Moved reusable parts of remove into oserrcheck.

Rewrote remove().
Added rename().


git-svn-id: svn://svn.cc65.org/cc65/trunk@2272 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/common/oserrcheck.s

@@ -0,0 +1,35 @@
+;
+; Ullrich von Bassewitz, 2003-08-12
+;
+; Helper function for several high level file functions.
+;
+; The function will store the value in A into _oserror. If the value is not
+; zero, it is translated into a standard error number which is then stored
+; into errno, and -1 is returned in a/x. If the value in A was zero, errno
+; is not changed, and zero is returned in a/x.
+;
+
+        .export         oserrcheck
+        .import         __oserror
+        .import         __osmaperrno
+        .import         __errno
+
+.proc   oserrcheck
+
+        sta     __oserror               ; Store the error code
+        tay                             ; Did we have an error?
+        beq     ok                      ; Branch if no
+        jsr     __osmaperrno            ; Map os error into errno code
+        sta     __errno
+        stx     __errno+1               ; Save in errno
+        lda     #$FF                    ; Return -1
+
+; Error free, A contains zero
+
+ok:     tax                             ; Make high byte also zero
+        rts
+
+.endproc
+
+
+