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//! AFS cluster operations
const endian = @import("../../utils/bytes/endian.zig");
const fs = @import("../../common/constants/fs.zig");
pub fn is_valid(cluster: u32) bool {
return cluster >= fs.CLUSTER_MIN and cluster < fs.CLUSTER_END;
}
pub fn to_lba(afs: anytype, cluster: u32) u64 {
return afs.partition_offset + afs.data_area_sector + (cluster - fs.CLUSTER_MIN);
}
pub fn get_next(afs: anytype, cluster: u32) !u32 {
const entry_offset = cluster * 4;
const table_sector = afs.partition_offset + afs.alloc_table_sector + (entry_offset / afs.bytes_per_sector);
const offset = entry_offset % afs.bytes_per_sector;
var sector: [fs.SECTOR_SIZE]u8 align(fs.SECTOR_ALIGN) = undefined;
if (!afs.device.read_sector(table_sector, §or)) {
return error.ReadFailed;
}
return endian.read_u32_le(sector[offset..]);
}
pub fn write_alloc(afs: anytype, cluster: u32, value: u32) !void {
const entry_offset = cluster * 4;
const table_sector = afs.partition_offset + afs.alloc_table_sector + (entry_offset / afs.bytes_per_sector);
const offset = entry_offset % afs.bytes_per_sector;
var sector: [fs.SECTOR_SIZE]u8 align(fs.SECTOR_ALIGN) = undefined;
if (!afs.device.read_sector(table_sector, §or)) {
return error.ReadFailed;
}
endian.write_u32_le(sector[offset..], value);
if (!afs.device.write_sector(table_sector, §or)) {
return error.WriteFailed;
}
}
pub fn allocate(afs: anytype) !u32 {
var cluster: u32 = fs.CLUSTER_MIN;
while (cluster < afs.total_clusters) : (cluster += 1) {
const entry_offset = cluster * 4;
const table_sector = afs.partition_offset + afs.alloc_table_sector + (entry_offset / afs.bytes_per_sector);
const offset = entry_offset % afs.bytes_per_sector;
var sector: [fs.SECTOR_SIZE]u8 align(fs.SECTOR_ALIGN) = undefined;
if (!afs.device.read_sector(table_sector, §or)) {
return error.ReadFailed;
}
if (endian.read_u32_le(sector[offset..]) == fs.CLUSTER_FREE) {
try write_alloc(afs, cluster, fs.CLUSTER_END);
afs.increment_used();
return cluster;
}
}
return error.DiskFull;
}
pub fn free(afs: anytype, cluster: u32) !void {
try write_alloc(afs, cluster, fs.CLUSTER_FREE);
afs.decrement_used();
}
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