Merge from trunk.

plat/msdos386/libsys/build.lua

@@ -1,6 +1,7 @@
 acklibrary {
     name = "lib",
     srcs = {
+		"./rename.s",
 --		"./brk.c",
 --		"./close.s",
 --		"./creat.c",

plat/msdos86/libsys/build.lua

@@ -6,6 +6,7 @@ acklibrary {
 		"./getpid.s",
 		"./_hol0.s",
 		"./isatty.s",
+		"./rename.s",
 		"./sys_exists.s",
 		"./sys_getdate.s",
 		"./sys_gettime.s",

plat/msdos86/libsys/rename.s

@@ -0,0 +1,26 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Rename a file.
+
+.define _rename
+_rename:
+	mov bx, sp
+	push di
+	mov dx, 2(bx)
+	mov di, 4(bx)
+	movb ah, 0x56
+	int 0x21
+	pop di
+	jmp .sys_zret