more work towards JiffyDOS

c64/kernal/iec/f000.iec_jiffydos.s

@@ -10,30 +10,28 @@
 #if CONFIG_IEC_JIFFYDOS
 
 
+// JiffyDOS timing regime is very strict - before transmitting anything
+// we need to disable sprites and (if screen is not disabled) wait for
+// appropriate moment, so that no badline interruption can happen
+
+
 iec_tx_byte_jiffydos:
 
-	// XXX disable screen - temporary, just for testing
-	tay
-	lda VIC_SCROLY
-	and #($FF - $10)
-	sta VIC_SCROLY
-	lda VIC_RASTER
-!:
-	cmp VIC_RASTER
-	beq !-
-	tya
-
-	// JiffyDOS timing regime is very strict - before transmitting anything
-	// we need to disable sprites and (if screen is not disabled) wait for
-	// appropriate moment, so that no badline interruption can happen
-	
 	jsr jiffydos_hide_sprites
 	pha                                // store previous sprite status on stack
+
+	// XXX prepare bit pairs too send
+
+	// XXX lda TBTCNT
+	// XXX bits to stack: 0, 2
+	// XXX bits to stack: 1, 3
+	// XXX bits to stack: 7, 6
+	// XXX bits to stack: 5, 4
+
 	jsr jiffydos_wait_line
 
 __jd_check1:
 
-
 	// XXX send byte
 
 
@@ -51,23 +49,24 @@ __jd_check1:
 
 iec_rx_byte_jiffydos:
 	
-	// XXX disable screen - temporary, just for testing
-	lda VIC_SCROLY
-	and #($FF - $10)
-	sta VIC_SCROLY
-	lda VIC_RASTER
-!:
-	cmp VIC_RASTER
-	beq !-
-
-	// JiffyDOS timing regime is very strict - before transmitting anything
-	// we need to disable sprites and (if screen is not disabled) wait for
-	// appropriate moment, so that no badline interruption can happen
-	
 	jsr jiffydos_hide_sprites
 	pha                                // store previous sprite status on stack
+	
+	// Wait until device is ready to send
+	jsr iec_wait_for_clk_release
+
+	// Prepare 'start sending' message
+	lda CIA2_PRA
+	and #$FF - BIT_CIA2_PRA_DAT_OUT    // release
+	pha
+
+	// Wait for appropriate moment
 	jsr jiffydos_wait_line
 
+	// Ask device to start sending bits
+	pla
+	sta CIA2_PRA
+
 
 	// XXX retrieve byte
 
@@ -95,7 +94,8 @@ jiffydos_wait_line:
 	// To give the transfer routine as much time as possible,
 	// wait till a badline
 
-	// XXX this has to be carefully tested!
+	// XXX this is probably overkill, most likely it is enough to avoid 2 (3?) lines
+	//     before badline - to be adjusted in the future
 !:
 	sec
 	lda VIC_SCROLY
@@ -104,7 +104,7 @@ jiffydos_wait_line:
 	bne !-
 
 jiffydos_wait_line_done:
-	rts                                // XXX 6 cycles... we might be forced to inline this routine
+	rts
 
 
 __jd_check2:

c64/kernal/iec/iec_tx_byte.s

@@ -75,7 +75,7 @@ iec_jiffydos_detect_loop:
 	lda CIA2_PRA                       // 4 cycles
 	bpl iec_jiffydos_detected          // 2 cycles
 	dey                                // 2 cycles
-	bne iec_jiffydos_detect_loop       // 2 cyycles
+	bne iec_jiffydos_detect_loop       // 2 cycles
 
 	lda #$00                           // 2 cycles
 	beq iec_jiffydos_store_proto       // 3 cycles, branch always

c64/kernal/iec/iec_tx_command.s

@@ -16,15 +16,6 @@ iec_tx_command:
 	phx_trash_a
 	phy_trash_a
 
-#if CONFIG_IEC_JIFFYDOS
-
-	// With each and every command, check whether device wants to talk JiffyDOS protocol
-
-	lda #$FF // unknown protocol
-	sta IECPROTO
-
-#endif // CONFIG_IEC_JIFFYDOS
-
 	// Notify all devices that we are going to send a byte
 	// and it is going to be a command (pulled ATN)
 	jsr iec_pull_atn_clk_release_data

c64/kernal/iec/talk.s

@@ -29,6 +29,19 @@ TALK:
 common_talk_listen: // common part of TALK and LISTEN
 
 	sta TBTCNT
+
+#if CONFIG_IEC_JIFFYDOS
+
+	// It seems that only TALK/LISTEN is used to detect the JiffyDOS support
+
+	lda #$FF // unknown protocol - check what is supported
+	sta IECPROTO
+
+	// FALLTROUGH
+
+#endif // CONFIG_IEC_JIFFYDOS
+
+
 	jmp iec_tx_command
 
 #else

c64/kernal/iec/unlsn.s

@@ -18,6 +18,13 @@ UNLSN:
 	// According to serial-bus.pdf (page 15) this routine flushes the IEC out buffer
 	jsr iec_tx_flush
 
+#if CONFIG_IEC_JIFFYDOS
+
+	lda #$00 // switch back to standard protocol
+	sta IECPROTO
+
+#endif
+
 	// Buffer empty, send the command
 	lda #$3F
 

c64/kernal/iec/untlk.s

@@ -18,6 +18,13 @@ UNTLK:
 	// According to serial-bus.pdf (page 15) this routine flushes the IEC out buffer
 	jsr iec_tx_flush
 
+#if CONFIG_IEC_JIFFYDOS
+
+	lda #$00 // switch back to standard protocol
+	sta IECPROTO
+
+#endif
+
 	// Buffer empty, send the command
 	lda #$5F