Add some definitions for FAT32 file system

Adds some struct types for the FAT32 file system.

This just includes the information in the parameter blocks, not any
actual files.

sw/fat.h

@@ -0,0 +1,42 @@
+#ifndef _FAT_H
+#define _FAT_H
+
+#include <stdint.h>
+
+typedef struct {
+    uint16_t bytes_per_sector;
+    uint8_t sectors_per_cluster;
+    uint16_t reserved_sectors;
+    uint8_t fat_count;
+    uint16_t max_dir_entries;
+    uint16_t total_sector_count;
+    uint8_t media_descriptor;
+    uint16_t sectors_per_fat;
+} dos_2_bpb_t;
+
+typedef struct {
+    dos_2_bpb_t bpb2;
+    uint16_t sectors_per_track;
+    uint16_t head_count;
+    uint32_t hidden_sector_count;
+    uint32_t logical_sector_count;
+    uint32_t sectors_per_fat;
+    uint16_t extended_flags;
+    uint16_t version;
+    uint32_t root_cluster;
+    uint16_t system_information;
+    uint16_t backup_boot_sector;
+    uint8_t reserved[12];
+} dos_3_bpb_t;
+
+typedef struct {
+    dos_3_bpb_t bpb3;
+    uint8_t drive_num;
+    uint8_t reserved;
+    uint8_t extended_signature;
+    uint32_t volume_id;
+    uint8_t partition_label[11];
+    uint8_t filesystem_type[8];
+} ebpb_t;
+
+#endif