This is a documentation of the changes to the SWI interface to FileCore made between version 2.04 and 2.05.
FileCore_DiscOp
Extended reason code, Write Track (4)
On entry
R1 = &000000o4
R2 = Disc address of start of track
R3 = 0 (this distinguishes it from a normal Write track)
R4 = Pointer to disc format structure
On exit
All regs preserved, except in an error.
The disc format structure is as follows:
Offset Length Meaning
0 4 Sector size (bytes)
4 4 Gap1 side 0
8 4 Gap1 side 1
12 4 Gap3
16 1 Sectors per track
17 1 Density:
1 - single (125Kbps FM)
2 - double (250Kbps MFM)
3 - Double+ (300Kbps MFM)
4 - quad (500Kbps MFM)
8 - octal (1000Mbps MFM)
18 1 Options:
Bit 0 1 - index mark required
Bit 1 1 - double step
Bit 2-3 0 - alternate sides
1 - Format side 1 only
2 - format side 2 only
3 - Sequence sides
Bit 4-7 reserved, should be 0
19 1 Sector fill value
20 4 cylinders per drive
24 12 Reserved, should be 0
36 ? Sector ID buffer, 1 word per sector:
bits use
0-7 Cylinder number mod 256
8-15 Head (0 for side 1, 1 for side 2)
16-23 Sector number
24-31 Log2 sector size - 7, eg 1 for 256 byte sector
The o nibble in R1 is the flags nibble as normal. The SWI will format a track of the specified disc. An error will occur if the specified format is not possible to generate, or if the track requested is outside the valid range. The tracks are numbered from 0, so the valid track numbers are 0 to number of track minus one. The mapping of the address is controlled by the disc structure record.
New reason code, CachedReadSectors (9)
In
R1 = 9 (CachedReadSectors)
R2 = disc address
R3 = pointer to buffer
R4 = length in bytes
R6 = Cache handle
R8 = Pointer to FileCore instance private word
Out
R1 preserved
R2 = disc address of next byte to be transfered
R3 = pointer to next buffer location to be transfered
R4 = number of bytes not transfered
R6 = New cache handle
This DiscOp reason code will read sectors via a cache held in the RMA. To start a sequence of these operations call this with R6=0. The following options apply when this reason is used:
An alternate defect list cannot be specified
A scatter list can not be specified
Escape can not be ignored
A 1 second timeout on floppy discs applies
Setting these options bits will have no effect. Multiple calls to this may update R6, the cache handle. The new value of R6 must be used in subsequent calls of CachedReadSectors. To discard the cache once finished call FileCore_DiscardReadSectorsCache.
FileCore_Create
Notes on the PRM:
In the desciptor block the flag bits have the following meanings:
Bit Meaning when set
0 Winnie needs FIQ
1 Floppy needs FIQ
2 Unused (The PRM incorrectly described this bit)
3 Use scratch space only when a temporary buffer is needed
(The PRM did not describe this bit). Other areas
which are sometimes used are:
Spare screen memory
Wimp free pool
RMA heap
System heap
Application area
Dir cache
Here is a table of usage:
Area: SS VDU WF RH SH AA DC
Usage:
Rename * * * * *
Close * * * * *
EnsureSize * * * * *
AllocCompact * * * * *
Compact * * * * *
*Backup X X * * * *
*backup X Y * * * * *
*backup X X q * * * * *
*backup X Y q * * * * * *
*compact * * * * *
Key:
SS Scratch space
VDU Spare screen area
WF Wimp free pool
RH RMA heap
SH System heap
AA Application area
DC Directory cache
Rename fsfunc_Rename
Close fsentry_Close
EnsureSize fsargs_EnsureSize
AllocCompact Auto-compact triggered when allocating space for a file
Compact Auto-compact
*backup The *Backup command
*Compact The *Compact command
4 Winnies support mount like floppies do, ie they fill in sector size,
heads, sectors per track and density.
5 Winnies support poll change. This means the poll change call on a
winnie will work and return a sensible value. This also means that
locking winnies will have a sensible result.
FileCore_DiscardReadSectorsCache (&40546)
In
R6 = Cache handle
Out
Cache discarded
FileCore_DiscFormat (&40547)
In
R0 = pointer to the disc format structure to be filled in (64 bytes)
R1 = number of SWI to vet the format
R2 = parameter to pass to the vetting SWI
R3 = format specifier
Out
regs preserved
This SWI fills in the format structure with the parameters for the specified format. Once filled in the format structure will be vetted by the given SWI before this SWI returns. The following format specifiers are defined:
&80 L format floppy
&81 D format floppy
&82 E format floppy
&83 F format floppy
FileCore_LayoutStructure (&40548)
In
R0 = identifier of particular format to lay out
R1 = pointer to bad block list
R2 = pointer to nul-terminated disc name
R3 = file handle
Out
Regs preserved
This SWI will lay out into the specified file a set of structures corresponding to the identified format. The format identifier is a pointer to a disc record. An error will be returned if the specified format can not map out defects and there were defects in the defect list.
FileCore_MiscOp
In
R0 = reason
R1 = drive
R2..R5 depend on reason
R8 = pointer to FileCore instance private word
Out
R0..R6 depend on reason
This SWI provides various miscellaneous functions for accessing drives:
Misc_Mount
In
R0 = 0
R1 = drive
R2 = disc address to read from
R3 = pointer to buffer
R4 = length to read into buffer
R5 = pointer to disc record to fill in
Out
R0..R5 preserved
This will mount the disc in the specified drive and fill in, where possible, the physical details of the disc in the supplied disc record. The disc record need only be 32 bytes long.
Misc_PollChanged
In
R0 = 1
R1 = drive
R2 = sequence number
Out
R2 = new sequence number
R3 = result flags
This will sence the status of the drive. The sequence number is used to prevent a user of Misc_PollChanged missing a change of disc in the drive. The bits in the resul flags have the following meanings:
Bit Meaning when set 0 Disc hasn't changed since last poll 1 Disc may have changed since last poll 2 Disc changed since last poll 3 Drive is empty 4 Drive is ready 5 Drive is 40-track 6 Drive has empty detection 7 Drive has disc changed detection 8 Disc in drive is high density 9 Disc density detection works 10 Drive ready works11-31 Reserved for future use - will be 0. Only one of bits 0-3 will be set at any time. To use this quote a sequence number of 0 first time round and quote back the returned sequence number from the last poll in each further poll.
Misc_LockDrive
In
R0 = 2
R1 = drive
Out
-
This locks the disc in the drive. For floppy discs this causes the drive light to remain illuminated until the drive is unlocked. Note that locks are counted so that each LockDrive must be matched by an UnlockDrive.
Misc_UnlockDrive
In
R0 = 3
R1 = drive
Out
-
This reverses the LockDrive miscellaneous operation.
Misc_PollPeriod
In
R0 = 4
R1 = drive
Out
R5 = minimum polling period (in centi-seconds), or -1 if disc changed
doesn't work.
R6 = pointer to media type string eg 'disc' for ADFS.