1 files changed, 77 insertions, 0 deletions
diff --git a/common/memsize.c b/common/memsize.c
new file mode 100644
index 0000000..dbc812d
--- /dev/null
+++ b/common/memsize.c
@@ -0,0 +1,77 @@
+/*
+ * (C) Copyright 2004
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+
+/*
+ * Check memory range for valid RAM. A simple memory test determines
+ * the actually available RAM size between addresses `base' and
+ * `base + maxsize'.
+ */
+long get_ram_size(volatile long *base, long maxsize)
+{
+	volatile long *addr;
+	long           save[32];
+	long           cnt;
+	long           val;
+	long           size;
+	int            i = 0;
+
+	for (cnt = (maxsize / sizeof (long)) >> 1; cnt > 0; cnt >>= 1) {
+		addr = base + cnt;	/* pointer arith! */
+		save[i++] = *addr;
+		*addr = ~cnt;
+	}
+
+	addr = base;
+	save[i] = *addr;
+	*addr = 0;
+
+	if ((val = *addr) != 0) {
+		/* Restore the original data before leaving the function.
+		 */
+		*addr = save[i];
+		for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
+			addr  = base + cnt;
+			*addr = save[--i];
+		}
+		return (0);
+	}
+
+	for (cnt = 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
+		addr = base + cnt;	/* pointer arith! */
+		val = *addr;
+		*addr = save[--i];
+		if (val != ~cnt) {
+			size = cnt * sizeof (long);
+			/* Restore the original data before leaving the function.
+			 */
+			for (cnt <<= 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
+				addr  = base + cnt;
+				*addr = save[--i];
+			}
+			return (size);
+		}
+	}
+
+	return (maxsize);
+}