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//! FAT32 Boot Sector (BPB)
const constants = @import("shared").fat32.constants;
pub const BootSector = extern struct {
JumpBoot: [3]u8,
OemName: [8]u8,
BytesPerSector: u16 align(1),
SectorsPerCluster: u8,
ReservedSectors: u16 align(1),
FatCount: u8,
RootEntryCount: u16 align(1),
TotalSectors16: u16 align(1),
MediaType: u8,
FatSize16: u16 align(1),
SectorsPerTrack: u16 align(1),
HeadCount: u16 align(1),
HiddenSectors: u32 align(1),
TotalSectors32: u32 align(1),
FatSize32: u32 align(1),
ExtFlags: u16 align(1),
FsVersion: u16 align(1),
RootCluster: u32 align(1),
FsInfoSector: u16 align(1),
BackupBootSector: u16 align(1),
Reserved: [12]u8,
DriveNumber: u8,
Reserved1: u8,
BootSignature: u8,
VolumeId: u32 align(1),
VolumeLabel: [11]u8,
FsType: [8]u8,
BootCode: [420]u8,
Signature: u16 align(1),
pub fn isValid(self: *const BootSector) bool {
if (self.Signature != constants.magic.BOOT_SIGNATURE) {
return false;
}
if (self.BytesPerSector < constants.sizes.SECTOR_SIZE_MIN or
self.BytesPerSector > constants.sizes.SECTOR_SIZE_MAX)
{
return false;
}
if (self.SectorsPerCluster == 0) {
return false;
}
if (self.FatCount == 0) {
return false;
}
if (self.FatSize32 == 0) {
return false;
}
return true;
}
pub fn getFatStartSector(self: *const BootSector) u32 {
return self.ReservedSectors;
}
pub fn getDataStartSector(self: *const BootSector) u32 {
return self.ReservedSectors + (@as(u32, self.FatCount) * self.FatSize32);
}
pub fn getTotalClusters(self: *const BootSector) u32 {
const data_sectors = self.TotalSectors32 - self.getDataStartSector();
return data_sectors / self.SectorsPerCluster;
}
pub fn clusterToSector(self: *const BootSector, cluster: u32) u32 {
return self.getDataStartSector() + ((cluster - constants.clusters.CLUSTER_DATA_START) * self.SectorsPerCluster);
}
pub fn getBytesPerCluster(self: *const BootSector) u32 {
return @as(u32, self.BytesPerSector) * self.SectorsPerCluster;
}
};
pub const FsInfo = extern struct {
Signature1: u32 align(1),
Reserved1: [480]u8,
Signature2: u32 align(1),
FreeClusterCount: u32 align(1),
NextFreeCluster: u32 align(1),
Reserved2: [12]u8,
Signature3: u32 align(1),
pub fn isValid(self: *const FsInfo) bool {
return self.Signature1 == constants.magic.FSINFO_SIGNATURE_1 and
self.Signature2 == constants.magic.FSINFO_SIGNATURE_2 and
self.Signature3 == constants.magic.FSINFO_SIGNATURE_3;
}
};
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