1 files changed, 114 insertions, 0 deletions
diff --git a/editor/specialty/pbmlife.c b/editor/specialty/pbmlife.c
new file mode 100644
index 00000000..be34cc69
--- /dev/null
+++ b/editor/specialty/pbmlife.c
@@ -0,0 +1,114 @@
+/* pbmlife.c - read a portable bitmap and apply Conway's rules of Life to it
+**
+** Copyright (C) 1988,1 1991 by Jef Poskanzer.
+**
+** Permission to use, copy, modify, and distribute this software and its
+** documentation for any purpose and without fee is hereby granted, provided
+** that the above copyright notice appear in all copies and that both that
+** copyright notice and this permission notice appear in supporting
+** documentation.  This software is provided "as is" without express or
+** implied warranty.
+*/
+
+#include "pbm.h"
+
+int
+main( argc, argv )
+int argc;
+char* argv[];
+    {
+    FILE* ifp;
+    bit* prevrow;
+    bit* thisrow;
+    bit* nextrow;
+    bit* temprow;
+    register bit* newrow;
+    int rows, cols, row;
+    register int col, count;
+    int format;
+
+
+    pbm_init( &argc, argv );
+
+    if ( argc > 2 )
+	pm_usage( "[pbmfile]" );
+
+    if ( argc == 2 )
+	ifp = pm_openr( argv[1] );
+    else
+	ifp = stdin;
+
+    pbm_readpbminit( ifp, &cols, &rows, &format );
+    prevrow = pbm_allocrow( cols );
+    thisrow = pbm_allocrow( cols );
+    nextrow = pbm_allocrow( cols );
+
+    pbm_writepbminit( stdout, cols, rows, 0 );
+    newrow = pbm_allocrow( cols );
+
+    pbm_readpbmrow( ifp, nextrow, cols, format );
+
+    for ( row = 0; row < rows; ++row )
+	{
+	temprow = prevrow;
+	prevrow = thisrow;
+	thisrow = nextrow;
+	nextrow = temprow;
+	if ( row < rows - 1 )
+	    pbm_readpbmrow( ifp, nextrow, cols, format );
+
+        for ( col = 0; col < cols; ++col )
+	    {
+	    /* Check the neighborhood, with an unrolled double loop. */
+	    count = 0;
+	    if ( row > 0 )
+		{
+		/* upper left */
+		if ( col > 0 && prevrow[col - 1] == PBM_WHITE )
+		    ++count;
+		/* upper center */
+		if ( prevrow[col] == PBM_WHITE )
+		    ++count;
+		/* upper right */
+		if ( col < cols - 1 && prevrow[col + 1] == PBM_WHITE )
+		    ++count;
+		}
+	    /* left */
+	    if ( col > 0 && thisrow[col - 1] == PBM_WHITE )
+		++count;
+	    /* right */
+	    if ( col < cols - 1 && thisrow[col + 1] == PBM_WHITE )
+		++count;
+	    if ( row < rows - 1 )
+		{
+		/* lower left */
+		if ( col > 0 && nextrow[col - 1] == PBM_WHITE )
+		    ++count;
+		/* lower center */
+		if ( nextrow[col] == PBM_WHITE )
+		    ++count;
+		/* lower right */
+		if ( col < cols - 1 && nextrow[col + 1] == PBM_WHITE )
+		    ++count;
+		}
+
+	    /* And compute the new value. */
+	    if ( thisrow[col] == PBM_WHITE )
+		if ( count == 2 || count == 3 )
+		    newrow[col] = PBM_WHITE;
+		else
+		    newrow[col] = PBM_BLACK;
+	    else
+		if ( count == 3 )
+		    newrow[col] = PBM_WHITE;
+		else
+		    newrow[col] = PBM_BLACK;
+	    }
+	pbm_writepbmrow( stdout, newrow, cols, 0 );
+	}
+
+    pm_close( ifp );
+    pm_close( stdout );
+
+    exit( 0 );
+    }