home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Amiga Format 106
/
af106sub.adf
/
datatypes.LZX
/
anim_datatype
/
ASYNCIO.C
< prev
next >
Wrap
C/C++ Source or Header
|
1983-01-16
|
17KB
|
514 lines
/*
**
** $VER: asyncio.c 1.10 (4.8.97)
** anim.datatype 1.10
**
** Async I/O for anim.datatype
**
** Written 1996/97 by Roland 'Gizzy' Mainz
** Based on asyncio.c by Martin Tailefer from 3.1_Examples1:AsyncIO/asyncio.h
**
*/
/* project includes */
#include "classbase.h"
#include "asyncio.h"
#define D( x )
/*****************************************************************************/
/* this macro lets us long-align structures on the stack */
#define D_S(type,name) char a_##name[sizeof(type)+3]; \
type *name = (type *)((LONG)(a_##name+3) & ~3);
/*****************************************************************************/
/* send out an async packet to the file system. */
static
void SendPacket( struct ClassBase *cb, struct AsyncFile *file, APTR arg2 )
{
D( kprintf( "send packet\n" ) );
file -> af_Packet . sp_Pkt . dp_Port = &file -> af_PacketPort;
file -> af_Packet . sp_Pkt . dp_Arg2 = (LONG)arg2;
PutMsg( (file -> af_Handler), (&(file -> af_Packet . sp_Msg)) );
file -> af_PacketPending = TRUE;
}
/*****************************************************************************/
/* this function waits for a packet to come back from the file system. If no
* packet is pending, state from the previous packet is returned. This ensures
* that once an error occurs, it state is maintained for the rest of the life
* of the file handle.
*
* This function also deals with IO errors, bringing up the needed DOS
* requesters to let the user retry an operation or cancel it.
*/
static
LONG WaitPacket( struct ClassBase *cb, struct AsyncFile *file )
{
LONG bytes;
D( kprintf( "wait packet\n" ) );
if( file -> af_PacketPending )
{
while( TRUE )
{
/* This enables signalling when a packet comes back to the port */
file -> af_PacketPort . mp_SigTask = FindTask( NULL );
file -> af_PacketPort . mp_Flags = PA_SIGNAL;
/* Wait for the packet to come back, and remove it from the message
* list. Since we know no other packets can come in to the port, we can
* safely use Remove() instead of GetMsg(). If other packets could come in,
* we would have to use GetMsg(), which correctly arbitrates access in such
* a case
*/
Remove( (struct Node *)WaitPort( (&(file -> af_PacketPort)) ) );
/* set the port type back to PA_IGNORE so we won't be bothered with spurious signals */
file -> af_PacketPort . mp_Flags = PA_IGNORE;
/* mark packet as no longer pending since we removed it */
file -> af_PacketPending = FALSE;
bytes = file -> af_Packet . sp_Pkt . dp_Res1;
if( bytes >= 0 )
{
D( kprintf( "wait packet success \n" ) );
/* packet didn't report an error, so bye... */
return( bytes );
}
/* see if the user wants to try again... */
if( ErrorReport( (file -> af_Packet . sp_Pkt . dp_Res2), REPORT_STREAM, (file -> af_File), NULL ) )
return( -1 );
/* user wants to try again, resend the packet */
SendPacket( cb, file, (file -> af_Buffers[ file -> af_CurrentBuf ]) );
}
}
/* last packet's error code, or 0 if packet was never sent */
SetIoErr( file -> af_Packet . sp_Pkt . dp_Res2 );
D( kprintf( "wait packet success (%ld)\n", (file -> af_Packet . sp_Pkt . dp_Res1) ) );
return( file -> af_Packet . sp_Pkt . dp_Res1 );
}
/*****************************************************************************/
/* this function puts the packet back on the message list of our
* message port.
*/
static
void RequeuePacket( struct ClassBase *cb, struct AsyncFile *file )
{
D( kprintf( "RequeuePacket\n" ) );
AddHead( &file -> af_PacketPort . mp_MsgList, &file -> af_Packet . sp_Msg . mn_Node );
file -> af_PacketPending = TRUE;
}
/*****************************************************************************/
/* this function records a failure from a synchronous DOS call into the
* packet so that it gets picked up by the other IO routines in this module
*/
static
void RecordSyncFailure( struct ClassBase *cb, struct AsyncFile *file )
{
D( kprintf( "RecordSyncFailure\n" ) );
file -> af_Packet . sp_Pkt . dp_Res1 = -1;
file -> af_Packet . sp_Pkt . dp_Res2 = IoErr();
}
/*****************************************************************************/
struct AsyncFile *OpenAsync( struct ClassBase *cb, BPTR handle, LONG bufferSize )
{
struct AsyncFile *file;
struct FileHandle *fh;
BPTR lock;
LONG blockSize;
D_S( struct InfoData, infoData );
file = NULL;
if( handle )
{
lock = DupLockFromFH( handle );
/* if it was possible to obtain a lock on the same device as the
* file we're working on, get the block size of that device and
* round up our buffer size to be a multiple of the block size.
* This maximizes DMA efficiency.
*/
blockSize = 512;
if( lock )
{
if( Info( lock, infoData ) )
{
blockSize = infoData -> id_BytesPerBlock;
bufferSize = (((bufferSize + (blockSize * 2) - 1) / (blockSize * 2)) * (blockSize * 2));
}
UnLock( lock );
}
else
{
D( kprintf( "DupLockFromDH failed\n" ) );
}
/* now allocate the ASyncFile structure, as well as the read buffers.
* Add 15 bytes to the total size in order to allow for later
* quad-longword alignement of the buffers
*/
if( file = (struct AsyncFile *)AllocVec( (sizeof( struct AsyncFile ) + bufferSize + 15UL), MEMF_PUBLIC ) )
{
file -> af_File = handle;
file -> af_BlockSize = blockSize;
/* initialize the struct ASyncFile structure. We do as much as we can here,
* in order to avoid doing it in more critical sections
*
* Note how the two buffers used are quad-longword aligned. This
* helps performance on 68040 systems with copyback cache. Aligning
* the data avoids a nasty side-effect of the 040 caches on DMA.
* Not aligning the data causes the device driver to have to do
* some magic to avoid the cache problem. This magic will generally
* involve flushing the CPU caches. This is very costly on an 040.
* Aligning things avoids the need for magic, at the cost of at
* most 15 bytes of ram.
*/
fh = BADDR(file->af_File);
file->af_Handler = fh->fh_Type;
file->af_BufferSize = bufferSize / 2;
file->af_Buffers[0] = (APTR)(((ULONG)file + sizeof(struct AsyncFile) + 15) & 0xfffffff0);
file->af_Buffers[1] = (APTR)((ULONG)file->af_Buffers[0] + file->af_BufferSize);
file->af_Offset = file->af_Buffers[0];
file->af_CurrentBuf = 0;
file->af_SeekOffset = 0;
file->af_PacketPending = FALSE;
/* this is the port used to get the packets we send out back.
* It is initialized to PA_IGNORE, which means that no signal is
* generated when a message comes in to the port. The signal bit
* number is initialized to SIGB_SINGLE, which is the special bit
* that can be used for one-shot signalling. The signal will never
* be set, since the port is of type PA_IGNORE. We'll change the
* type of the port later on to PA_SIGNAL whenever we need to wait
* for a message to come in.
*
* The trick used here avoids the need to allocate an extra signal
* bit for the port. It is quite efficient.
*/
file->af_PacketPort.mp_MsgList.lh_Head = (struct Node *)&file->af_PacketPort.mp_MsgList.lh_Tail;
file->af_PacketPort.mp_MsgList.lh_Tail = NULL;
file->af_PacketPort.mp_MsgList.lh_TailPred = (struct Node *)&file->af_PacketPort.mp_MsgList.lh_Head;
file->af_PacketPort.mp_Node.ln_Type = NT_MSGPORT;
file->af_PacketPort.mp_Flags = PA_IGNORE;
file->af_PacketPort.mp_SigBit = SIGB_SINGLE;
file->af_PacketPort.mp_SigTask = FindTask( NULL );
file->af_Packet.sp_Pkt.dp_Link = &file->af_Packet.sp_Msg;
file->af_Packet.sp_Pkt.dp_Arg1 = fh->fh_Arg1;
file->af_Packet.sp_Pkt.dp_Arg3 = file->af_BufferSize;
file->af_Packet.sp_Pkt.dp_Res1 = 0;
file->af_Packet.sp_Pkt.dp_Res2 = 0;
file->af_Packet.sp_Msg.mn_Node.ln_Name = (STRPTR)&file->af_Packet.sp_Pkt;
file->af_Packet.sp_Msg.mn_Node.ln_Type = NT_MESSAGE;
file->af_Packet.sp_Msg.mn_Length = sizeof(struct StandardPacket);
/* if we are in read mode, send out the first read packet to
* the file system. While the application is getting ready to
* read data, the file system will happily fill in this buffer
* with DMA transfers, so that by the time the application
* needs the data, it will be in the buffer waiting
*/
file->af_Packet.sp_Pkt.dp_Type = ACTION_READ;
file->af_BytesLeft = 0;
#if 0
if (file->af_Handler)
SendPacket(cb, file,file->af_Buffers[0]);
#endif
}
else
{
Close( handle );
}
}
return( file );
}
/*****************************************************************************/
LONG CloseAsync( struct ClassBase *cb, struct AsyncFile *file)
{
LONG result;
if (file)
{
result = WaitPacket(cb, file);
Close( file -> af_File );
FreeVec( file );
}
else
{
SetIoErr( ERROR_INVALID_LOCK );
result = -1;
}
return( result );
}
/*****************************************************************************/
LONG ReadAsync( struct ClassBase *cb, struct AsyncFile *file, APTR buffer, LONG numBytes )
{
LONG totalBytes;
LONG bytesArrived;
totalBytes = 0;
/* if we need more bytes than there are in the current buffer, enter the read loop */
while( numBytes > (file -> af_BytesLeft) )
{
/* drain buffer */
CopyMem( file -> af_Offset, buffer, file -> af_BytesLeft );
numBytes -= file->af_BytesLeft;
buffer = (APTR)((ULONG)buffer + file->af_BytesLeft);
totalBytes += file->af_BytesLeft;
file->af_BytesLeft = 0;
bytesArrived = WaitPacket( cb, file );
if( bytesArrived <= 0 )
{
if( bytesArrived == 0 )
return(totalBytes);
return(-1);
}
/* ask that the buffer be filled */
SendPacket( cb, file, file -> af_Buffers[ 1 - file -> af_CurrentBuf ] );
if (file->af_SeekOffset > bytesArrived)
file->af_SeekOffset = bytesArrived;
file->af_Offset = (APTR)((ULONG)file->af_Buffers[file->af_CurrentBuf] + file->af_SeekOffset);
file->af_CurrentBuf = 1 - file->af_CurrentBuf;
file->af_BytesLeft = bytesArrived - file->af_SeekOffset;
file->af_SeekOffset = 0;
}
CopyMem(file->af_Offset,buffer,numBytes);
file->af_BytesLeft -= numBytes;
file->af_Offset = (APTR)((ULONG)file->af_Offset + numBytes);
return (totalBytes + numBytes);
}
/*****************************************************************************/
LONG ReadCharAsync(struct ClassBase *cb, struct AsyncFile *file)
{
unsigned char ch;
if (file->af_BytesLeft)
{
/* if there is at least a byte left in the current buffer, get it
* directly. Also update all counters
*/
ch = *(char *)file->af_Offset;
file->af_BytesLeft--;
file->af_Offset = (APTR)((ULONG)file->af_Offset + 1);
return((LONG)ch);
}
/* there were no characters in the current buffer, so call the main read
* routine. This has the effect of sending a request to the file system to
* have the current buffer refilled. After that request is done, the
* character is extracted for the alternate buffer, which at that point
* becomes the "current" buffer
*/
if( ReadAsync( cb, file, &ch, 1 ) > 0 )
return((LONG)ch);
/* We couldn't read above, so fail */
return( -1 );
}
/*****************************************************************************/
LONG SeekAsync( struct ClassBase *cb, struct AsyncFile *file, LONG position, LONG mode )
{
LONG current,
target;
LONG minBuf,
maxBuf;
LONG bytesArrived;
LONG diff;
LONG filePos;
LONG roundTarget;
D( kprintf( "SeekAsync\n" ) );
bytesArrived = WaitPacket( cb, file );
if( bytesArrived < 0 )
return( -1 );
/* figure out what the actual file position is */
filePos = Seek( file -> af_File, 0, OFFSET_CURRENT );
if( filePos < 0 )
{
RecordSyncFailure( cb, file );
return( -1 );
}
/* figure out what the caller's file position is */
current = filePos - (file->af_BytesLeft+bytesArrived) + file->af_SeekOffset;
file->af_SeekOffset = 0;
/* figure out the absolute offset within the file where we must seek to */
if( mode == OFFSET_CURRENT )
{
target = current + position;
}
else if (mode == OFFSET_BEGINNING)
{
target = position;
}
else /* if (mode == OFFSET_END) */
{
D_S( struct FileInfoBlock, fib );
if (!ExamineFH(file->af_File,fib))
{
RecordSyncFailure(cb, file);
return(-1);
}
target = fib->fib_Size + position;
}
/* figure out what range of the file is currently in our buffers */
minBuf = current - (LONG)((ULONG)file->af_Offset - (ULONG)file->af_Buffers[file->af_CurrentBuf]);
maxBuf = current + file->af_BytesLeft + bytesArrived; /* WARNING: this is one too big */
diff = target - current;
if ((target < minBuf) || (target >= maxBuf))
{
/* the target seek location isn't currently in our buffers, so
* move the actual file pointer to the desired location, and then
* restart the async read thing...
*/
/* this is to keep our file reading block-aligned on the device.
* block-aligned reads are generally quite a bit faster, so it is
* worth the trouble to keep things aligned
*/
roundTarget = (target / file->af_BlockSize) * file->af_BlockSize;
if (Seek(file->af_File,roundTarget-filePos,OFFSET_CURRENT) < 0)
{
RecordSyncFailure(cb, file);
return(-1);
}
SendPacket(cb, file,file->af_Buffers[0]);
file->af_SeekOffset = target-roundTarget;
file->af_BytesLeft = 0;
file->af_CurrentBuf = 0;
file->af_Offset = file->af_Buffers[0];
}
else if ((target < current) || (diff <= file->af_BytesLeft))
{
/* one of the two following things is true:
*
* 1. The target seek location is within the current read buffer,
* but before the current location within the buffer. Move back
* within the buffer and pretend we never got the pending packet,
* just to make life easier, and faster, in the read routine.
*
* 2. The target seek location is ahead within the current
* read buffer. Advance to that location. As above, pretend to
* have never received the pending packet.
*/
RequeuePacket(cb, file);
file->af_BytesLeft -= diff;
file->af_Offset = (APTR)((ULONG)file->af_Offset + diff);
}
else
{
/* at this point, we know the target seek location is within
* the buffer filled in by the packet that we just received
* at the start of this function. Throw away all the bytes in the
* current buffer, send a packet out to get the async thing going
* again, readjust buffer pointers to the seek location, and return
* with a grin on your face... :-)
*/
diff -= file->af_BytesLeft;
SendPacket(cb, file,file->af_Buffers[file->af_CurrentBuf]);
file->af_Offset = (APTR)((ULONG)file->af_Buffers[file->af_CurrentBuf] + diff);
file->af_BytesLeft = bytesArrived - diff;
}
return( current );
}