include "Structs.h"
+
+// https://www.pjrc.com/tech/8051/ide/fat32.html
+namespace FAT32 {
+
+	template <typename BlockDev> class FS {
+
+		static constexpr const char* NAME = "FAT32";
+
+		BlockDev& dev;
+		AbsOffset offset;
+
+
+		FSDesc desc;
+		Precomputed tmp;
+		bool valid = false;
+
+
+	public:
+
+		#include "File.h"
+		#include "DirIterator.h"
+
+		/** ctor with the absolute offset addr (in bytes) */
+		FS(BlockDev& dev, AbsOffset offset) : dev(dev), offset(offset) {
+			init();
+		}
+
+		/** is the detected FS valid? */
+		bool isValid() const {
+			return valid;
+		}
+
+		/** get an iterator for the root directory */
+		DirIterator getRoot() {
+			return DirIterator(*this, desc.rootDirFirstCluster);
+		}
+
+		/** open the given file for reading*/
+		File open(const DirEntry& de) {
+			return File(*this, de.getFirstCluster(), de.size);
+		}
+
+	private:
+
+		void init() {
+
+			debugMod3(NAME")
+			uint8_t buf[512];
+			dev.read(offset, 512, buf);
+
+			desc.bytesPerSector =		getU16(&buf[0x0B]);
+			desc.sectorsPerCluster =	getU8(&buf[0x0D]);
+			desc.numReservedSectors =	getU16(&buf[0x0E]);
+			desc.numberOfFATs = 		getU8(&buf[0x10]);
+			desc.sectorsPerFAT = 		getU32(&buf[0x24]);
+			desc.rootDirFirstCluster =	getU32(&buf[0x2C]);
+
+			// basic sanity check based on constants
+			valid = (desc.bytesPerSector == 512) && (desc.numberOfFATs == 2) && (getU16(&buf[0x1FE]) == 0xAA55);
+
+			tmp.bytesPerCluster =				desc.sectorsPerCluster * desc.bytesPerSector;
+			tmp.startOfFAT =					offset + (desc.numReservedSectors * desc.bytesPerSector);
+			tmp.startOfFirstDataCluster =		offset + (desc.numReservedSectors * desc.bytesPerSector) + (desc.numberOfFATs * desc.sectorsPerFAT * desc.bytesPerSector);
+			tmp.startOfFirstRootDirCluster =	clusterToAbsPos(desc.rootDirFirstCluster);
+			tmp.dirEntriesPerSector =			desc.bytesPerSector / sizeof(DirEntry);
+
+			/*
+			std::cout << (int)desc.bytesPerSector << std::endl;
+			std::cout << (int)desc.sectorsPerCluster << std::endl;
+			std::cout << (int)desc.numReservedSectors << std::endl;
+			std::cout << (int)desc.numberOfFATs << std::endl;
+			std::cout << (int)desc.sectorsPerFAT << std::endl;
+			std::cout << (int)desc.rootDirFirstCluster << std::endl;
+
+			std::cout << tmp.startOfFAT << std::endl;
+			std::cout << tmp.startOfFirstDataCluster << std::endl;
+			std::cout << tmp.startOfFirstRootDirCluster << std::endl;
+			*/
+
+		}
+
+		/** determine the ClusterNr following the given ClusterNr */
+		ClusterNr getNextCluster(ClusterNr clusterNr) {
+			const AbsPos pos = tmp.startOfFAT + ((clusterNr) * sizeof(uint32_t));
+			ClusterNr next;
+			int read = dev.read(pos, 4, reinterpret_cast<uint8_t*>(&next));
+			return next;
+		}
+
+		/** convert ClusterNr into an absolute position on disk */
+		AbsPos clusterToAbsPos(ClusterNr clusterNr) {
+			return tmp.startOfFirstDataCluster + ((clusterNr - 2) * desc.sectorsPerCluster * desc.bytesPerSector);
+		}
+
+	};
+}