Initial import of the CDE 2.1.30 sources from the Open Group.

cde/lib/tt/mini_isam/isindfreel.c

@@ -0,0 +1,112 @@
+/*%%  (c) Copyright 1993, 1994 Hewlett-Packard Company			 */
+/*%%  (c) Copyright 1993, 1994 International Business Machines Corp.	 */
+/*%%  (c) Copyright 1993, 1994 Sun Microsystems, Inc.			 */
+/*%%  (c) Copyright 1993, 1994 Novell, Inc. 				 */
+/*%%  $XConsortium: isindfreel.c /main/3 1995/10/23 11:41:03 rswiston $ 			 				 */
+#ifndef lint
+static char sccsid[] = "@(#)isindfreel.c 1.3 89/07/17 Copyr 1988 Sun Micro";
+#endif
+
+/*
+ * Copyright (c) 1988 by Sun Microsystems, Inc.
+ */
+
+/*
+ * isfreelist.c
+ *
+ * Description:
+ *	Free list maintenance functions
+ */
+
+#include "isam_impl.h"
+
+extern Bufhdr *_isdisk_fix();
+
+/*
+ * blkno = _isfreel_alloc()
+ *
+ * Allocate a new index page.
+ */
+
+Blkno 
+_isindfreel_alloc(fcb)
+    Fcb			*fcb;
+{
+    Bufhdr		*pbhdr;
+    char		*p;
+    int			npointers;
+    Blkno		blkno;
+
+    if (fcb->indfreelist == FREELIST_NOPAGE) {
+
+	/* 
+	 * We must write something to the buffer, or we will get 
+	 * segmentation fault when using mapped I/O.
+	 */
+	fcb->indsize = _extend_file(fcb, fcb->indfd, fcb->indsize);
+
+	return (fcb->indsize - 1);
+    }
+
+    pbhdr = _isdisk_fix(fcb, fcb->indfd, fcb->indfreelist, ISFIXWRITE);
+    p = pbhdr->isb_buffer;
+    
+    npointers = ldshort(p + FL_NPOINTERS_OFF);
+    
+    if (npointers > 0) {
+	blkno = ldblkno(p + FL_POINTERS_OFF + npointers * BLKNOSIZE);
+	npointers--;
+	stshort((short)npointers, p + FL_NPOINTERS_OFF);
+	
+	return (ldblkno(p + FL_POINTERS_OFF + npointers * BLKNOSIZE));
+    }
+    else {
+	blkno = fcb->indfreelist;
+	fcb->indfreelist = ldblkno(p + FL_NEXT_OFF);
+	
+	return (blkno);
+    }
+}
+
+/*
+ * _isfreel_free()
+ *
+ * Free an index page.
+ */
+
+void
+_isindfreel_free(fcb, blkno)
+    Fcb			*fcb;
+    Blkno		blkno;
+{
+    Bufhdr		*pbhdr;
+    char		*p;
+    int			npointers;
+
+    if (fcb->indfreelist != FREELIST_NOPAGE) {
+	pbhdr = _isdisk_fix(fcb, fcb->indfd, fcb->indfreelist, ISFIXWRITE);
+	p = pbhdr->isb_buffer;
+
+	npointers = ldshort(p + FL_NPOINTERS_OFF);
+	
+	if (npointers < FL_MAXNPOINTERS) {
+	    stblkno(blkno, p + FL_POINTERS_OFF + npointers * BLKNOSIZE);
+	    npointers++;
+	    stshort((short)npointers, p + FL_NPOINTERS_OFF);
+
+	    return;
+	}
+    }
+
+
+    pbhdr = _isdisk_fix(fcb, fcb->indfd, blkno, ISFIXWRITE);
+    p = pbhdr->isb_buffer;
+    
+    /* Mark page to indicate that it is in the free list. */
+    stshort((short)PT_FREELIST, p + FL_TYPE_OFF);
+
+    stshort((short)0, p + FL_NPOINTERS_OFF);
+    stblkno(fcb->indfreelist, p + FL_NEXT_OFF);
+
+    fcb->indfreelist = blkno;
+}