Workaround Z280 CPU Bug for LZSA2

The LZSA2 decompressor invoked a known Z280 CPU bug.  A small modification to the code resolves this.

Doc/ChangeLog.txt

@@ -5,6 +5,7 @@ Version 3.3
 - A?C: Support for SD PIO
 - A?C: Support for Z80-Retro SD interface
 - WBW: Support per-drive floppy configuration
+- WBW: Support for Bill Shen's VGARC
 
 Version 3.2.1
 -------------

Source/Doc/UserGuide.md

@@ -3808,6 +3808,7 @@ the RomWBW HBIOS configuration.
    - WDC Floppy Disk Controller w/ 3.5" HD Drives
    - Onboard IDE Hard Disk Interface Module
    - PPIDE Hard Disk Interface Module
+   - VGARC Video & Keyboard Module
  - Serial baud rate is usually determined by hardware for ACIA and
    SIO interfaces
 
@@ -3831,6 +3832,7 @@ the RomWBW HBIOS configuration.
    - WDC Floppy Disk Controller w/ 3.5" HD Drives
    - Onboard IDE Hard Disk Interface Module
    - PPIDE Hard Disk Interface Module
+   - VGARC Video & Keyboard Module
  - Serial baud rate is usually determined by hardware for ACIA and
    SIO interfaces
 
@@ -3854,6 +3856,7 @@ the RomWBW HBIOS configuration.
    - WDC Floppy Disk Controller w/ 3.5" HD Drives
    - Onboard IDE Hard Disk Interface Module
    - PPIDE Hard Disk Interface Module
+   - VGARC Video & Keyboard Module
  - Serial baud rate is usually determined by hardware for ACIA and
    SIO interfaces
 
@@ -3923,6 +3926,6 @@ may be discovered by RomWBW in your system.
 | USB-FIFO  | Char     | FT232H-based ECB USB FIFO                              |
 | VDU       | Video    | MC6845 Family Video Display Controller                 |
 | VGA       | Video    | HD6445CP4-based Video Display Controller               |
-| VRC       | Video    | VGARC Video Display Controller                        s |
+| VRC       | Video    | VGARC Video Display Controller                         |
 | YM        | Audio    | YM2612 Programmable Sound Generator                    |
 | Z2U       | Char     | Zilog Z280 CPU Built-in Serial Ports                   |

Source/Fonts/Build.cmd

@@ -11,8 +11,8 @@ echo Preparing compressed font files...
 lzsa -f2 -r font8x8u.bin font8x8c.bin || exit /b
 lzsa -f2 -r font8x11u.bin font8x11c.bin || exit /b
 lzsa -f2 -r font8x16u.bin font8x16c.bin || exit /b
-
 lzsa -f2 -r fontcgau.bin fontcgac.bin || exit /b
+lzsa -f2 -r fontvgarcu.bin fontvgarcc.bin || exit /b
 
 fonttool font8x8u.bin > font8x8u.asm || exit /b
 fonttool font8x11u.bin > font8x11u.asm || exit /b
@@ -20,6 +20,7 @@ fonttool font8x16u.bin > font8x16u.asm || exit /b
 fonttool font8x8c.bin > font8x8c.asm || exit /b
 fonttool font8x11c.bin > font8x11c.asm || exit /b
 fonttool font8x16c.bin > font8x16c.asm || exit /b
-
 fonttool fontcgau.bin > fontcgau.asm || exit /b
 fonttool fontcgac.bin > fontcgac.asm || exit /b
+fonttool fontvgarcu.bin > fontvgarcu.asm || exit /b
+fonttool fontvgarcc.bin > fontvgarcc.asm || exit /b

Source/Fonts/Makefile

@@ -1,8 +1,8 @@
 OBJECTS = \
-	font8x8u.asm font8x11u.asm font8x16u.asm fontcgau.asm \
-	font8x8c.asm font8x11c.asm font8x16c.asm fontcgac.asm
+	font8x8u.asm font8x11u.asm font8x16u.asm fontcgau.asm fontvgarcu.asm \
+	font8x8c.asm font8x11c.asm font8x16c.asm fontcgac.asm fontvgarcc.asm
 
-OTHERS = font8x8c.bin font8x11c.bin font8x16c.bin fontcgac.bin
+OTHERS = font8x8c.bin font8x11c.bin font8x16c.bin fontcgac.bin fontvgarcc.bin
 
 TOOLS = ../../Tools
 
@@ -26,5 +26,8 @@ font8x16c.bin: font8x16u.bin
 fontcgac.bin: fontcgau.bin
 	$(BINDIR)/lzsa -f2 -r $< $@
 
+fontvgarcc.bin: fontvgarcu.bin
+	$(BINDIR)/lzsa -f2 -r $< $@
+
 %.asm: %.bin
 	$(BINDIR)/bin2asm $< > $@

Source/HBIOS/Makefile

@@ -24,7 +24,8 @@ endif
 
 include $(TOOLS)/Makefile.inc
 
-FONTS := font8x11c.asm font8x11u.asm font8x16c.asm font8x16u.asm font8x8c.asm font8x8u.asm fontcgac.asm fontcgau.asm
+FONTS := font8x11c.asm font8x11u.asm font8x16c.asm font8x16u.asm font8x8c.asm font8x8u.asm \
+	fontcgac.asm fontcgau.asm fontvgarcc.asm fontvgarcu.asm
 
 ifeq ($(CPUFAM),2)
 	TASM=$(BINDIR)/uz80as -t hd64180

Source/HBIOS/cfg_rcz280.asm

@@ -20,7 +20,7 @@ CPUFAM		.EQU	CPU_Z280	; CPU FAMILY: CPU_[Z80|Z180|Z280]
 BIOS		.EQU	BIOS_WBW	; HARDWARE BIOS: BIOS_[WBW|UNA]
 BATCOND		.EQU	FALSE		; ENABLE LOW BATTERY WARNING MESSAGE
 HBIOS_MUTEX	.EQU	FALSE		; ENABLE REENTRANT CALLS TO HBIOS (ADDS OVERHEAD)
-USELZSA2	.EQU	FALSE		; ENABLE FONT COMPRESSION
+USELZSA2	.EQU	TRUE		; ENABLE FONT COMPRESSION
 TICKFREQ	.EQU	50		; DESIRED PERIODIC TIMER INTERRUPT FREQUENCY (HZ)
 ;
 BOOT_TIMEOUT	.EQU	-1		; AUTO BOOT TIMEOUT IN SECONDS, -1 TO DISABLE, 0 FOR IMMEDIATE

Source/HBIOS/hbios.asm

@@ -6225,6 +6225,16 @@ FONTCGA:
 	.ECHO	" CGA"
 #ENDIF
 ;
+#IFDEF USEFONTVGARC
+FONTVGARC:
+  #IF USELZSA2
+    #INCLUDE "fontvgarcc.asm"
+  #ELSE
+    #INCLUDE "fontvgarcu.asm"
+  #ENDIF
+	.ECHO	" VGARC"
+#ENDIF
+;
 SIZ_FONTS	.EQU	$ - ORG_FONTS
 		.ECHO	" occupy "
 		.ECHO	SIZ_FONTS

Source/HBIOS/unlzsa2s.asm

@@ -60,8 +60,8 @@
 ;  3. This notice may not be removed or altered from any source distribution.
 ;
 
-;	#DEFINE	BACKWARD_DECOMPRESS						; uncomment for data compressed with option -b (+5 bytes, -3% speed)
-;	#DEFINE	AVOID_SELFMODIFYING_CODE					; uncomment to disallow self-modifying code (-1 byte, -4% speed)
+;	#DEFINE	BACKWARD_DECOMPRESS		; uncomment for data compressed with option -b (+5 bytes, -3% speed)
+;	#DEFINE	AVOID_SELFMODIFYING_CODE	; uncomment to disallow self-modifying code (-1 byte, -4% speed)
 
 	#IFNDEF	BACKWARD_DECOMPRESS
 
@@ -79,7 +79,7 @@
 
 		#DEFINE ADD_OFFSET \
 		#DEFCONT \ ld a,e \ sub l \ ld l,a
-		#DEFCONT \ ld a,d \ sbc h \ ld h,a						; 6*4 = 24t / 6 bytes
+		#DEFCONT \ ld a,d \ sbc h \ ld h,a	; 6*4 = 24t / 6 bytes
 
 		#DEFINE BLOCKCOPY \
 		#DEFCONT \ lddr
@@ -118,7 +118,7 @@ MatchLen:		and %00000111 \ add a,2 \ cp 9
 			call z,ExtendedCode
 
 CopyMatch:		ld c,a
-			push hl						; BC = len, DE = dest, HL = -offset, SP -> [src]
+			push hl		; BC = len, DE = dest, HL = -offset, SP -> [src]
 
 	#IFNDEF	AVOID_SELFMODIFYING_CODE
 PrevOffset		.EQU $+1 \ ld hl,0
@@ -126,8 +126,8 @@ PrevOffset		.EQU $+1 \ ld hl,0
 			push ix \ pop hl
 	#ENDIF
 			ADD_OFFSET
-			BLOCKCOPY					; BC = 0, DE = dest
-			pop hl						; HL = src
+			BLOCKCOPY	; BC = 0, DE = dest
+			pop hl		; HL = src
 
 ReadToken:	ld a,(hl) \ NEXT_HL \ push af
 		and %00011000 \ jr z,NoLiterals
@@ -163,12 +163,16 @@ ExtendedCode:	call ReadNibble \ inc a \ jr z,ExtraByte
 ExtraByte	ld a,15 \ add a,c \ add a,(hl) \ NEXT_HL \ ret nc
 		ld a,(hl) \ NEXT_HL
 		ld b,(hl) \ NEXT_HL \ ret nz
-		pop bc								; RET is not needed, because RET from ReadNibble is sufficient
+		pop bc			; RET is not needed, because RET from ReadNibble is sufficient
 
 
 ReadNibble:	ld c,a
-skipLDCA	xor a \ ex af,af' \ ret m
+skipLDCA	xor a \ nop \ ex af,af' \ ret m		; NOP for Z280 bug
 		ld a,(hl) \ or $F0 \ ex af,af'
 		ld a,(hl) \ NEXT_HL \ or $0F
 		rrca \ rrca \ rrca \ rrca \ ret
 
+; The extraneous NOP instruction above is to workaround a bug in the
+; Z280 processor where ex af,af' can copy rather than swap the flags
+; register.
+; See https://www.retrobrewcomputers.org/forum/index.php?t=msg&goto=10183&

Source/HBIOS/vrc.asm

@@ -21,8 +21,8 @@ VRC_KBDST	.EQU	$F5
 VRC_ROWS	.EQU	48
 VRC_COLS	.EQU	64
 ;
-#DEFINE USEFONT8X8
-#DEFINE	VRC_FONT FONT8X8
+#DEFINE USEFONTVGARC
+#DEFINE	VRC_FONT FONTVGARC
 ;
 TERMENABLE	.SET	TRUE		; INCLUDE TERMINAL PSEUDODEVICE DRIVER
 ;
@@ -283,9 +283,14 @@ VRC_LOADFONT:
 	LD	HL,VRC_FONT		; START OF FONT DATA
 #ENDIF
 ;
+#IF 0
+	; THIS APPROACH TO LOADING FONTS IS BEST (FASTEST), BUT IS
+	; CAUSING ARTIFACTS ON THE DISPLAYED FONTS WHEN RUN ON A
+	; Z280.  IT IS NOT CLEAR WHAT THE PROBLEM IS (POSSIBLY
+	; Z280 BUG), BUT FOR NOW WE AVOID THIS AND USE AN
+	; ALTERNATIVE APPROACH BELOW.
 	LD	DE,0+(128*8)-1		; LENGTH OF FONT DATA - 1
 	ADD	HL,DE			; ADD TO HL
-;	LD	HL,ENDFONT-1
 	LD	BC,VRC_FONTBASE+3	; WORK BACKWARDS
 	OTDR				; DO 4 PAGES
 	DEC	C
@@ -295,6 +300,24 @@ VRC_LOADFONT:
 	DEC	C
 	OTDR
 	DEC	C
+#ENDIF
+;
+#IF 1
+	; ALTERNATIVE APPROACH TO LOADING FONTS.  THIS ONE AVOIDS
+	; THE USE OF OTDR WHICH SEEMS TO CAUSE PROBLEMS ON Z280.
+	LD	B,0
+	LD	C,VRC_FONTBASE
+VRC_LOADFONT1:
+	LD	A,(HL)
+	OUT	(C),A
+	INC	HL
+	INC	B
+	JR	NZ,VRC_LOADFONT1
+	INC	C
+	LD	A,C
+	CP	VRC_FONTBASE + 4
+	JR	NZ,VRC_LOADFONT1
+#ENDIF
 ;
 #IF USELZSA2
 	LD	HL,(VRC_STACK)		; ERASE DECOMPRESS BUFFER

Source/ver.inc

@@ -2,7 +2,7 @@
 #DEFINE	RMN	3
 #DEFINE	RUP	0
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.3.0-dev.10"
+#DEFINE BIOSVER	"3.3.0-dev.12"
 #define rmj	RMJ
 #define rmn	RMN
 #define rup	RUP

Source/ver.lib

@@ -3,5 +3,5 @@ rmn	equ	3
 rup	equ	0
 rtp	equ	0
 biosver	macro
-	db	"3.3.0-dev.10"
+	db	"3.3.0-dev.12"
 	endm