BACKTRACK support: PCjs can now report which portions of which files are being read into memory
This commit is contained in:
Jeff Parsons
jeffpar
parent
aaebc5856e
commit
197392bce9
5 changed files with 407 additions and 155 deletions
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@ -86,40 +86,126 @@ DiskAPI.DISKETTE_FORMATS = {
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2949120: [80,2,36] // media type 0xF0: 80 cylinders, 2 heads (double-sided), 36 sectors/track, (5760 total sectors x 512 bytes/sector == 2949120)
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};
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DiskAPI.MBR = {
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PARTITIONS: {
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OFFSET: 0x1BE,
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ENTRY: {
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STATUS: 0x00, // 0x80 if active
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CHS_FIRST: 0x01, // 3-byte CHS specifier
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TYPE: 0x04, // see TYPE.*
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CHS_LAST: 0x05, // 3-byte CHS specifier
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LBA_FIRST: 0x08,
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LBA_TOTAL: 0x0C,
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LENGTH: 0x10
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},
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STATUS: {
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ACTIVE: 0x80
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},
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TYPE: {
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EMPTY: 0x00,
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FAT12_PRIMARY: 0x01, // DOS 2.0 and up (12-bit FAT)
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FAT16_PRIMARY: 0x04 // DOS 3.0 and up (16-bit FAT)
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}
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},
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SIG_OFFSET: 0x1FE,
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SIGNATURE: 0xAA55 // to be clear, the low byte (at offset 0x1FE) is 0x55 and the high byte (at offset 0x1FF) is 0xAA
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};
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/*
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* BIOS Parameter Block (BPB) offsets in DOS-compatible boot sectors
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* Boot sector offsets (and assorted constants) in DOS-compatible boot sectors (DOS 2.0 and up)
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*
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* WARNING: I've heard apocryphal stories about SIGNATURE being improperly reversed on some systems
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* (ie, 0x55AA instead 0xAA55) -- perhaps by a dyslexic programmer -- so be careful out there.
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*/
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DiskAPI.BOOT = {
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JMP_OPCODE: 0x000, // 1 byte for a JMP opcode, followed by a 1 or 2-byte offset
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OEM_STRING: 0x003, // 8 bytes
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SIG_OFFSET: 0x1FE,
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SIGNATURE: 0xAA55 // to be clear, the low byte (at offset 0x1FE) is 0x55 and the high byte (at offset 0x1FF) is 0xAA
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};
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/*
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* BIOS Parameter Block (BPB) offsets in DOS-compatible boot sectors (DOS 2.0 and up)
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*/
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DiskAPI.BPB = {
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JMP_OPCODE: 0x00, // 1 byte for a JMP opcode, followed by a 1 or 2-byte offset
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OEM_STRING: 0x03, // 8 bytes
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SECTOR_BYTES: 0x0B, // 2 bytes: bytes per sector (eg, 0x200 or 512)
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CLUSTER_SECS: 0x0D, // 1 byte: sectors per cluster (eg, 1)
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RESERVED_SECS: 0x0E, // 2 bytes: reserved sectors; ie, # sectors preceding the first FAT--usually just the boot sector (eg, 1)
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FAT_TOTAL: 0x10, // 1 byte: FAT copies (eg, 2)
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ROOT_ENTRIES: 0x11, // 2 bytes: root directory entries (eg, 0x40 or 64) 0x40 * 0x20 = 0x800 (1 sector is 0x200 bytes, total of 4 sectors)
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TOTAL_SECS: 0x13, // 2 bytes: number of sectors (eg, 0x140 or 320); if zero, refer to LARGE_SECS
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MEDIA_TYPE: 0x15, // 1 byte: media type (eg, 0xFF: 320Kb, 0xFE: 160Kb, 0xFD: 360Kb, 0xFC: 180Kb)
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FAT_SECS: 0x16, // 2 bytes: sectors per FAT (eg, 1)
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TRACK_SECS: 0x18, // 2 bytes: sectors per track (eg, 8)
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HEAD_TOTAL: 0x1A, // 2 bytes: number of heads (eg, 1)
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HIDDEN_SECS: 0x1C, // 4 bytes: number of hidden sectors (always 0 for non-partitioned media)
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LARGE_SECS: 0x20 // 4 bytes: number of sectors if TOTAL_SECS is zero
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SECTOR_BYTES: 0x00B, // 2 bytes: bytes per sector (eg, 0x200 or 512)
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CLUSTER_SECS: 0x00D, // 1 byte: sectors per cluster (eg, 1)
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RESERVED_SECS: 0x00E, // 2 bytes: reserved sectors; ie, # sectors preceding the first FAT--usually just the boot sector (eg, 1)
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TOTAL_FATS: 0x010, // 1 byte: FAT copies (eg, 2)
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ROOT_DIRENTS: 0x011, // 2 bytes: root directory entries (eg, 0x40 or 64) 0x40 * 0x20 = 0x800 (1 sector is 0x200 bytes, total of 4 sectors)
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TOTAL_SECS: 0x013, // 2 bytes: number of sectors (eg, 0x140 or 320); if zero, refer to LARGE_SECS
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MEDIA_TYPE: 0x015, // 1 byte: media type (see DiskAPI.FAT.MEDIA_*)
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FAT_SECS: 0x016, // 2 bytes: sectors per FAT (eg, 1)
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TRACK_SECS: 0x018, // 2 bytes: sectors per track (eg, 8)
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TOTAL_HEADS: 0x01A, // 2 bytes: number of heads (eg, 1)
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HIDDEN_SECS: 0x01C, // 4 bytes: number of hidden sectors (always 0 for non-partitioned media)
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LARGE_SECS: 0x020 // 4 bytes: number of sectors if TOTAL_SECS is zero
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};
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/*
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* Directory Entry offsets in FAT-based disk images
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* Media descriptor bytes for DOS-compatible FAT-formatted disks (stored in the first byte of the FAT)
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*/
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DiskAPI.DIR = {
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NAME: 0x00, // 8 bytes
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EXT: 0x08, // 3 bytes
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ATTR: 0x0B, // 1 byte
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MODTIME: 0x16, // 2 bytes
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MODDATE: 0x18, // 2 bytes
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CLUSTER: 0x1A, // 2 bytes
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SIZE: 0x1C, // 4 bytes (typically zero for subdirectories)
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LENGTH: 0x20 // 32 bytes total
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DiskAPI.FAT = {
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MEDIA_160KB: 0xFE, // 5.25-inch, 1-sided, 8-sector, 40-track
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MEDIA_180KB: 0xFC, // 5.25-inch, 1-sided, 9-sector, 40-track
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MEDIA_320KB: 0xFF, // 5.25-inch, 2-sided, 8-sector, 40-track
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MEDIA_360KB: 0xFD, // 5.25-inch, 2-sided, 9-sector, 40-track
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MEDIA_720KB: 0xF9, // 3.5-inch, 2-sided, 9-sector, 80-track
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MEDIA_1200KB: 0xF9, // 3.5-inch, 2-sided, 15-sector, 80-track
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MEDIA_1440KB: 0xF0, // 3.5-inch, 2-sided, 18-sector, 80-track
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MEDIA_2880KB: 0xF0 // 3.5-inch, 2-sided, 36-sector, 80-track
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};
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/*
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* Cluster constants for 12-bit FATs (CLUSNUM_FREE, CLUSNUM_RES and CLUSNUM_MIN are the same for all FATs)
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*/
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DiskAPI.FAT12 = {
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MAX_CLUSTERS: 4084,
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CLUSNUM_FREE: 0, // this should NEVER appear in cluster chain (except at the start of an empty chain)
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CLUSNUM_RES: 1, // reserved; this should NEVER appear in cluster chain
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CLUSNUM_MIN: 2, // smallest valid cluster number
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CLUSNUM_MAX: 0xFF6, // largest valid cluster number
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CLUSNUM_BAD: 0xFF7, // bad cluster; this should NEVER appear in cluster chain
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CLUSNUM_EOC: 0xFF8 // end of chain (actually, anything from 0xFF8-0xFFF indicates EOC)
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};
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/*
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* Cluster constants for 16-bit FATs (CLUSNUM_FREE, CLUSNUM_RES and CLUSNUM_MIN are the same for all FATs)
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*/
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DiskAPI.FAT16 = {
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MAX_CLUSTERS: 65524,
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CLUSNUM_FREE: 0, // this should NEVER appear in cluster chain (except at the start of an empty chain)
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CLUSNUM_RES: 1, // reserved; this should NEVER appear in cluster chain
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CLUSNUM_MIN: 2, // smallest valid cluster number
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CLUSNUM_MAX: 0xFFF6, // largest valid cluster number
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CLUSNUM_BAD: 0xFFF7, // bad cluster; this should NEVER appear in cluster chain
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CLUSNUM_EOC: 0xFFF8 // end of chain (actually, anything from 0xFFF8-0xFFFF indicates EOC)
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};
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/*
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* Directory Entry offsets (and assorted constants) in FAT disk images
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*
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* NOTE: Versions of DOS prior to 2.0 use INVALID exclusively to mark available directory entries; any entry marked
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* UNUSED will actually be considered USED. In DOS 2.0 and up, UNUSED was added to indicate that all remaining entries
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* are unused, relieving it from having to initialize the rest of the sectors in the directory cluster(s). And in fact,
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* you WILL encounter garbage in subsequent directory sectors if you attempt to read past an UNUSED entry.
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*/
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DiskAPI.DIRENT = {
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NAME: 0x000, // 8 bytes
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EXT: 0x008, // 3 bytes
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ATTR: 0x00B, // 1 byte
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MODTIME: 0x016, // 2 bytes
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MODDATE: 0x018, // 2 bytes
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CLUSTER: 0x01A, // 2 bytes
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SIZE: 0x01C, // 4 bytes (typically zero for subdirectories)
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LENGTH: 0x20, // 32 bytes total
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UNUSED: 0x00, // indicates this and all subsequent directory entries are unused
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INVALID: 0xE5 // indicates this directory entry is unused
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};
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/*
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* Possible values for DIRENT.ATTR
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*/
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DiskAPI.ATTR = {
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READONLY: 0x01, // PC-DOS 2.0 and up
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HIDDEN: 0x02,
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