implemented CLALL routine, added support for LAT/SAT/FAT and LDTND variables

c64/basic/,aliases.s

@@ -58,6 +58,7 @@
 	.alias BUCKYSTATUS $91
 	.alias load_or_verify_flag $93
 	.alias current_file_num $98
+	.alias LDTND $98 ; number of entries in LAT / FAT / SAT tables
 	.alias DFLTN $99
 	.alias input_device_number DFLTN
 	; bit 6 = error messages, bit 7 = control messages
@@ -74,6 +75,7 @@
 	;; - 'Compute's Mapping the Commodore 64', page 32
 	.alias CMP0 $B0 ;; $B0-$B1
 
+
 	.alias cassette_buffer_ptr $B2
 	.alias current_filename_length $B7
 	.alias current_logical_filenum $B8
@@ -110,6 +112,11 @@
 
 	.alias basic_input_buffer $0200
 	
+	;; Kernal tables for opened files, 10 entries each
+	.alias LAT $0259 ; logical file numbers
+	.alias FAT $0263 ; device numbers
+	.alias SAT $026D ; secondary addresses	
+	
 	; "Compute's Mapping the 64" book
 	.alias keyboard_buffer $0277
 	.alias MEMSTR $0281

c64/kernal/,aliases.s

@@ -9,6 +9,7 @@
 	.alias BUCKYSTATUS $91
 	.alias kernal_load_or_verify_flag $93
 	.alias current_file_num $98
+	.alias LDTND $98 ; number of entries in LAT / FAT / SAT tables
 	.alias DFLTN $99
 	.alias input_device_number DFLTN
 	; bit 6 = error messages, bit 7 = control messages
@@ -58,6 +59,11 @@
 	;; - 'Compute's Mapping the Commodore 64', page 32
 	.alias CMP0 $B0 ;; $B0-$B1
 
+	;; Kernal tables for opened files, 10 entries each
+	.alias LAT $0259 ; logical file numbers
+	.alias FAT $0263 ; device numbers
+	.alias SAT $026D ; secondary addresses
+	
 	; "Compute's Mapping the 64" book
 	.alias keyboard_buffer $0277
 	.alias MEMSTR $0281

c64/kernal/clall.s

@@ -1,2 +1,16 @@
+
 clall:
-	rts
+
+	;; Implemented according to 'C64 Programmer's Reference Guide', page 281
+	;; Not entirely sure if it just sets LDTND to 0 or actually calls CLOSE,
+	;; but calling CLOSE for all open channels seems to be the safest
+
+	ldy LDTND
+	beq +
+	dey
+	lda LAT, y
+	jsr close
+	jmp clall
+*
+	;; 'C64 Programmers Reference Guide', page 281, claims it calls CLRCHN too
+	jmp clrchn

c64/kernal/close.s

@@ -1,3 +1,41 @@
 ; Function defined on pp272-273 of C64 Programmers Reference Guide
 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
+	
+	;; 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
+*
+	iny
+	cpy #$0A
+	bpl +
+	lda LAT, y
+	sta LAT-1, y
+	lda FAT, y
+	sta FAT-1, y
+	lda SAT, y
+	sta SAT-1, y
+	jmp -
+*
+	;; Decrement the list size variable
+	dec LDTND
+	;; FALLTHROUGH (for now) - success
+	
+close_error_not_found:
+	
+	;; XXX it seems that this function can't report errors, am I right?
 	rts

c64/kernal/open.s

@@ -4,6 +4,38 @@
 
 open:
 
+	;; LAT / FAT / SAT support implemented according to
+	;; 'Compute's Mapping the Commodore 64', page 52
+
+	;; Check if we have space in tables
+
+	ldy LDTND
+	cpy #$0A
+	bcs +
+	bmi open_has_space
+*
+	jsr printf
+	.byte "FULL", $0D, 0
+
+	;; Table is full - according to https://codebase64.org/doku.php?id=base:kernalreference
+	;; C flag set means error occured
+	sec
+	rts
+
+open_has_space:
+
+	;; Update the tables
+
+	lda current_logical_filenum
+	sta LAT, y
+	lda current_device_number
+	sta FAT, y
+	lda current_secondary_address
+	sta SAT, y
+
+	iny
+	sty LDTND
+
 	;; Kernal API is shared between several types of devices - we have
 	;; to dispatch the call to appropriate subroutine
 
@@ -54,17 +86,15 @@ open_iec:
 	jsr iec_assert_atn
 
 	;; CLK is now asserted, and we are ready to transmit a byte
-	lda #$20 ; listen
-	clc
-	adc current_device_number
-	jsr iec_tx_byte
-	bcs open_error
+	lda current_device_number
+	jsr listen
+	bcs open_iec_error
 
 	;; Indicate success
 	lda #$00
 	clc	
 
-open_error:
+open_iec_error:
 	;; Re-enable interrupts and return
 	;; (iec_tx_byte will have set/cleared C flag and put result code
 	;; in A if it was an error).