Intial revision

lang/cem/libcc.ansi/stdlib/malloc/phys.c

@@ -0,0 +1,96 @@
+/* $Header$ */
+/*
+ * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
+ * See the copyright notice in the ACK home directory, in the file "Copyright".
+ */
+#include	<stdlib.h>
+#include	"param.h"
+#include	"impl.h"
+#include	"check.h"
+#include	"phys.h"
+
+/*	Physical manipulations.
+	The blocks concerned are not in any logical chain.
+*/
+
+public mallink *
+create_chunk(void *p, size_t n)
+{
+	/*	The newly acquired piece of memory at p, of length n,
+		is turned into a free chunk, properly chained in the
+		physical chain.
+		The address of the chunk is returned.
+	*/
+	register mallink *ml;
+	/*	All of malloc memory is followed by a virtual chunk, the
+		mallink of which starts mallink_size() bytes past the last
+		byte in memory.
+		Its use is prevented by testing for ml == ml_last first.
+	*/
+	register mallink *last = ml_last;
+	
+	assert(!last || p == (char *)phys_next_of(last) - mallink_size());
+	ml = (mallink *)((char *)p + mallink_size());	/* bump ml */
+	new_mallink(ml);
+	started_working_on(ml);
+	set_free(ml, 1);
+	set_phys_prev(ml, last);
+	ml_last = ml;
+
+	set_phys_next(ml, (mallink *)((char *)ml + n));
+	calc_checksum(ml);
+	assert(size_of(ml) + mallink_size() == n);
+	if (last && free_of(last)) {
+		coalesce_backw(ml, last);
+		ml = last;
+	}
+	check_mallinks("create_chunk, phys. linked");
+	return ml;
+}
+
+public
+truncate(register mallink *ml, size_t size)
+{
+	/*	The chunk ml is truncated.
+		The chunk at ml is split in two.
+		The remaining part is then freed.
+	*/
+	register mallink *new = (mallink *)((char *)ml + size);
+	register mallink *ph_next = phys_next_of(ml);
+
+	new_mallink(new);
+	set_free(new, 1);
+	set_phys_prev(new, ml);
+	set_phys_next(new, ph_next);
+	calc_checksum(new);
+	if (! last_mallink(ml))	{
+		set_phys_prev(ph_next, new);
+		calc_checksum(ph_next);
+		if (free_of(ph_next)) coalesce_forw(new, ph_next);
+	}
+	else	ml_last = new;
+	set_phys_next(ml, new);
+	calc_checksum(ml);
+
+	started_working_on(new);
+	link_free_chunk(new);
+	stopped_working_on(new);
+	check_mallinks("truncate");
+}
+
+public
+combine_chunks(register mallink *ml1, register mallink *ml2)
+{
+	/*	The chunks ml1 and ml2 are combined.
+	*/
+	register mallink *ml3 = phys_next_of(ml2);
+
+	set_phys_next(ml1, ml3);
+	calc_checksum(ml1);
+	if (!last_mallink(ml2))	{
+		set_phys_prev(ml3, ml1);
+		calc_checksum(ml3);
+	}
+	if (ml_last == ml2)
+		ml_last = ml1;
+}