various LOAD improvements

STATUS.md

@@ -32,6 +32,7 @@ The following ROM features are currently missing:
 * BASIC expression parsing
 * floating point routines
 * tape (normal mode) support
+* tape loading ignores secondary address
 * IEC support for SAVE
 * RS-232 support
 * NMI handling is incomplete

c64/aliases/,aliases_ram_lowmem.s

@@ -94,7 +94,11 @@
 	.label DFLTN     = $99  //          default input device
 	.label DFLTO     = $9A  //          default output device
 	.label PRTY      = $9B  //          tape storage for parity/checksum
+#if !CONFIG_TAPE_NORMAL && !CONFIG_TAPE_TURBO	
 	.label DPSW      = $9C  //          -- NOT IMPLEMENTED --
+#else
+    .label COLSTORE  = $9C  //          [!] screen border storage for tape routines 
+#endif
 	.label MSGFLG    = $9D  //          bit 6 = error messages, bit 7 = control message
 	.label PTR1      = $9E  //          -- NOT IMPLEMENTED --
 	.label PTR2      = $9F  //          -- NOT IMPLEMENTED --
@@ -277,6 +281,6 @@
 
 	//                 $314     $334-$33B  -- UNUSED --          free for user software
 	
-	.label TBUFFR    = $33C  // $33C-$3FB, -- NOT IMPLEMENTED --, tape buffer
+	.label TBUFFR    = $33C  // $33C-$3FB  [!] tape buffer, our usage details differ
 
 	//                 $3FC     $3FC-$3FF  -- UNUSED --          free for user software

c64/kernal/assets/kernal_messages.s

@@ -17,6 +17,7 @@
 
 #if CONFIG_TAPE_NORMAL || CONFIG_TAPE_TURBO
 .label __MSG_KERNAL_PRESS_PLAY         = __msg_kernalplay               - __msg_kernal_first
+.label __MSG_KERNAL_FOUND              = __msg_kernalfound              - __msg_kernal_first
 #endif
 
 #if CONFIG_SHOW_PAL_NTSC
@@ -70,6 +71,11 @@ __msg_kernalplay:
 	.text "PRESS PLAY ON TAPE"
 	.byte $80 + $0D // end of string mark + return
 
+__msg_kernalfound:
+	.byte $0D
+	.text "FOUND"
+	.byte $80 + $20 // end of string mark + space
+
 #endif
 
 #if CONFIG_SHOW_PAL_NTSC

c64/kernal/iec/iec_wait1ms.s

@@ -4,7 +4,7 @@
 //
 // On NTSC this means 1023 cycles (slightly less on PAL, but we have to be sure).
 // We can't count on badlines, as the screen might be disabled.
-// Delay here is implemeented using VIC-II raster register. Since one raster is
+// Delay here is implemented using VIC-II raster register. Since one raster is
 // 63 cycles, we need at least 17 full rasters to be 100% sure we wait enough
 
 
@@ -12,7 +12,15 @@
 
 
 iec_wait1ms:
+
 	ldx #18 // we probably won't start with the beginning of raster
+
+#endif // CONFIG_IEC
+#if CONFIG_IEC || CONFIG_TAPE_TURBO || CONFIG_TAPE_NORMAL
+
+wait_x_bars: // additional entry point for tape support
+             // has to preserve .Y and put .X to 0
+
 	lda VIC_RASTER
 !:
 	cmp VIC_RASTER
@@ -24,4 +32,4 @@ iec_wait1ms:
 	rts
 
 
-#endif // CONFIG_IEC
+#endif // CONFIG_IEC || CONFIG_TAPE_TURBO || CONFIG_TAPE_NORMAL

c64/kernal/iec/load_iec.s

@@ -90,9 +90,9 @@ iec_load_loop:
 	jsr lvs_handle_byte_load_verify
 	bcs load_iec_error
 
-	// Advance pointer to data
+	// Advance pointer to data; it is OK if it advances past $FFFF,
+	// one autostart technique does exactly this
 	jsr lvs_advance_pointer
-	bcs_far lvs_wrap_around_error
 	
 	// Handle STOP key; it is probably an overkill to do it
 	// with every byte, once per 32 bytes should be enough

c64/kernal/iostack/lvs_helpers.s

@@ -79,16 +79,10 @@ lvs_handle_byte_verify:
 lvs_advance_pointer:
 
 	// Advance pointer
-	inc STAL
-	beq !+
-	jmp lvs_success_end
-!:
-	inc STAL+1
-	// If we wrap around to $0000, then this is bad.
+	inc STAL+0
 	bne !+
-	jmp lvs_error_end
+	inc STAL+1
 !:
-	clc
 	rts
 
 
@@ -155,12 +149,6 @@ lvs_display_done:
 	ldx #__MSG_KERNAL_TO_HEX
 	jmp !-
 
-lvs_wrap_around_error:
-
-	// This error is probably not even detected by C64 Kernal;
-	// report BASIC error code that looks the most sane
-	lda #B_ERR_OVERFLOW
-
 lvs_error_end:
 
 	sec

c64/kernal/tape/load_tape_turbo.s

@@ -7,66 +7,75 @@
 // - https://codebase64.pokefinder.org/doku.php?id=base:turbotape_loader_source
 
 
+// XXX use calibration bits to improve reading
+// XXX handle load address from Kernal API
+// XXX add name matching
+
+
 #if CONFIG_TAPE_TURBO
 
 
 load_tape_turbo:
 
-	// XXX prepare SID, store screen color somewhere, read header
-
 	jsr tape_ditch_verify              // only LOAD is supported, no VERIFY
 
-	ldy #$00
-	sty PRTY                           // initial checksum value
-
-	sty CIA2_TIMAHI
+	lda #$00
+	sta CIA2_TIMAHI
 	lda #$FE                           // timer threshold for TurboTape
 	sta CIA2_TIMALO
 
 	jsr tape_ask_play
 
+	// FALLTROUGH
+
+load_tape_turbo_header:
+
 	// Read file header
 
-	ldy #$00
+	jsr tape_turbo_sync
 
-	jsr tape_turbo_sync                // .X gets set to 0
-
-	stx STAL+0                         // instead of a later lda, sta
-	jsr tape_turbo_get_byte            // important trick - save time/bytes by using y-indexing
-	tay
+	ldy #$15
 !:
-	jsr tape_turbo_get_byte	
-	sta STAL+1,x                       // .X still 0
-	inx
-	cpx #$03
-	bne !-
+	jsr tape_turbo_get_byte
+	sta (TAPE1), y
+	dey
+	bpl !-
+
+	jsr tape_handle_header
+	bcs load_tape_turbo_header         // if name does not match, look for other header
+
+	// FALLTROUGH
+
+load_tape_turbo_payload:
 
 	// Read file payload
 
 	jsr tape_turbo_sync                // .X gets set to 0
 
+	ldy #$00
+	sty PRTY                           // initial checksum value
+
 	// FALLTROUGH
 
 load_tape_turbo_loop:
 
 	jsr tape_turbo_get_byte
 
-	dec CPU_R6510                      // to load below i/o area!
-
-	sta (STAL),y	
-	eor PRTY
-	sta PRTY
-
+	dec CPU_R6510                      // to load below I/O area
+	sta (STAL),y
 	inc CPU_R6510
 
-	iny
-	bne !+
-	inc STAL+1
-!:
-	cpy MEMUSS+0
+	eor PRTY                           // handle checksum
+	sta PRTY
+
+	jsr lvs_advance_pointer
+
 	lda STAL+1
-	sbc MEMUSS+1
-	bcc load_tape_turbo_loop
+	cmp EAL+1
+	bne load_tape_turbo_loop
+	lda STAL+0
+	cmp EAL+0
+	bne load_tape_turbo_loop
 
 	// Verify the checksum
 
@@ -75,7 +84,6 @@ load_tape_turbo_loop:
 	beq_far tape_load_success
 	jmp tape_load_error
 
-
 tape_turbo_get_byte:
 
 	lda #$01	

c64/kernal/tape/tape_common.s

@@ -7,6 +7,10 @@
 #if CONFIG_TAPE_NORMAL || CONFIG_TAPE_TURBO
 
 
+//
+// Check if VERIFY asked - if yes, terminate loading
+//
+
 tape_ditch_verify:
 
 	lda VERCKK
@@ -18,24 +22,52 @@ tape_ditch_verify:
 	jmp lvs_device_not_found_error
 
 
+//
+// Handle tape deck motor
+//
+
 tape_motor_off:
 
 	lda CPU_R6510
 	ora #$20
-	sta CPU_R6510 
-
-	rts
-
+	bne !+                             // branch always
 
 tape_motor_on:
 
 	lda CPU_R6510
 	and #($FF - $20)
+!:
 	sta CPU_R6510 
-
 	rts
 
 
+//
+// Handle screen (visible/blanked) + tape deck motor (on/off),
+// store/restore screen color
+//
+
+tape_screen_show_motor_off:
+
+	jsr tape_motor_off
+
+	lda COLSTORE
+	sta VIC_EXTCOL
+
+	jmp screen_show
+
+tape_screen_hide_motor_on:
+	lda VIC_EXTCOL
+	sta COLSTORE
+
+	jsr screen_blank
+	jmp tape_motor_on
+
+
+//
+// Ask user to press PLAY on tape deck, 
+// Unless user cancelled loading, blank screen and start motor
+//
+
 tape_ask_play:
 
 	sei                                // timing is critical for tape loading
@@ -45,9 +77,18 @@ tape_ask_play:
 	ldx #__MSG_KERNAL_PRESS_PLAY
 	jsr print_kernal_message
 
+	// Clean the SID registers, we need it for sound effects
+
+	lda #$00
+	ldy #$1C
+!:
+	sta __SID_BASE, y
+	dey
+	bpl !-
+
 	// FALLTROUGH
 
-tape_wait_button_loop:
+tape_wait_play_loop:
 
 	jsr udtim_keyboard
 	jsr STOP
@@ -61,27 +102,139 @@ tape_wait_button_loop:
 !:
 	lda CPU_R6510
 	and #$10                           // check for pressed button
-	bne tape_wait_button_loop
+	bne tape_wait_play_loop
 
-	jsr screen_blank
-	jsr tape_motor_on
+	jmp tape_screen_hide_motor_on
 
+
+//
+// Handle file header - display it, decide whether load the file or not, etc.
+//
+
+tape_handle_header:
+
+	jsr tape_screen_show_motor_off
+
+	// Header structure described here:
+	// - https://www.luigidifraia.com/c64/docs/tapeloaders.html#turbotape64
+	//
+	// 1 byte   - file type (0 = data, odd value = relocatable, even value = non-relocatable)
+	// 2 bytes  - start address
+	// 2 bytes  - end address + 1
+	// 1 byte   - if $0B (tape timing) contained at the time of saving     XXX handle this
+	// 16 bytes - filename, padded with 0x20
+	//
+	// Out tape buffer contains header in reversed order
+
+	// Print FOUND + file name
+
+	ldx #__MSG_KERNAL_FOUND
+	jsr print_kernal_message
+
+	ldy #$10
+!:
+	lda (TAPE1), y
+	jsr JCHROUT
+	dey
+	bpl !-
+	jsr print_return
+
+	// Header, wait for user decision
+
+	jsr tape_header_get_decision
+	bcs tape_handle_header_skip
+
+	// XXX Perform filename matching
+
+	// Setup STAL and EAL
+
+	ldy #$15
+	lda (TAPE1), y
+	sta STAL+0
+
+	dey
+	lda (TAPE1), y
+	sta STAL+1
+
+	dey
+	lda (TAPE1), y
+	sta EAL+0
+
+	dey
+	lda (TAPE1), y
+	sta EAL+1
+
+	// Print LOADING
+
+	jsr lvs_display_loading_verifying
+
+	// Load the file
+
+	jsr tape_screen_hide_motor_on
+	
+	clc
+	rts
+
+tape_handle_header_skip:
+
+	// Skip this file
+
+	jsr tape_screen_hide_motor_on
+	
+	sec
 	rts
 
 
+//
+// Get user decision whether to load the file or not
+//
+
+tape_header_get_decision:
+
+	ldy #$00
+!:
+	jsr udtim_keyboard
+	lda STKEY
+	bpl tape_header_wait_stop          // STOP pressed
+	and #$10
+	beq tape_header_wait_space         // space pressed
+
+	ldx #$80
+	jsr wait_x_bars                    // sets .X to 0
+	dex
+	jsr wait_x_bars
+
+	dey
+	bne !-
+
+	// FALLTROUGH - timeout
+
+tape_header_wait_space:
+	
+	clc
+	rts
+
+tape_header_wait_stop:
+	
+	sec
+	rts
+
+
+//
+// Report that file loading succeeded (or not)
+//
+
 tape_load_success:
 
-	jsr screen_show
-	jsr tape_motor_off
+	jsr tape_screen_show_motor_off
+	jsr lvs_display_done
 	
 	cli
 	jmp lvs_success_end
 
-
 tape_load_error:
 
-	jsr screen_show
-	jsr tape_motor_off
+	jsr tape_screen_show_motor_off
 
 	cli
 	jmp lvs_load_verify_error