78 lines
2.1 KiB
C++
78 lines
2.1 KiB
C++
#pragma once
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#include <cstdint>
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#include <string>
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namespace FAT32 {
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using ClusterNr = uint32_t;
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using AbsOffset = uint32_t;
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using AbsPos = uint32_t;
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struct FSDesc {
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uint16_t bytesPerSector;
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uint8_t sectorsPerCluster;
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uint16_t numReservedSectors;
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uint8_t numberOfFATs;
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uint32_t sectorsPerFAT;
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ClusterNr rootDirFirstCluster;
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};
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struct Precomputed {
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uint32_t bytesPerCluster;
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AbsPos startOfFAT; // absolute byte offset where the FAT begins
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AbsPos startOfFirstDataCluster; // absolute byte offset where the first cluster is
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AbsPos startOfFirstRootDirCluster; // absolute byte offset where the first root dir cluster is
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uint32_t dirEntriesPerSector;
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};
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union Attributes {
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uint8_t raw;
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struct {
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uint8_t readOnly : 1;
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uint8_t hidden : 1;
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uint8_t system : 1;
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uint8_t volumeID : 1;
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uint8_t directory : 1;
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uint8_t archive : 1;
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uint8_t unused1 : 1;
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uint8_t unused2 : 1;
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} bits;
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} __attribute__((packed));
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struct DirEntry {
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unsigned char name[8];
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unsigned char ext[3];
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Attributes attr;
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uint8_t dummy1[8];
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uint16_t firstClusterHi;
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uint8_t dummy2[4];
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uint16_t firstClusterLo;
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uint32_t size; // file size in bytes
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bool isUnused() const {return name[0] == 0xE5;}
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bool isDirectory() const {return attr.bits.directory;}
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bool isEndOfDirectory() const {return name[0] == 0x00;}
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bool isLongFileName() const {return (attr.raw & 0b1111) == 0b1111;}
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uint32_t getFirstCluster() const {return firstClusterHi<<16 | firstClusterLo<<0;}
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std::string getName() const {
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char buf[16];
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uint8_t pos = 0;
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for (uint8_t i = 0; i < 8; ++i) {if (name[i] != ' ') {buf[pos++] = name[i];}}
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buf[pos++] = '.';
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for (uint8_t i = 0; i < 8; ++i) {if ( ext[i] != ' ') {buf[pos++] = ext[i];}}
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buf[pos] = 0;
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return std::string(buf);
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}
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} __attribute__((packed));
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static inline uint16_t getU8(const uint8_t* src) {return src[0];}
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static inline uint16_t getU16(const uint8_t* src) {return src[0]<<0 | src[1]<<8;}
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static inline uint32_t getU32(const uint8_t* src) {return src[0]<<0 | src[1]<<8 | src[2]<<16 | src[3]<<24;}
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}
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