Added a pfs_remove() function and a pfs_seek() stub to the Commodore platforms.

- "Normalized" some Assembly code.
- Implemented CFS_APPEND in pfs_open().
- Made CFS_WRITE work in VICE's virtual disk/file system.

platform/c64/lib/pfs_remove.S

@@ -0,0 +1,59 @@
+;
+; Copyright (c) 2016, Greg King
+; All rights reserved.
+;
+; Redistribution and use in source and binary forms, with or without
+; modification, are permitted provided that the following conditions
+; are met:
+; 1. Redistributions of source code must retain the above copyright
+;    notice, this list of conditions, and the following disclaimer.
+; 2. Redistributions in binary form must reproduce the above copyright
+;    notice, this list of conditions, and the following disclaimer in the
+;    documentation and/or other materials provided with the distribution.
+; 3. Neither the name of the author nor the names of contributors
+;    may be used to endorse or promote products derived from this software
+;    without specific prior written permission.
+;
+; THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS"; AND,
+; ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+; ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+; OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+; HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+; OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+; SUCH DAMAGE.
+;
+; This file is part of the Contiki operating system.
+;
+; Author: Greg King <gregdk@users.sf.net>
+;
+;---------------------------------------------------------------------
+	.importzp	ptr2
+	.import		addysp
+	.import		pfs_makename, pfs_scratch
+
+	.export		_pfs_remove
+;---------------------------------------------------------------------
+MAXLEN	=	80		; max. filename length
+
+FNL	:=	$B7		; filename length
+;---------------------------------------------------------------------
+.proc	_pfs_remove
+	asl	ptr2		; force pfs_makename to format for pfs_scratch
+	jsr	pfs_makename
+	ldx	FNL
+	beq	error		; no name
+
+	jsr	pfs_scratch
+	ldx	#>$0000
+	bcs	error
+ret:	txa
+	ldy	#MAXLEN + 8	; free filename space
+	jmp	addysp
+
+error:	dex			;(ldx #>-1)
+	bne	ret
+.endproc