more JiffyDOS code - low nibble TX, general turbo dispatcher

c64/kernal/iec/acptr.s

@@ -14,7 +14,11 @@ ACPTR:
 	jsr kernalstatus_reset
 	
 #if CONFIG_IEC
+#if CONFIG_IEC_JIFFYDOS
+	jmp iec_rx_dispatch
+#else // no turbo supported
 	jmp iec_rx_byte
+#endif
 #else
 	jmp kernalerror_ILLEGAL_DEVICE_NUMBER
 #endif

c64/kernal/iec/ciout.s

@@ -33,7 +33,11 @@ ciout_store_in_buffer:
 ciout_send_byte:
 
 	clc // don't send with EOI
+#if CONFIG_IEC_JIFFYDOS
+	jsr iec_tx_dispatch
+#else // no turbo supported
 	jsr iec_tx_byte
+#endif
 	inc C3PO // iec_tx_byte sets it to 0, but we still have something to send
 	jmp ciout_store_in_buffer
 

c64/kernal/iec/f000.iec_jiffydos.s

@@ -30,6 +30,8 @@ iec_tx_byte_jiffydos:
 	// Prepare nibbles to send
 	lda TBTCNT
 	and #$0F
+	tax
+	lda iec_jiffydos_bittable, X       // low nibble has to be encoded
 	pha
 	lda TBTCNT
 	and #$F0
@@ -57,29 +59,16 @@ __jd_check1:
 	and #%00110000                     // clear everything but CLK/DATA
 	sta CIA2_PRA                       // bits 6 and 7 on CLK/DATA
 
-	// Send low nibble; cycles: XXX
+	// Send low nibble; cycles: 4 + 3 + 4 + 2 + 2 + 2 + 4 = 21
+	pla                                // retrieve low nibble from stack
+	ora C3PO                           // restore VIC-II and RS-232 bits
+	sta CIA2_PRA
+	ror
+	ror
+	and #%00110000                     // clear everything but CLK/DATA
+	sta CIA2_PRA
 
-	// XXX something strange seems to happen with low nibble:
 
-	// $0 -> $00
-	// $1 -> $80 = $10 + $70
-	// $2 -> $20
-	// $3 -> $A0 = $30 + $70
-	// $4 -> $40
-	// $5 -> $C0 = $50 + $70
-	// $6 -> $60
-	// $7 -> $E0 = $70 + $70
-	
-	// $8 -> $10 = $80 - $70
-	// $9 -> $90
-	// $A -> $30 = $A0 - $70
-	// $B -> $B0
-	// $C -> $50 = $C0 - $70
-	// $D -> $D0
-	// $E -> $70 = $E0 - $70
-	// $F -> $F0
-
-	// XXX why??? how this is calculated???
 
 	// XXX EOI signalled by early CLK (20us delay for non-CLK?)
 

c64/kernal/iec/iec_jiffydos_bittable.s

@@ -0,0 +1,33 @@
+
+//
+// Helper table for encoding lower nibble for JiffyyDOS,
+// values found by observing the actual transfer
+//
+
+#if CONFIG_IEC_JIFFYDOS
+
+
+	// XXX consider calculating the values on-the-fly
+
+iec_jiffydos_bittable:
+
+	.byte $00
+	.byte $80    // $10 + $70
+	.byte $20
+	.byte $A0    // $30 + $70
+	.byte $40
+	.byte $C0    // $50 + $70
+	.byte $60
+	.byte $E0    // $70 + $70
+	
+	.byte $10    // $80 - $70
+	.byte $90
+	.byte $30    // $A0 - $70
+	.byte $B0
+	.byte $50    // $C0 - $70
+	.byte $D0
+	.byte $70    // $E0 - $70
+	.byte $F0
+
+
+#endif // CONFIG_IEC_JIFFYDOS

c64/kernal/iec/iec_rx_dispatch.s

@@ -0,0 +1,32 @@
+
+//
+// Arbitration code for normal/turbo transfer
+//
+
+
+#if CONFIG_IEC_JIFFYDOS
+
+
+iec_rx_dispatch:
+
+	lda IECPROTO
+#if CONFIG_IEC_JIFFYDOS
+	cmp #$01
+	beq iec_rx_dispatch_jiffydos
+#endif // CONFIG_IEC_JIFFYDOS
+
+	// FALLTROUGH
+
+iec_rx_dispatch_normal:
+
+	plp
+	jmp iec_rx_byte
+
+#if CONFIG_IEC_JIFFYDOS
+iec_rx_dispatch_jiffydos:
+	plp
+	jmp iec_rx_byte_jiffydos
+#endif // CONFIG_IEC_JIFFYDOS
+
+
+#endif // any turbo supported

c64/kernal/iec/iec_tx_byte.s

@@ -68,21 +68,21 @@ iec_tx_common_sendbit:
     cpx #$00
     bne !+                             // branch if not sending the last bit
 
-    ldy #$1B                           // 400us is nearly 410 cycles on NTSC
+    ldy #$25                           // 400us is nearly 410 cycles on NTSC
-                                       // loop iteration below is 15 cycles,
+                                       // loop iteration below is 11 cycles,
                                        // and several cycles were already used
 iec_jiffydos_detect_loop:
 	lda CIA2_PRA                       // 4 cycles
 	bpl iec_jiffydos_detected          // 2 cycles
 	dey                                // 2 cycles
-	bne iec_jiffydos_detect_loop       // 2 cycles
+	bne iec_jiffydos_detect_loop       // 3 cycles if branch
 
-	lda #$00                           // 2 cycles
+	lda #$00                           // normal protocol
-	beq iec_jiffydos_store_proto       // 3 cycles, branch always
+	skip_2_bytes_trash_nvz
 
 iec_jiffydos_detected:
 
-	panic #$FF // WHOAAAA! He wants to speak jiffy, but I do not know this language yet!
+	lda #$01                           // JiffyDOS protocol
 
 iec_jiffydos_store_proto:
 	sta IECPROTO

c64/kernal/iec/iec_tx_dispatch.s

@@ -0,0 +1,33 @@
+
+//
+// Arbitration code for normal/turbo transfer
+//
+
+
+#if CONFIG_IEC_JIFFYDOS
+
+
+iec_tx_dispatch:
+
+	php                                // preserve C flag for EOI indication
+	lda IECPROTO
+#if CONFIG_IEC_JIFFYDOS
+	cmp #$01
+	beq iec_tx_dispatch_jiffydos
+#endif // CONFIG_IEC_JIFFYDOS
+
+	// FALLTROUGH
+
+iec_tx_dispatch_normal:
+
+	plp
+	jmp iec_tx_byte
+
+#if CONFIG_IEC_JIFFYDOS
+iec_tx_dispatch_jiffydos:
+	plp
+	jmp iec_tx_byte_jiffydos
+#endif // CONFIG_IEC_JIFFYDOS
+
+
+#endif // any turbo supported

c64/kernal/iec/load_iec.s

@@ -71,10 +71,18 @@ load_iec:
 
 	// Get load address
 
+#if CONFIG_IEC_JIFFYDOS
+	jsr iec_rx_dispatch
+#else // no turbo supported
 	jsr iec_rx_byte
+#endif
 	bcs load_iec_file_not_found
 	sta EAL+0
+#if CONFIG_IEC_JIFFYDOS
+	jsr iec_rx_dispatch
+#else // no turbo supported
 	jsr iec_rx_byte
+#endif
 	bcs load_iec_file_not_found
 	sta EAL+1
 
@@ -92,7 +100,11 @@ load_iec:
 
 iec_load_loop:
 	// We are now ready to receive bytes
+#if CONFIG_IEC_JIFFYDOS
+	jsr iec_rx_dispatch
+#else // no turbo supported
 	jsr iec_rx_byte
+#endif
 	bcs load_iec_error
 
 	// Handle the byte (store in memory / verify)

c64/kernal/iec/save_iec.s

@@ -48,12 +48,20 @@ save_iec:
 	lda STAL+0
 	sta TBTCNT
 	clc
+#if CONFIG_IEC_JIFFYDOS
+	jsr iec_tx_dispatch
+#else // no turbo supported
 	jsr iec_tx_byte
+#endif
 
 	lda STAL+1
 	sta TBTCNT
 	clc
+#if CONFIG_IEC_JIFFYDOS
+	jsr iec_tx_dispatch
+#else // no turbo supported
 	jsr iec_tx_byte
+#endif
 
 	jsr lvs_setup_MEMUSS
 	ldy #$00
@@ -70,7 +78,11 @@ iec_save_loop:
 	// Send the byte
 	sta TBTCNT
 	clc
+#if CONFIG_IEC_JIFFYDOS
+	jsr iec_tx_dispatch
+#else // no turbo supported
 	jsr iec_tx_byte
+#endif
 
 	// Next iteration
 	jsr lvs_advance_MEMUSS_check_EAL

c64/kernal/iec/talk.s

@@ -26,6 +26,16 @@ TALK:
 	// Encode and execute the command
 	ora #$40
 
+#if CONFIG_IEC_JIFFYDOS
+
+	// XXX temporary, until receiving is implemented too
+	sta TBTCNT
+	lda #$00 // standard protocol
+	sta IECPROTO
+	jmp iec_tx_command
+
+#endif // CONFIG_IEC_JIFFYDOS
+
 common_talk_listen: // common part of TALK and LISTEN
 
 	sta TBTCNT