blob: 1c3a141a7fcab0812ac1af31a033be2a4e1c4501 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
//! FAT32 Cluster Operations
const constants = @import("shared").fat32.constants;
const errors = @import("shared").fat32.errors;
const ClusterError = errors.cluster.ClusterError;
pub fn isValidCluster(cluster: u32) bool {
return cluster >= constants.clusters.CLUSTER_DATA_START and
cluster < constants.clusters.CLUSTER_EOC_START and
cluster != constants.clusters.CLUSTER_BAD;
}
pub fn isEndOfChain(cluster: u32) bool {
return (cluster & constants.clusters.CLUSTER_MASK) >= constants.clusters.CLUSTER_EOC_START;
}
pub fn getFatPosition(cluster: u32, bytes_per_sector: u32) struct { Sector: u32, Offset: u32 } {
const fat_offset = cluster * @sizeOf(u32);
return .{
.Sector = fat_offset / bytes_per_sector,
.Offset = fat_offset % bytes_per_sector,
};
}
pub fn clusterToLba(
cluster: u32,
data_start_lba: u64,
sectors_per_cluster: u32,
) u64 {
return data_start_lba + (@as(u64, cluster - constants.clusters.CLUSTER_DATA_START) * sectors_per_cluster);
}
pub fn parseFatEntry(entry: u32) ClusterError!?u32 {
const next = entry & constants.clusters.CLUSTER_MASK;
if (isEndOfChain(next)) {
return null;
}
if (next == constants.clusters.CLUSTER_BAD) {
return ClusterError.BadCluster;
}
if (next < constants.clusters.CLUSTER_DATA_START) {
return ClusterError.InvalidCluster;
}
return next;
}
|
