aos/devices/fat_bpb.dev
Daniel Schwyn 6d444bf552 Main handout
Signed-off-by: Daniel Schwyn <daniel.schwyn@inf.ethz.ch>
2022-03-03 14:57:51 +01:00

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/*
* Copyright (c) 2011, ETH Zurich. All rights reserved.
*
* This file is distributed under the terms in the attached LICENSE file.
* If you do not find this file, copies can be found by writing to:
* ETH Zurich D-INFK, Universitaetstrasse 6, CH-8092 Zurich. Attn: Systems Group.
*/
/*
* fat16_bootsector.dev
*
* DESCRIPTION: FAT16 file system boot sector.
*
* This always starts at offset 0xb and is documented as such in Microsoft
* documentation [1], so put the first entry at offset 0xb too, allowing the
* initialize function to be called with the regular base address.
*
* [1] http://support.microsoft.com/kb/140418
*/
device fat_bpb msbfirst (addr b) "FAT BIOS Parameter Block (BPB)" {
register bps rw addr(b,0x0b) "Bytes per sector (must be 512, 1024, 2048 or 4096)" type(uint16);
register spc rw addr(b,0x0d) "Sectors per cluster, must be power of 2" type(uint8);
register rsvs rw addr(b,0x0e) "Reserved sectors from the start of the volume" type(uint16);
register fatc rw addr(b,0x10) "Number of FAT copies" type(uint8);
register rtc rw addr(b,0x11) "Maximum number of root entries" type(uint16);
register ssc rw addr(b,0x13) "Small sector count, used when volume is smaller than 32 MB" type(uint16);
register mdes rw addr(b,0x15) "Media descriptor" type(uint8);
register spf rw addr(b,0x16) "Sectors per FAT" type(uint16);
register spt rw addr(b,0x18) "Sectors per track" type(uint16);
register heds rw addr(b,0x1a) "Number of heads" type(uint16);
register hids rw addr(b,0x1c) "Hidden sectors (preceding volume start)" type(uint32);
register lsc rw addr(b,0x20) "Large sector count, when volume is larger than 32 MB" type(uint32);
};