small improvements for LOAD command and IEC routines

c64/kernal/chkin.s

@@ -1,3 +1,19 @@
 ; Function defined on pp272-273 of C64 Programmers Reference Guide
+
 chkin:
+
+	;; Implemented according to 'C64 Programmers Reference Guide', page 277
+
+	;; First retrieve the FAT/LAT/SAT table index (and check if file is open)
+
+	; txa
+	; jsr find_fls
+	; bcs kernalerror_FILE_NOT_OPEN
+
+	;; Now we have table index in Y - check if file is open for reading
+
+	;; XXX continue implementation
+
 	rts
+
+

c64/kernal/chkout.s

@@ -1,3 +1,17 @@
 ; Function defined on pp272-273 of C64 Programmers Reference Guide
+
 chkout:
+
+	;; Implemented according to 'C64 Programmers Reference Guide', page 278
+
+	;; First retrieve the FAT/LAT/SAT table index (and check if file is open)
+
+	; txa
+	; jsr find_fls
+	; bcs kernalerror_FILE_NOT_OPEN
+
+	;; Now we have table index in Y - check if file is open for writing
+
+	;; XXX continue implementation
+
 	rts

c64/kernal/close.s

@@ -4,19 +4,14 @@ close:
 	;; Implemented accorging to 'C64 Programmers Reference Guide', page 281
 
 	;; XXX this needs more testing (opening 10 files at once, closing in various orders, etc) once the code is more mature
-	
+
 	;; Find the LAT / SAT / FAT entry which LAT corresponds to A
-	
-	ldy LDTND
-	beq close_error_not_found ; table empty
-*
-	dey
-	bmi close_error_not_found ; no more entries
-	cmp LAT, y
-	bne - ; does not match, try the next one
-	
+
+	jsr find_fls
+	bcs close_error_not_found ;; XXX can we report error in IOSTATUS here?
+
 	;; We have the entry index in Y
-	
+
 	;; XXX some devices (like IEC) needs special support here, to free their internal resources!
 	;; Just make sure the Y register value is kept, or redo ldy DFTLN
 *
@@ -33,9 +28,9 @@ close:
 *
 	;; Decrement the list size variable
 	dec LDTND
-	;; FALLTHROUGH (for now) - success
-	
+
+	;; FALLTHROUGH - success
+
 close_error_not_found:
-	
-	;; XXX it seems that this function can't report errors, am I right?
+
 	rts

c64/kernal/findfls.s

@@ -0,0 +1,23 @@
+
+;; Just a helper routine
+
+;; Find the LAT / SAT / FAT entry index where LAT corresponds to A, returns index in Y
+;; Carry flag set means not found
+
+find_fls:
+
+	ldy LDTND
+	beq find_fls_not_found ; table empty
+*
+	dey
+	bmi find_fls_not_found ; no more entries
+	cmp LAT, y
+	bne - ; does not match, try the next one
+	
+	clc
+	rts
+
+find_fls_not_found:
+
+	sec
+	rts

c64/kernal/load.s

@@ -54,9 +54,6 @@ print_filename_loop:
 	iny
 	jmp print_filename_loop
 *
-	lda #$0d
-	jsr JCHROUT
-
 	;; XXX - Use default device number
 	;; http://www.zimmers.net/anonftp/pub/cbm/programming/serial-bus.pdf
 	;; p13, 16.
@@ -145,11 +142,11 @@ sent_filename:
 	lda kernal_load_or_verify_flag
 	beq +
 	jsr printf
-	.byte "VERIFYING", 0
+	.byte $0D, "VERIFYING", 0
 	jmp load_print_start_addr
 *
 	jsr printf
-	.byte "LOADING", 0
+	.byte $0D, "LOADING", 0
 load_print_start_addr:
 	jsr printf
 	.byte " FROM $",0
@@ -223,9 +220,8 @@ load_done:
 	;; Set IEC status back to idle
 	jsr iec_set_idle
 
-	;; Return last address written to +1
-	;; (Even though Compute's Mapping the 64 says without the +1.
-	;; I'm suspicious. Will have to check behavour on an original C64)
+	;; Return last address - Compute's Mapping the 64 says without the '+1',
+	;; checked on original ROMs that this is really the case
 	ldx load_save_start_ptr+0
 	ldy load_save_start_ptr+1