Rewrote cbm_open and cbm_read in assembler saving about 80 bytes total.

git-svn-id: svn://svn.cc65.org/cc65/trunk@1318 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/cbm/cbm_open.s

@@ -0,0 +1,44 @@
+;
+; Ullrich von Bassewitz, 22.06.2002
+;
+; Original C code by Marc 'BlackJack' Rintsch, 18.03.2001
+;
+; unsigned char __fastcall__ cbm_open (unsigned char lfn,
+;                                      unsigned char device,
+;                                      unsigned char sec_addr,
+;                                      const char* name);
+; /* Opens a file. Works just like the BASIC command.
+;  * Returns 0 if opening was successful, otherwise an errorcode (see table
+;  * below).
+;  */
+; {
+;     cbm_k_setlfs(lfn, device, sec_addr);
+;     cbm_k_setnam(name);
+;     return _oserror = cbm_k_open();
+; }
+;
+
+       	.export	       	_cbm_open
+	.import		popa
+        .import         _cbm_k_setlfs, _cbm_k_setnam, _cbm_k_open
+        .import         __oserror
+
+_cbm_open:
+        pha
+        txa
+        pha                     ; Save name
+
+        jsr     popa            ; Get sec_addr
+        jsr     _cbm_k_setlfs   ; Call SETLFS, pop all args
+
+        pla
+        tax
+        pla                     ; Get name
+        jsr     _cbm_k_setnam
+
+        jsr     _cbm_k_open
+        sta     __oserror
+
+        rts
+
+