improved tape system autodetection

c64/,,config_custom.s

@@ -56,7 +56,7 @@
 
 #define CONFIG_TAPE_NORMAL
 #define CONFIG_TAPE_TURBO
-#define CONFIG_TAPE_AUTODETECT         // not fully done yet!
+#define CONFIG_TAPE_AUTODETECT         // mostly works, but not fullyy done yet!
 // #define CONFIG_TAPE_NO_KEY_SENSE
 // #define CONFIG_TAPE_NO_MOTOR_CONTROL
 

c64/aliases/,aliases_config.s

@@ -168,8 +168,8 @@
 
 // Check that tape configuration is correct
 {
-#if !CONFIG_TAPE_TURBO && CONFIG_TAPE_TURBO_AUTOCALIBRATE
-	.error "CONFIG_TAPE_TURBO_AUTOCALIBRATE requires CONFIG_TAPE_TURBO*"
+#if (!CONFIG_TAPE_NORMAL || !CONFIG_TAPE_TURBO) && CONFIG_TAPE_AUTODETECT
+	.error "CONFIG_TAPE_AUTODETECT requires both CONFIG_TAPE_NORMAL and CONFIG_TAPE_TURBO"
 #endif
 }
 

c64/kernal/tape/load_tape_normal.s

@@ -44,7 +44,7 @@ load_tape_normal:
 
 	jsr tape_ditch_verify              // only LOAD is supported, no VERIFY
 
-#if CONFIG_TAPE_TURBO && CONFIG_TAPE_AUTODETECT
+#if CONFIG_TAPE_AUTODETECT
 
 	// Prepare for sound effects in case of turbo takeover
 	jsr tape_clean_sid
@@ -55,7 +55,7 @@ load_tape_normal:
 	jsr tape_common_prepare_cia
 	jsr tape_ask_play
 
-#if CONFIG_TAPE_TURBO && CONFIG_TAPE_AUTODETECT
+#if CONFIG_TAPE_AUTODETECT
 
 	// FALLTROUGH
 

c64/kernal/tape/load_tape_turbo.s

@@ -27,7 +27,7 @@ load_tape_turbo:
 
 	// FALLTROUGH
 
-#if CONFIG_TAPE_NORMAL && CONFIG_TAPE_AUTODETECT
+#if CONFIG_TAPE_AUTODETECT
 
 load_tape_turbo_takeover:             // entry point for turbo->normal takeover
 
@@ -51,6 +51,9 @@ load_tape_turbo_header:
 	// 16 bytes         - filename, padded with 0x20
 
 	jsr tape_turbo_sync_header
+#if CONFIG_TAPE_AUTODETECT
+	bcs_16 load_tape_normal_takeover   // failure, probably not a turbo tape file
+#endif
 	ldy #$00
 	sta (TAPE1), y                     // store header type
 	iny
@@ -106,8 +109,11 @@ load_tape_turbo_payload:
 	sta PRTY
 
 	// Read file payload
-
+!:
 	jsr tape_turbo_sync_payload
+#if CONFIG_TAPE_AUTODETECT
+	bcs !-
+#endif
 
 	// FALLTROUGH
 

c64/kernal/tape/tape_common_autodetect.s

@@ -5,13 +5,13 @@
 //
 // Tries to detect
 //
-// Carry clear - NORMAL, Carry set - TURBO
+// Carry clear - normal, Carry set - turbo
 //
 
-// XXX implement fallback to autodetection, correct screen color for NORMAL
+// XXX implement fallback to autodetection in normal
 
 
-#if CONFIG_TAPE_NORMAL && CONFIG_TAPE_TURBO && CONFIG_TAPE_AUTODETECT
+#if CONFIG_TAPE_AUTODETECT
 
 
 tape_common_autodetect:
@@ -26,18 +26,18 @@ tape_common_autodetect:
 
 tape_common_autodetect_retry:
 
-	// It is not trivial to distinguish between NORMAL and TURBO,
-	// as short pulses of NORMAL (and sync uses only shorts)
-    // have similar lengths as long pulses of TURBO
+	// It is not trivial to distinguish between normal and turbo,
+	// as short pulses of normal (and sync uses only shorts)
+    // have similar lengths as long pulses of turbo
 
 	// Thus, the routine here reads certain amount of pulses
-	// looking for evidence for either NORMAL or TURBO system;
-	// in case of no evidence found, assume NORMAL
+	// looking for evidence for either normal or turbo system;
+	// in case of no evidence found, assume normal
 
-	lda #$00                           // plus = probably NORMAL, minus = TURBO
+	lda #$00                           // plus = probably normal, minus = turbo
 	sta XSAV
 
-	ldy #$60                           // $60 pulses cover 12 bytes of TURBO recording
+	ldy #$60                           // $60 pulses cover 12 bytes of turbo recording
 	jsr tape_normal_get_pulse          // first pulse might be a garbage, ignore it
 
 	// FALLTROUGH
@@ -52,24 +52,24 @@ tape_common_autodetect_loop:
 	cmp #$E8
 	bcs tape_common_autodetect_retry   // this is a VERY short pulse
 
-	// First try to distinguish TURBO short signal (reference: $CD)
-	// from NORMAL signals (reference: $A5 or lower), these values
+	// First try to distinguish turbo short signal (reference: $CD)
+	// from normal signals (reference: $A5 or lower), these values
 	// give us threshold of ($CD + $A5) / 2 = $B9
 
 	cmp #$B9
 	bcc !+
-	dec XSAV                           // above $B9 (so signal is shorter), looks like TURBO 
+	dec XSAV                           // above $B9 (so signal is shorter), looks like turbo 
 !:
-	// Now try to distinguish TURBO signals (reference: $B1 or higher)
-	// from NORMAL medium/long signals (reference: $7D or below), these values
+	// Now try to distinguish turbo signals (reference: $B1 or higher)
+	// from normal medium/long signals (reference: $7D or below), these values
 	// give us threshold of ($B1 + $7D) / 2 = $97
 
 	cmp #$97
 	bcs !+
 	inc XSAV
 !:
-	// The sync for TURBO is not too long - if we have enough evidence,
-	// assume TURBO recording already
+	// The sync for turbo is not too long - if we have enough evidence,
+	// assume turbo recording already
 
 	lda XSAV
 	cmp #$FD
@@ -79,7 +79,7 @@ tape_common_autodetect_loop:
 	dey
 	bpl tape_common_autodetect_loop
 
-	// Last chance for TURBO
+	// Last chance for turbo
 
 	lda XSAV
 	bmi tape_common_autodetect_turbo

c64/kernal/tape/tape_normal_get_data.s

@@ -24,10 +24,10 @@ tape_normal_get_data:
 	lda #$00
 	sta RIPRTY
 
-	// Read the pilot and sync of the block
+	// Read sync of the block
 	ldy #$89
 	jsr tape_normal_sync
-	bcs tape_normal_get_block_done     // XXX make it more error resistant
+	bcs tape_normal_get_block_done
 	jsr tape_normal_get_marker
 
 tape_normal_get_data_loop:
@@ -39,7 +39,7 @@ tape_normal_get_data_loop:
 
 	// Store byte, calculate checksum
 	lda INBIT
-	ldy #$00                           // XXX probably can be optimized out for 65C02
+	ldy #$00
 	sta (MEMUSS), y
 	eor RIPRTY
 	sta RIPRTY
@@ -60,7 +60,7 @@ tape_normal_get_data_loop:
 	sec
 	rts
 
-tape_normal_get_checksum: // XXX handle second copy, with pilot starting from $09
+tape_normal_get_checksum:        // XXX handle second copy, with pilot starting from $09
 
 	lda INBIT
 	eor RIPRTY

c64/kernal/tape/tape_normal_pilot.s

@@ -31,6 +31,9 @@ tape_normal_pilot_common:
 
 tape_normal_pilot_common_restart:
 
+	lda #$0B
+	sta VIC_EXTCOL
+
 	lda FSBLK
 	sta ROPRTY
 

c64/kernal/tape/tape_normal_sync.s

@@ -14,9 +14,14 @@
 
 tape_normal_sync:
 
+	lda #$06
+	sta VIC_EXTCOL
+
 	// Injest bytes of decreasing values
 
-	jsr tape_normal_get_marker         // XXX handle result
+	jsr tape_normal_get_marker
+	bcs tape_normal_sync_fail          // branch if end of data marker
+	
 	jsr tape_normal_get_byte
 	bcs tape_normal_sync_fail
 

c64/kernal/tape/tape_turbo_get_bit.s

@@ -31,5 +31,29 @@ tape_turbo_get_bit:
 
 #endif
 
+	cmp SYNO                           // threshold
+	bcs !+
+
+	clc
+	ror
+	sta IRQTMP+0                       // store half of the last measurement result for short pulse
+
+	lda #$01
+	sta SID_SIGVOL
+	lda #$06
+	sta VIC_EXTCOL
+	sec
+	rts
+!:
+	clc
+	ror
+	sta IRQTMP+1                       // store half of the last measurement result for long pulse
+
+	lda #$00
+	sta SID_SIGVOL
+	sta VIC_EXTCOL
+	clc
+	rts
+
 
 #endif // CONFIG_TAPE_TURBO

c64/kernal/tape/tape_turbo_sync.s

@@ -21,6 +21,9 @@ tape_turbo_sync_header:
 
 	// Synchronize with start of sync sequence
 	jsr tape_turbo_sync_first
+#if CONFIG_TAPE_AUTODETECT
+	bcs tape_turbo_sync_done
+#endif
 
 	// Perform synchronization, double loop, total $C0 * $04 iterations
 	ldx #$C0
@@ -43,6 +46,9 @@ tape_turbo_sync_header:
 tape_turbo_sync_payload:
 
 	jsr tape_turbo_sync_first
+#if CONFIG_TAPE_AUTODETECT
+	bcs tape_turbo_sync_done           // this shopuld not happen
+#endif
 !:
 	ldx #$09                           // 9, 8, ...
 !:
@@ -57,6 +63,14 @@ tape_turbo_sync_payload:
 	dex
 	bne !-
 
+#if CONFIG_TAPE_AUTODETECT
+	clc
+#endif
+
+	// FALLTROUGH
+
+tape_turbo_sync_done:
+
 	rts
 
 

c64/kernal/tape/tape_turbo_sync_first.s

@@ -11,13 +11,43 @@
 
 tape_turbo_sync_first:
 
+#if CONFIG_TAPE_AUTODETECT
+
+	ldy #$00
+!:
 	jsr tape_turbo_get_bit 
 	rol INBIT
 	lda INBIT
+
+	cmp #$FF
+	bne !+
+	iny
+	bpl !-
+	bmi tape_turbo_sync_first_fail     // suspiciously many $FF bytes, probably not a turbo tape
+!:
+	cmp #$02
+	bne tape_turbo_sync_first
+
+	clc
+	rts
+
+tape_turbo_sync_first_fail:
+
+	sec
+	rts
+
+#else // no CONFIG_TAPE_AUTODETECT
+
+	jsr tape_turbo_get_bit 
+	rol INBIT
+	lda INBIT
+
 	cmp #$02
 	bne tape_turbo_sync_first
 
 	rts
 
+#endif
+
 
 #endif