452 lines
10 KiB
C
452 lines
10 KiB
C
/* Double-buffered write.
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*
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* 2/11/07
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* - cut from im_generate
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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/*
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#define DEBUG
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <assert.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/types.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif /*HAVE_UNISTD_H*/
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#include <vips/vips.h>
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#include <vips/internal.h>
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#include <vips/thread.h>
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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC*/
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/* A buffer we are going to write to disc in a background thread.
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*/
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typedef struct _WriteBuffer {
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im_threadgroup_t *tg; /* What makes the pixels */
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REGION *region; /* Pixels */
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Rect area; /* Part of image this region covers */
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im_semaphore_t go; /* Start bg thread loop */
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im_semaphore_t nwrite; /* Number of threads writing to region */
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im_semaphore_t done; /* Bg thread has done write */
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int write_errno; /* Save write errors here */
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GThread *thread; /* BG writer thread */
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gboolean kill; /* Set to ask thread to exit */
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im_wbuffer_fn write_fn; /* BG write with this */
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void *a; /* Client data */
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void *b;
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} WriteBuffer;
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/* A write function for VIPS images. Just write() the pixel data.
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*/
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int
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im_wbuffer_write_vips( REGION *region, Rect *area, void *a, void *b )
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{
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size_t nwritten, count;
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void *buf;
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count = region->bpl * area->height;
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buf = IM_REGION_ADDR( region, 0, area->top );
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do {
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nwritten = write( region->im->fd, buf, count );
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/* Write failed? Note in wbuffer errno for the main
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* thread to pick up.
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*/
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if( nwritten == (size_t) -1 )
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return( errno );
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buf = (void *) ((char *) buf + nwritten);
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count -= nwritten;
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} while( count > 0 );
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return( 0 );
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}
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static void
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wbuffer_free( WriteBuffer *wbuffer )
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{
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/* Is there a thread running this region? Kill it!
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*/
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if( wbuffer->thread ) {
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wbuffer->kill = TRUE;
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im_semaphore_up( &wbuffer->go );
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/* Return value is always NULL (see wbuffer_write_thread).
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*/
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(void) g_thread_join( wbuffer->thread );
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#ifdef DEBUG_CREATE
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printf( "wbuffer_free: g_thread_join()\n" );
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#endif /*DEBUG_CREATE*/
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wbuffer->thread = NULL;
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}
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IM_FREEF( im_region_free, wbuffer->region );
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im_semaphore_destroy( &wbuffer->go );
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im_semaphore_destroy( &wbuffer->nwrite );
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im_semaphore_destroy( &wbuffer->done );
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im_free( wbuffer );
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}
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static void
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wbuffer_write( WriteBuffer *wbuffer )
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{
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wbuffer->write_errno = wbuffer->write_fn( wbuffer->region,
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&wbuffer->area, wbuffer->a, wbuffer->b );
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#ifdef DEBUG
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printf( "wbuffer_write: %d bytes from wbuffer %p\n",
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region->bpl * area->height, wbuffer );
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#endif /*DEBUG*/
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}
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#ifdef HAVE_THREADS
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/* Run this as a thread to do a BG write.
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*/
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static void *
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wbuffer_write_thread( void *data )
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{
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WriteBuffer *wbuffer = (WriteBuffer *) data;
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for(;;) {
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im_semaphore_down( &wbuffer->go );
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if( wbuffer->kill )
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break;
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/* Wait for all writer threads to leave this wbuffer.
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*/
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im_semaphore_downn( &wbuffer->nwrite, 0 );
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wbuffer_write( wbuffer );
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/* Signal write complete.
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*/
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im_semaphore_up( &wbuffer->done );
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}
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return( NULL );
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}
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#endif /*HAVE_THREADS*/
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static WriteBuffer *
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wbuffer_new( im_threadgroup_t *tg, im_wbuffer_fn write_fn, void *a, void *b )
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{
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WriteBuffer *wbuffer;
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if( !(wbuffer = IM_NEW( NULL, WriteBuffer )) )
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return( NULL );
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wbuffer->tg = tg;
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wbuffer->region = NULL;
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im_semaphore_init( &wbuffer->go, 0, "go" );
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im_semaphore_init( &wbuffer->nwrite, 0, "nwrite" );
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im_semaphore_init( &wbuffer->done, 0, "done" );
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wbuffer->write_errno = 0;
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wbuffer->thread = NULL;
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wbuffer->kill = FALSE;
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wbuffer->write_fn = write_fn;
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wbuffer->a = a;
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wbuffer->b = b;
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if( !(wbuffer->region = im_region_create( tg->im )) ) {
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wbuffer_free( wbuffer );
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return( NULL );
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}
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#ifdef HAVE_THREADS
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/* Make this last (picks up parts of wbuffer on startup).
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*/
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if( !(wbuffer->thread = g_thread_create( wbuffer_write_thread, wbuffer,
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TRUE, NULL )) ) {
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im_error( "wbuffer_new", _( "unable to create thread" ) );
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wbuffer_free( wbuffer );
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return( NULL );
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}
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#endif /*HAVE_THREADS*/
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return( wbuffer );
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}
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/* At end of work_fn ... need to tell wbuffer write thread that we're done.
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*/
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static int
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wbuffer_work_fn( REGION *region, WriteBuffer *wbuffer )
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{
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im_semaphore_upn( &wbuffer->nwrite, 1 );
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return( 0 );
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}
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/* Attach a wbuffer to a position.
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*/
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static int
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wbuffer_position( WriteBuffer *wbuffer,
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int left, int top, int width, int height )
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{
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Rect image, area;
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image.left = 0;
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image.top = 0;
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image.width = wbuffer->tg->im->Xsize;
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image.height = wbuffer->tg->im->Ysize;
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area.left = left;
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area.top = top;
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area.width = width;
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area.height = height;
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im_rect_intersectrect( &area, &image, &wbuffer->area );
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if( im_region_buffer( wbuffer->region, &wbuffer->area ) )
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return( -1 );
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/* This should be an exclusive buffer, hopefully.
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*/
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assert( !wbuffer->region->buffer->done );
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return( 0 );
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}
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/* Loop over a wbuffer filling it threadily.
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*/
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static int
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wbuffer_fill( WriteBuffer *wbuffer )
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{
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Rect *area = &wbuffer->area;
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im_threadgroup_t *tg = wbuffer->tg;
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IMAGE *im = tg->im;
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Rect image;
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int x, y;
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#ifdef DEBUG
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printf( "wbuffer_fill: starting for wbuffer %p at line %d\n",
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wbuffer, area->top );
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#endif /*DEBUG*/
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image.left = 0;
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image.top = 0;
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image.width = im->Xsize;
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image.height = im->Ysize;
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/* Loop over area, sparking threads for all sub-parts in turn.
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*/
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for( y = area->top; y < IM_RECT_BOTTOM( area ); y += tg->ph )
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for( x = area->left; x < IM_RECT_RIGHT( area ); x += tg->pw ) {
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im_thread_t *thr;
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Rect pos;
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Rect clipped;
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/* thrs appear on idle when the child thread does
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* threadgroup_idle_add and hits the 'go' semaphore.
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*/
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thr = im_threadgroup_get( tg );
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/* Set the position we want to generate with this
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* thread. Clip against the size of the image and the
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* space available in or.
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*/
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pos.left = x;
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pos.top = y;
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pos.width = tg->pw;
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pos.height = tg->ph;
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im_rect_intersectrect( &pos, &image, &clipped );
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im_rect_intersectrect( &clipped, area, &clipped );
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/* Note params.
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*/
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thr->oreg = wbuffer->region;
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thr->pos = clipped;
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thr->x = clipped.left;
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thr->y = clipped.top;
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thr->a = wbuffer;
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#ifdef DEBUG
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printf( "wbuffer_fill: starting for tile at %d x %d\n",
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x, y );
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#endif /*DEBUG*/
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/* Add writer to n of writers on wbuffer, set it going.
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*/
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im_semaphore_upn( &wbuffer->nwrite, -1 );
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im_threadgroup_trigger( thr );
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/* Trigger any eval callbacks on our source image.
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*/
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im__handle_eval( tg->im, tg->pw, tg->ph );
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/* Check for errors.
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*/
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if( im_threadgroup_iserror( tg ) ) {
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/* Don't kill threads yet ... we may want to
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* get some error stuff out of them.
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*/
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im_threadgroup_wait( tg );
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return( -1 );
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}
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}
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return( 0 );
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}
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/* Eval to file.
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*/
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static int
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wbuffer_eval_to_file( WriteBuffer *b1, WriteBuffer *b2 )
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{
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im_threadgroup_t *tg = b1->tg;
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IMAGE *im = tg->im;
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int y;
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assert( b1->tg == b2->tg );
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#ifdef DEBUG
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int nstrips;
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nstrips = 0;
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printf( "wbuffer_eval_to_file: partial image output to file\n" );
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#endif /*DEBUG*/
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/* Note we'll be working to fill a contigious area.
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*/
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tg->inplace = 1;
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/* What threads do at the end of each tile ... decrement the nwrite
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* semaphore.
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*/
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tg->work = (im__work_fn) wbuffer_work_fn;
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/* Fill to in steps, write each to the output.
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*/
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for( y = 0; y < im->Ysize; y += tg->nlines ) {
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/* Attach to this position in image.
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*/
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if( wbuffer_position( b1, 0, y, im->Xsize, tg->nlines ) )
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return( -1 );
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/* Spark off threads to fill with data.
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*/
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if( wbuffer_fill( b1 ) )
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return( -1 );
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/* We have to keep the ordering on wbuffer writes, so we can't
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* have more than one background write going at once. Plus we
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* want to make sure write()s don't get interleaved. Wait for
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* the previous BG write (if any) to finish.
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*/
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if( y > 0 ) {
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im_semaphore_down( &b2->done );
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/* Previous write suceeded?
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*/
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if( b2->write_errno ) {
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im_error_system( b2->write_errno,
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"im__eval_to_file",
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_( "write failed" ) );
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return( -1 );
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}
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}
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/* b1 write can go.
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*/
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im_semaphore_up( &b1->go );
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#ifndef HAVE_THREADS
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/* No threading ... just write.
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*/
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wbuffer_write( b1 );
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#endif /*HAVE_THREADS*/
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/* Rotate wbuffers.
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*/
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{
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WriteBuffer *t;
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t = b1; b1 = b2; b2 = t;
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}
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#ifdef DEBUG
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nstrips++;
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#endif /*DEBUG*/
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}
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/* Wait for all threads to finish, check for any errors.
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*/
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im_threadgroup_wait( tg );
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im_semaphore_down( &b2->done );
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if( im_threadgroup_iserror( tg ) )
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return( -1 );
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if( b1->write_errno || b2->write_errno ) {
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im_error_system(
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b1->write_errno ? b1->write_errno : b2->write_errno,
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"im__eval_to_file", _( "write failed" ) );
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return( -1 );
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}
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#ifdef DEBUG
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printf( "wbuffer_eval_to_file: success! %d strips written\n", nstrips );
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#endif /*DEBUG*/
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return( 0 );
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}
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int
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im_wbuffer( im_threadgroup_t *tg,
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im_wbuffer_fn write_fn, void *a, void *b )
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{
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WriteBuffer *b1, *b2;
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b1 = wbuffer_new( tg, write_fn, a, b );
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b2 = wbuffer_new( tg, write_fn, a, b );
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if( !b1 || !b2 || wbuffer_eval_to_file( b1, b2 ) ) {
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IM_FREEF( wbuffer_free, b1 );
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IM_FREEF( wbuffer_free, b2 );
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return( -1 );
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}
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wbuffer_free( b1 );
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wbuffer_free( b2 );
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return( 0 );
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}
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