initial work towards burst IEC protocol support

CONFIG.md

@@ -109,10 +109,6 @@ Adds support for the IEEC bus - for serial printers, disk drives, etc.
 
 Needs over 1000 bytes in KERNAL segment. If unsure - enable.
 
-### `CONFIG_IEC_BLANK_SCREEN`
-
-Causes screen blanking during some IEC operations (currently only JiffyDOS file loading) to increase the data transfer performance.
-
 ### `CONFIG_IEC_DOLPHINDOS`
 
 Adds support for DolphinDOS fast protocol to the IEC bus, using UserPort cable.
@@ -131,6 +127,10 @@ Adds support for JiffyDOS fast protocol to the IEC bus.
 
 Needs about 430 bytes in KERNAL segment. If unsure - enable.
 
+### `CONFIG_IEC_JIFFYDOS_BLANK`
+
+Causes screen blanking during iffyDOS file loading to increase performance.
+
 ### `CONFIG_TAPE_NORMAL`
 
 Adds a minimal normal (standard Commodore format) tape support - just LOAD command.

c64/,,config_custom.s

@@ -45,16 +45,19 @@
 // I/O devices
 
 #define CONFIG_IEC
-#define CONFIG_IEC_BLANK_SCREEN
+#define CONFIG_IEC_DOLPHINDOS
-#define CONFIG_IEC_DOLPHINDOS      // not finished yet, but LOAD works
 #define CONFIG_IEC_DOLPHINDOS_FAST
 #define CONFIG_IEC_JIFFYDOS
+#define CONFIG_IEC_JIFFYDOS_BLANK
+// #define CONFIG_IEC_BURST_CIA1       // please keep disabled for now
+// #define CONFIG_IEC_BURST_CIA2       // please keep disabled for now
+// #define CONFIG_IEC_BURST_SOFT       // please keep disabled for now
 
 #define CONFIG_TAPE_NORMAL
 #define CONFIG_TAPE_TURBO
 
-// #define CONFIG_RS232_UP2400    // please keep disabled for now
+// #define CONFIG_RS232_UP2400         // please keep disabled for now
-// #define CONFIG_RS232_UP9600    // please keep disabled for now
+// #define CONFIG_RS232_UP9600         // please keep disabled for now
 
 
 // Multiple SID support

c64/,,config_generic.s

@@ -42,10 +42,10 @@
 // I/O devices
 
 #define CONFIG_IEC
-#define CONFIG_IEC_BLANK_SCREEN
 #define CONFIG_IEC_DOLPHINDOS
 #define CONFIG_IEC_DOLPHINDOS_FAST
 #define CONFIG_IEC_JIFFYDOS
+#define CONFIG_IEC_JIFFYDOS_BLANK
 
 #define CONFIG_TAPE_NORMAL
 #define CONFIG_TAPE_TURBO

c64/,,config_mega65.s

@@ -42,10 +42,10 @@
 // I/O devices
 
 #define CONFIG_IEC
-#define CONFIG_IEC_BLANK_SCREEN
 // #define CONFIG_IEC_DOLPHINDOS
 // #define CONFIG_IEC_DOLPHINDOS_FAST
 #define CONFIG_IEC_JIFFYDOS
+#define CONFIG_IEC_JIFFYDOS_BLANK
 
 // #define CONFIG_TAPE_NORMAL
 // #define CONFIG_TAPE_TURBO

c64/,,config_testing.s

@@ -42,10 +42,10 @@
 // I/O devices
 
 #define CONFIG_IEC
-// #define CONFIG_IEC_BLANK_SCREEN
 #define CONFIG_IEC_DOLPHINDOS
 // #define CONFIG_IEC_DOLPHINDOS_FAST
 #define CONFIG_IEC_JIFFYDOS
+// #define CONFIG_IEC_JIFFYDOS_BLANK
 
 // #define CONFIG_TAPE_NORMAL
 #define CONFIG_TAPE_TURBO

c64/,,config_ultimate64.s

@@ -42,10 +42,10 @@
 // I/O devices
 
 #define CONFIG_IEC
-#define CONFIG_IEC_BLANK_SCREEN
 #define CONFIG_IEC_DOLPHINDOS
 #define CONFIG_IEC_DOLPHINDOS_FAST
 #define CONFIG_IEC_JIFFYDOS
+#define CONFIG_IEC_JIFFYDOS_BLANK
 
 #define CONFIG_TAPE_NORMAL
 #define CONFIG_TAPE_TURBO

c64/aliases/,aliases_config.s

@@ -112,10 +112,15 @@
 }
 
 
-// Check that I/O configuration is correct
+
+// Check that IEC configuration is correct
 {
-#if CONFIG_RS232_UP9600 && (CONFIG_TAPE_NORMAL || CONFIG_TAPE_TURBO)
+#if CONFIG_IEC_JIFFYDOS && !CONFIG_IEC
-	.error "CONFIG_RS232_UP9600 is not compatible with CONFIG_TAPE_*"
+	.error "CONFIG_IEC_JIFFYDOS requires CONFIG_IEC"
+#endif
+
+#if CONFIG_IEC_JIFFYDOS_BLANK && !CONFIG_IEC_JIFFYDOS
+	.error "CONFIG_IEC_JIFFYDOS_BLANK requires CONFIG_IEC_JIFFYDOS"
 #endif
 
 #if CONFIG_IEC_DOLPHINDOS && !CONFIG_IEC
@@ -126,8 +131,35 @@
 	.error "CONFIG_IEC_DOLPHINDOS_FAST requires CONFIG_IEC_DOLPHINDOS"
 #endif
 
-#if CONFIG_IEC_JIFFYDOS && !CONFIG_IEC
+#if (CONFIG_IEC_BURST_CIA1 || CONFIG_IEC_BURST_CIA1 || CONFIG_IEC_BURST_SOFT) && !CONFIG_IEC
-	.error "CONFIG_IEC_JIFFYDOS requires CONFIG_IEC"
+	.error "CONFIG_IEC_BURST_* requires CONFIG_IEC"
+#endif
+
+#if CONFIG_IEC_BURST_SOFT && !CONFIG_MB_MEGA_65
+	.error "CONFIG_IEC_BURST_SOFT requires CONFIG_MB_MEGA_65"
+#endif
+
+	.var selected_iec_burst = 0;
+
+#if CONFIG_IEC_BURST_CIA1
+	.eval selected_iec_burst++
+#endif
+#if CONFIG_IEC_BURST_CIA2
+	.eval selected_iec_burst++
+#endif
+#if CONFIG_IEC_BURST_SOFT
+	.eval selected_iec_burst++
+#endif
+
+	.if (selected_iec_burst > 1) .error "Please select at most one CONFIG_IEC_BURST_* option" 
+}
+
+
+
+// Check that RS-232 configuration is correct
+{
+#if CONFIG_RS232_UP9600 && (CONFIG_TAPE_NORMAL || CONFIG_TAPE_TURBO)
+	.error "CONFIG_RS232_UP9600 is not compatible with CONFIG_TAPE_*"
 #endif
 
 	.var selected_rs232 = 0;
@@ -143,6 +175,7 @@
 }
 
 
+
 // Check that startup banner configuration is correct
 {
 	.var selected = 0;
@@ -322,13 +355,22 @@
 
 #if CONFIG_IEC
 	.var iec_features_str = "IEC"
+#if CONFIG_IEC_BURST_CIA1
+	.eval iec_features_str = iec_features_str + " BURST1"
+#endif
+#if CONFIG_IEC_BURST_CIA2
+	.eval iec_features_str = iec_features_str + " BURST2"
+#endif
+#if CONFIG_IEC_BURST_SOFT
+	.eval iec_features_str = iec_features_str + " BURST"
+#endif
 #if CONFIG_IEC_DOLPHINDOS
 	.eval iec_features_str = iec_features_str + " DOLPHIN"
 #endif
 #if CONFIG_IEC_JIFFYDOS
 	.eval iec_features_str = iec_features_str + " JIFFY"
 #endif
-#if !CONFIG_IEC_DOLPHINDOS && !CONFIG_IEC_JIFFYDOS
+#if !CONFIG_IEC_BURST_CIA1 && !CONFIG_IEC_BURST_CIA2 && !CONFIG_IEC_BURST_SOFT && !CONFIG_IEC_DOLPHINDOS && !CONFIG_IEC_JIFFYDOS
 	.eval iec_features_str = iec_features_str + " NORMAL"
 #endif
 	.eval features_str = ADD_FEATURE(features_str, iec_features_str)

c64/aliases/,aliases_ram_lowmem.s

@@ -103,7 +103,7 @@
 	.label PTR1      = $9E  //          -- NOT IMPLEMENTED --
 	.label PTR2      = $9F  //          -- NOT IMPLEMENTED --
 	.label TIME      = $A0  // $A0-$A2  jiffy clock
-#if !CONFIG_IEC_JIFFYDOS && !CONFIG_IEC_DOLPHINDOS
+#if !CONFIG_IEC_JIFFYDOS && !CONFIG_IEC_DOLPHINDOS && !CONFIG_IEC_BURST_CIA1 && !CONFIG_IEC_BURST_CIA2 && !CONFIG_IEC_BURST_SOFT
 	.label TSFCNT    = $A3  //          temporary variable for tape and IEC, [!] our usage differs
 #else
 	.label IECPROTO  = $A3  //          -- WIP -- [!] 0 = normal, 1 = JiffyDOS, >= $80 for unknown

c64/kernal/assets/irq_timing_hi.s

@@ -0,0 +1,23 @@
+
+//
+// Values for IRQ generation timer - original idea was:
+//
+// (This value was calculated by running a custom IRQ handler on a C64
+// with original KERNAL, and writing the values of $DC04/5 to the screen
+// in the IRQ handler to see roughly what value the timers must be set to)
+// ldy #<16380
+// ldx #>16380
+
+// Current values selected on the following assumptions:
+//
+// PAL C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
+// is clocked at 0.985248 MHz, so that 1/60s is 16421 ($4025) CPU cycles
+//
+// NTSC C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
+// is clocked at 1.022727 MHz, so that 1/60s is 17045 ($4295) CPU cycles
+
+
+irq_timing_hi:                         // high bytes
+
+	.byte >17045                       // NTSC
+	.byte >16421                       // PAL

c64/kernal/assets/irq_timing_lo.s

@@ -0,0 +1,23 @@
+
+//
+// Values for IRQ generation timer - original idea was:
+//
+// (This value was calculated by running a custom IRQ handler on a C64
+// with original KERNAL, and writing the values of $DC04/5 to the screen
+// in the IRQ handler to see roughly what value the timers must be set to)
+// ldy #<16380
+// ldx #>16380
+
+// Current values selected on the following assumptions:
+//
+// PAL C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
+// is clocked at 0.985248 MHz, so that 1/60s is 16421 ($4025) CPU cycles
+//
+// NTSC C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
+// is clocked at 1.022727 MHz, so that 1/60s is 17045 ($4295) CPU cycles
+
+
+irq_timing_lo:                         // low bytes
+
+	.byte <17045                       // NTSC
+	.byte <16421                       // PAL

c64/kernal/iec/iec_cmd_open.s

@@ -17,13 +17,19 @@ iec_cmd_open: // similar to TKSA, but without turnaround
 !:
 	ora #$F0
 
-#if CONFIG_IEC_DOLPHINDOS
+#if CONFIG_IEC_DOLPHINDOS || CONFIG_IEC_BURST_CIA1 || CONFIG_IEC_BURST_CIA2 || CONFIG_IEC_BURST_SOFT
 
 	sta TBTCNT
 	jsr iec_tx_command
 	bcs !+ // branch if error
 
+#if CONFIG_IEC_DOLPHINDOS
 	jsr dolphindos_detect
+#endif
+#if CONFIG_IEC_BURST_CIA1 || CONFIG_IEC_BURST_CIA2 || CONFIG_IEC_BURST_SOFT
+	jsr burst_detect
+#endif
+
 	jmp iec_tx_command_finalize
 
 #else

c64/kernal/iec/iec_update_eal_by_y.s

@@ -1,6 +1,6 @@
 
 //
-// Common routines for multiple IEC fact protocols
+// Common EAL update routine
 //
 
 

c64/kernal/iec/load_iec.s

@@ -63,9 +63,10 @@ load_iec:
 	bcs load_iec_error
 
 #if CONFIG_IEC_DOLPHINDOS
-
 	jsr dolphindos_detect
-
+#endif
+#if CONFIG_IEC_BURST_CIA1 || CONFIG_IEC_BURST_CIA2 || CONFIG_IEC_BURST_SOFT
+	jsr burst_detect
 #endif
 
 	// We are currently talker, so do the IEC turn around so that we

c64/kernal/iec/save_iec.s

@@ -45,9 +45,10 @@ save_iec:
 	bcs save_iec_dev_not_found
 
 #if CONFIG_IEC_DOLPHINDOS
-
 	jsr dolphindos_detect
-
+#endif
+#if CONFIG_IEC_BURST_CIA1 || CONFIG_IEC_BURST_CIA2 || CONFIG_IEC_BURST_SOFT
+	jsr burst_detect
 #endif
 
 	// Save start address

c64/kernal/iec_fast/burst_cia1_detect.s

@@ -0,0 +1,31 @@
+
+//
+// Helper routine for burst IEC protocol support
+//
+
+//
+// Based on idea by Pasi 'Albert' Ojala
+//
+
+
+#if CONFIG_IEC_BURST_CIA1
+
+
+burst_detect:
+
+#if CONFIG_IEC_JIFFYDOS || CONFIG_IEC_DOLPHINDOS
+
+	lda IECPROTO
+	bmi !+
+	bne burst_detect_fail              // skip if other protocol already detected
+!:
+#endif
+
+	panic #$FF // XXX implement this
+
+burst_detect_fail:
+
+	rts
+
+
+#endif

c64/kernal/iec_fast/burst_cia2_detect.s

@@ -0,0 +1,66 @@
+
+//
+// Helper routine for burst IEC protocol support
+//
+
+//
+// Based on idea by Pasi 'Albert' Ojala
+//
+
+
+#if CONFIG_IEC_BURST_CIA2
+
+
+burst_detect:
+
+#if CONFIG_IEC_JIFFYDOS || CONFIG_IEC_DOLPHINDOS
+
+	lda IECPROTO
+	bmi !+
+	bne burst_detect_fail              // skip if other protocol already detected
+!:
+#endif
+
+	// For extra safety, do it on disabled interupts
+	php
+	sei
+
+	// Set the clock rate to the fastest possible
+	ldy #$01
+	sty CIA2_TIMALO
+	dey
+	sty CIA2_TIMAHI
+
+	// Prepare registers for transfer
+	lda #$C1
+	sta CIA2_CRA                       // start timer A, serial out, TOD 50Hz
+	bit CIA2_ICR                       // clear interrupt register
+
+	// Send test byte
+	lda #$FF                           // $FF keeps DATA released, see https://www.c64-wiki.com/wiki/Fast_serial_bus_protocol
+	sta CIA2_SDR
+
+	// Wait until byte sent
+	lda #$08		                   // interrupt mask
+!:
+	bit CIA2_ICR                       
+	beq !-
+
+	// Now see if we get any byte back
+
+	lda CIA2_SDR    // XXX we do not need a value, we need to know if it was received
+
+
+	panic #$00      // XXX finish this routine
+	
+
+	plp
+
+	// FALLTROUGH
+
+burst_detect_fail:
+
+	rts
+
+
+#endif

c64/kernal/iec_fast/burst_soft_detect.s

@@ -0,0 +1,27 @@
+
+//
+// Helper routine for burst IEC protocol support
+//
+
+
+#if CONFIG_IEC_BURST_SOFT
+
+
+burst_detect:
+
+#if CONFIG_IEC_JIFFYDOS || CONFIG_IEC_DOLPHINDOS
+
+	lda IECPROTO
+	bmi !+
+	bne burst_detect_fail              // skip if other protocol already detected
+!:
+#endif
+
+	panic #$FF // XXX implement this
+
+burst_detect_fail:
+
+	rts
+
+
+#endif

c64/kernal/iec_fast/jiffydos_load.s

@@ -20,7 +20,7 @@ jiffydos_load:
 	// Timing is critical, do not allow interrupts
 	sei
 
-#if CONFIG_IEC_BLANK_SCREEN
+#if CONFIG_IEC_JIFFYDOS_BLANK
 
 	// Preserve register with screen status (blank/visibe)
 	lda VIC_SCROLY
@@ -57,7 +57,7 @@ jiffydos_load_loop:
 	lda CIA2_PRA
 	and #$FF - BIT_CIA2_PRA_DAT_OUT    // release
 
-#if CONFIG_IEC_BLANK_SCREEN
+#if CONFIG_IEC_JIFFYDOS_BLANK
 
 	// It seems JiffyDOS needs some time here; waste few cycles
 	nop
@@ -143,7 +143,7 @@ jiffydos_load_end:
 	lda #$01
 	sta IECPROTO
 
-#if CONFIG_IEC_BLANK_SCREEN
+#if CONFIG_IEC_JIFFYDOS_BLANK
 
 	// Restore screen state
 	lda TBTCNT

c64/kernal/init/fda3.ioinit.s

@@ -110,8 +110,6 @@ IOINIT:
 	lda #$3F
 	sta CIA2_DDRA    // $DD02
 
-	// XXX detect TOD clock, see  https://codebase64.org/doku.php?id=base:efficient_tod_initialisation
-
 	// XXX how to initialize these timers???
 	// stx CIA1_CRB    // $DC0F
 	// stx CIA2_CRA    // $DD0E
@@ -123,13 +121,8 @@ IOINIT:
 	ldx #%00000111 // XXX adapt this to IEC idle state, JMP at the end won't be needed
 	stx CIA2_PRA    // $DD00
 
-	// 
+	// Put something sane in the IRQ timer
-
+	jsr setup_irq_timer
-	ldy #<16421
-	ldx #>16421
-
-	sty CIA1_TIMALO    // $DC04
-	stx CIA1_TIMAHI    // $DC05
 
 	// Enable timer A to run continuously (http://codebase64.org/doku.php?id=base:timerinterrupts)
 	ldx #$11

c64/kernal/init/setup_pal_ntsc.s

@@ -23,43 +23,39 @@ setup_pal_ntsc:
 
 setup_pal:
 
-	// Set timer interval to ~1/60th of a second
-
-	// (This value was calculated by running a custom IRQ handler on a C64
-	// with original KERNAL, and writing the values of $DC04/5 to the screen
-	// in the IRQ handler to see roughly what value the timers must be set to)
-	// ldy #<16380
-	// ldx #>16380
-
-	// PAL C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
-	// is clocked at 0.985248 MHz, so that 1/60s is 16421 ($4025) CPU cycles
-
-	ldy #<16421
-	ldx #>16421
-
 	lda #$01
+	skip_2_bytes_trash_nvz
+
+	// FALLTROUGH
+
+setup_ntsc:
+
+	lda #$00
 
 	// FALLTROUGH
 
 setup_pal_ntsc_end:
 
-	sty CIA1_TIMALO    // $DC04
-	stx CIA1_TIMAHI    // $DC05
-
 	sta TVSFLG
 
+	// FALLTROUGH
+
+setup_irq_timer: // entry point needed by UP9600 and CIA1 burst mod support
+
+	// Sets up IRQ timer in CIA1 to ~1/60th of a second,
+	// depending on the detected video system
+
+	// Retrieve video system (0 - NTSC, 1 - PAL), assume PAL for unknown values
+
+	ldx TVSFLG
+	beq !+
+	ldx #$01
+!:
+	// Setup interval for timer A in CIA1
+
+	lda irq_timing_lo, x
+	sta CIA1_TIMALO                    // $DC04
+	lda irq_timing_hi, x
+	sta CIA1_TIMAHI                    // $DC05
+
 	rts
-
-setup_ntsc:
-
-	// Set timer interval to ~1/60th of a second
-	
-	// NTSC C64 (https://codebase64.org/doku.php?id=base:cpu_clocking),
-	// is clocked at 1.022727 MHz, so that 1/60s is 17045 ($4295) CPU cycles
-
-	ldy #<17045
-	ldx #>17045
-
-	lda #$00
-
-	beq setup_pal_ntsc_end // branch always