tomwalters@0: /*
tomwalters@0:     pullable.c
tomwalters@0:     ==========
tomwalters@0: 
tomwalters@0:     sources who's native operation is receive pull commands.
tomwalters@0: 
tomwalters@0: */
tomwalters@0: 
tomwalters@0: #include "stitch.h"
tomwalters@0: #include "source.h"
tomwalters@0: 
tomwalters@0: #ifndef  lint
tomwalters@0: static char *sccs_id = "@(#)pullable.c	1.3 John Holdsworth (MRC-APU) 6/6/91" ;
tomwalters@0: #endif
tomwalters@0: 
tomwalters@0: #if 0
tomwalters@0: #define DEBUG 1
tomwalters@0: #endif
tomwalters@0: 
tomwalters@0: /*
tomwalters@0:     fill a users buffer from a process that returns it's own buffer
tomwalters@0: 
tomwalters@0: */
tomwalters@0: 
tomwalters@0: static Pointer fillFromPullable( source, bytes, buffer )
tomwalters@0: struct _pullable_source *source ;
tomwalters@0: ByteCount *bytes ;
tomwalters@0: Pointer buffer ;
tomwalters@0: {
tomwalters@0:     Pointer input = source->parent.pull( source, bytes ) ;
tomwalters@0: 
tomwalters@0:     CopyArray( (char *) input, (char *) buffer, *bytes ) ;
tomwalters@0: 
tomwalters@0:     return ( buffer ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: Source setPullableSource( source, puller, name )
tomwalters@0: struct _pullable_source *source ;
tomwalters@0: Pointer (*puller)() ;
tomwalters@0: char *name ;
tomwalters@0: {
tomwalters@0:     return ( SetSource( source, puller, fillFromPullable, nonRoller, name ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: Pointer deletePullableSource( source )
tomwalters@0: struct _pullable_source *source ;
tomwalters@0: {
tomwalters@0:     return ( DeleteSource( source ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: /*
tomwalters@0:     simple slave source as example of derived source
tomwalters@0: 
tomwalters@0: */
tomwalters@0: 
tomwalters@0: typedef struct { struct _pullable_source parent ; Source master ; } *SlaveSource ;
tomwalters@0: 
tomwalters@0: static Pointer slavePull( source, bytes )
tomwalters@0: SlaveSource source ;
tomwalters@0: ByteCount *bytes ;
tomwalters@0: {
tomwalters@0:     register int last = *bytes == 0 ;
tomwalters@0: 
tomwalters@0:     if( !last )
tomwalters@0: 	return ( _SPTR( source->master )->returned ) ;
tomwalters@0:     else
tomwalters@0: 	return ( DeletePullableSource( source ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: Source newSlaveSource( master )
tomwalters@0: Source master ;
tomwalters@0: {
tomwalters@0:     DeclareNew( SlaveSource, source ) ;
tomwalters@0: 
tomwalters@0:     source->master = master ;
tomwalters@0: 
tomwalters@0:     return ( SetPullableSource( source, slavePull, "pullable.c slave" ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: /*
tomwalters@0:     the simplest Source is one direct from memory
tomwalters@0: 
tomwalters@0: */
tomwalters@0: 
tomwalters@0: typedef struct {
tomwalters@0:  struct _pullable_source parent ;
tomwalters@0:  Pointer next ;
tomwalters@0:  } *StaticSource ;
tomwalters@0: 
tomwalters@0: static Pointer staticPull( source, bytes )
tomwalters@0: StaticSource source ;
tomwalters@0: ByteCount *bytes ;
tomwalters@0: {
tomwalters@0:     register int last = *bytes == 0 ;
tomwalters@0:     register Pointer this = source->next ;
tomwalters@0: 
tomwalters@0:     if( !last ) {
tomwalters@0: 
tomwalters@0: 	source->next += abs( *bytes ) ;
tomwalters@0: 
tomwalters@0: 	return ( this ) ;
tomwalters@0:     }
tomwalters@0:     else
tomwalters@0: 	return ( DeletePullableSource( source ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: Source newStaticSource( pointer )
tomwalters@0: Pointer pointer ;
tomwalters@0: {
tomwalters@0:     DeclareNew( StaticSource, source ) ;
tomwalters@0: 
tomwalters@0:     source->next = pointer ;
tomwalters@0: 
tomwalters@0:     return ( SetPullableSource( source, staticPull, "pullable.c static" ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: typedef struct {
tomwalters@0:  struct _pullable_source parent ;
tomwalters@0:  Source input ; Pointer buffer ; ByteCount retained ;
tomwalters@0: } *RetainingSource ;
tomwalters@0: 
tomwalters@0: static Pointer retaining_callback( source, bytes )
tomwalters@0: RetainingSource source ;
tomwalters@0: ByteCount *bytes ;
tomwalters@0: {
tomwalters@0:     register int last = *bytes == 0 ;
tomwalters@0:     Pointer buffer = RollSome( source->input, bytes, source->retained ) ;
tomwalters@0: 
tomwalters@0:     if( !last )
tomwalters@0: 	return ( buffer ) ;
tomwalters@0:     else
tomwalters@0: 	return ( DeletePullableSource( source ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: Source newRetainingSource( input, retained )
tomwalters@0: Source input ;
tomwalters@0: ByteCount retained ;
tomwalters@0: {
tomwalters@0:     DeclareNew( RetainingSource, source ) ;
tomwalters@0: 
tomwalters@0:     source->retained = retained ;
tomwalters@0: 
tomwalters@0:     source->input = NewRollableSource( input ) ;
tomwalters@0: 
tomwalters@0:     return ( SetPullableSource( source, retaining_callback, "pullable.c retaining" ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: typedef struct {
tomwalters@0:  struct _pullable_source parent ;
tomwalters@0:  Source input ; ByteCount delay ;
tomwalters@0:  } *DelayingSource  ;
tomwalters@0: 
tomwalters@0: static Pointer delay_callback( source, bytes )
tomwalters@0: DelayingSource source ;
tomwalters@0: ByteCount *bytes ;
tomwalters@0: {
tomwalters@0:     register int last = *bytes == 0 ;
tomwalters@0:     Pointer delayed = PullSome( source->input, bytes ) - source->delay ;
tomwalters@0: 
tomwalters@0:     if( !last )
tomwalters@0: 	return ( delayed ) ;
tomwalters@0:     else
tomwalters@0: 	return ( DeletePullableSource( source ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: Source newDelayingSource( input, delay )
tomwalters@0: Source input ;
tomwalters@0: ByteCount delay ;
tomwalters@0: {
tomwalters@0:     DeclareNew( DelayingSource, source ) ;
tomwalters@0: 
tomwalters@0:     source->input = NewRetainingSource( input, delay ) ;
tomwalters@0: 
tomwalters@0:     source->delay = delay ;
tomwalters@0: 
tomwalters@0:     return ( SetPullableSource( source, delay_callback, "pullable.c delaying" ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: typedef struct {
tomwalters@0:  struct _pullable_source parent ;
tomwalters@0:  Source input ; Pointer buffer, position, end ; ByteCount segment ;
tomwalters@0: } *BlockingSource ;
tomwalters@0: 
tomwalters@0: static Pointer block_callback( source, bytes )
tomwalters@0: BlockingSource source ;
tomwalters@0: ByteCount *bytes ;
tomwalters@0: {
tomwalters@0:     register int last = *bytes == 0 ;
tomwalters@0:     ByteCount segment = source->segment ;
tomwalters@0: 
tomwalters@0:     if( source->position == source->end || last ) {
tomwalters@0: 
tomwalters@0: 	if( segment < *bytes || last )
tomwalters@0: 	    segment = *bytes ;
tomwalters@0: 
tomwalters@0: 	source->buffer = PullSome( source->input, &segment ) ;
tomwalters@0: #if DEBUG
tomwalters@0: printf( "pulled block at %x from %s\n", source->buffer, SourceName( source->input ) ) ;
tomwalters@0: #endif
tomwalters@0: 	source->end  = source->buffer + segment ;
tomwalters@0: 
tomwalters@0: 	source->position = source->buffer ;
tomwalters@0:     }
tomwalters@0: 
tomwalters@0:     if( *bytes > source->end - source->position )
tomwalters@0: 	*bytes = source->end - source->position ;
tomwalters@0: 
tomwalters@0:     source->position += *bytes ;
tomwalters@0: 
tomwalters@0:     if( !last )
tomwalters@0: 	return ( source->position - *bytes ) ;
tomwalters@0:     else
tomwalters@0: 	return ( DeletePullableSource( source ) ) ;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: Source newBlockingSource( input, segment )
tomwalters@0: Source input ;
tomwalters@0: ByteCount segment ;
tomwalters@0: {
tomwalters@0:     DeclareNew( BlockingSource, source ) ;
tomwalters@0: 
tomwalters@0:     source->input = input ;
tomwalters@0: 
tomwalters@0:     source->position = source->end = (Pointer) 0 ;
tomwalters@0: 
tomwalters@0:     source->segment = segment ;
tomwalters@0: 
tomwalters@0:     return ( SetPullableSource( source, block_callback, "pullable.c blocking" ) ) ;
tomwalters@0: }
tomwalters@0: