From 85adb811bbe39486e822715691325691065cf512 Mon Sep 17 00:00:00 2001
From: Wayne Warthen <wwarthen@gmail.com>
Date: Sat, 22 Jan 2022 17:15:07 -0800
Subject: [PATCH] Add CTC Hardware Detection

---
 Source/HBIOS/Config/MBC_std.asm |  2 -
 Source/HBIOS/cfg_mbc.asm        |  2 +-
 Source/HBIOS/ctc.asm            | 70 ++++++++++++++++++++++++++++-----
 Source/ver.inc                  |  2 +-
 Source/ver.lib                  |  2 +-
 5 files changed, 64 insertions(+), 14 deletions(-)

diff --git a/Source/HBIOS/Config/MBC_std.asm b/Source/HBIOS/Config/MBC_std.asm
index ce2106b2..8d9fec06 100644
--- a/Source/HBIOS/Config/MBC_std.asm
+++ b/Source/HBIOS/Config/MBC_std.asm
@@ -37,5 +37,3 @@ PPIDEENABLE	.SET	TRUE		; PPIDE: ENABLE PARALLEL PORT IDE DISK DRIVER (PPIDE.ASM)
 ;
 DSKYENABLE	.SET	FALSE		; ENABLES DSKY
 DSKYMODE	.SET	DSKYMODE_NG	; DSKY VERSION: DSKYMODE_[V1|NG]
-;
-CTCENABLE	.SET	FALSE		; ENABLE ZILOG CTC SUPPORT
diff --git a/Source/HBIOS/cfg_mbc.asm b/Source/HBIOS/cfg_mbc.asm
index ef403af0..08547480 100644
--- a/Source/HBIOS/cfg_mbc.asm
+++ b/Source/HBIOS/cfg_mbc.asm
@@ -41,7 +41,7 @@ RTCIO		.EQU	$70		; RTC LATCH REGISTER ADR
 KIOENABLE	.EQU	FALSE		; ENABLE ZILOG KIO SUPPORT
 KIOBASE		.EQU	$80		; KIO BASE I/O ADDRESS
 ;
-CTCENABLE	.EQU	FALSE		; ENABLE ZILOG CTC SUPPORT
+CTCENABLE	.EQU	TRUE		; ENABLE ZILOG CTC SUPPORT
 CTCDEBUG	.EQU	FALSE		; ENABLE CTC DRIVER DEBUG OUTPUT
 CTCBASE		.EQU	$B0		; CTC BASE I/O ADDRESS
 CTCTIMER	.EQU	TRUE		; ENABLE CTC PERIODIC TIMER
diff --git a/Source/HBIOS/ctc.asm b/Source/HBIOS/ctc.asm
index b7be79e6..9d0d69f7 100644
--- a/Source/HBIOS/ctc.asm
+++ b/Source/HBIOS/ctc.asm
@@ -19,17 +19,27 @@ CTC_TIMCFG	.EQU	%11010111	; CTC TIMER CHANNEL CONFIG
 		;	 |+-------- COUNTER MODE
 		;	 +--------- INTERRUPT ENABLE
 ;
-#IF (CTCTIMER)
+#IF (INTMODE != 2)
+	.ECHO	"*** WARNING: CTC TIMER DISABLED -- INTMODE 2 REQUIRED!!!\n"
+#ENDIF
+;
+#IF (CTCTIMER & (INTMODE == 2))
+;
+  #IF (INT_CTC0A % 4)
+  
+	.ECHO	INT_CTC0A
+	.ECHO	"\n"
+	.ECHO	(INT_CTC0A % 4)
+	.ECHO	"\n"
+  
+	.ECHO	"*** ERROR: CTC BASE VECTOR NOT /4 ALIGNED!!!\n"
+	!!!	; FORCE AN ASSEMBLY ERROR
+  #ENDIF
 ;
 ; ONLY IM2 IMPLEMENTED BELOW.  I DON'T SEE ANY REASONABLE WAY TO
 ; IMPLEMENT AN IM1 TIMER BECAUSE THE CTC PROVIDES NO WAY TO
 ; DETERMINE IF IT WAS THE CAUSE OF AN INTERRUPT OR A WAY TO
 ; DETERMINE WHICH CHANNEL CAUSED AN INTERRUPT.
-;
-  #IF (INTMODE != 2)
-	.ECHO	"*** ERROR: CTC REQUIRES INTMODE 2!!!\n"
-	!!!	; FORCE AN ASSEMBLY ERROR
-  #ENDIF
 ;  
 CTC_PREIO	.EQU	CTCBASE + CTCPRECH
 CTC_SCLIO	.EQU	CTCBASE + CTCTIMCH
@@ -82,6 +92,9 @@ CTCTIVT		.EQU	INT_CTC0A + CTCTIMCH
 ;
 ;
 CTC_PREINIT:
+	CALL	CTC_DETECT		; DO WE HAVE ONE?
+	LD	(CTC_EXIST),A		; SAVE IT
+	RET	NZ			; ABORT IF NONE
 ;
 	; RESET ALL CTC CHANNELS
 	LD	B,4			; 4 CHANNELS
@@ -92,7 +105,7 @@ CTC_PREINIT1:
 	INC	C			; NEXT CHANNEL PORT
 	DJNZ	CTC_PREINIT1
 ;
-#IF (CTCTIMER)
+#IF (CTCTIMER & (INTMODE == 2))
 	; SETUP TIMER INTERRUPT IVT SLOT
 	LD	HL,HB_TIMINT		; TIMER INT HANDLER ADR
 	LD	(IVT(CTCTIVT)),HL	; IVT ENTRY FOR TIMER CHANNEL
@@ -136,9 +149,20 @@ CTC_PRTCFG:
 	LD	A,CTCBASE		; GET BASE PORT
 	CALL	PRTHEXBYTE		; PRINT BASE PORT
 ;
-#IF (CTCTIMER)
+	LD	A,(CTC_EXIST)		; IS IT THERE?
+	OR	A			; 0 MEANS YES
+	JR	Z,CTC_PRTCFG1		; IF SO, CONTINUE
+;
+	; NOTIFY NO CTC HARDWARE
+	PRTS(" NOT PRESENT$")
+	OR	$FF
+	RET
+;
+CTC_PRTCFG1:
 ;
-	PRTS(" MODE=$")			; FORMATTING
+#IF (CTCTIMER & (INTMODE == 2))
+;
+	PRTS(" TIMER MODE=$")			; FORMATTING
   #IF (CTCMODE == CTCMODE_CTR)
 	PRTS("CTR$")
   #ENDIF
@@ -175,3 +199,31 @@ CTC_PRTCFG:
 ;
 	XOR	A
 	RET
+;
+;
+;
+CTC_DETECT:
+	LD	A,CTC_TIM256CFG
+	OUT	(CTCBASE),A
+	XOR	A
+	OUT	(CTCBASE),A
+	; CTC SHOULD NOW BE RUNNING WITH TIME CONSTANT 0
+	LD	A,CTC_TIM256CFG		; RESET
+	OUT	(CTCBASE),A
+	IN	A,(CTCBASE)		; SHOULD READ 0 NOW
+	CP	0
+	JR	NZ,CTC_NO
+	LD	A,$FF			; TIME CONSTANT $FF
+	OUT	(CTCBASE),A
+	IN	A,(CTCBASE)		; SHOULD NOT BE 0 NOW
+	CP	0
+	JR	Z,CTC_NO
+	XOR	A
+	RET
+CTC_NO:
+	OR	$FF
+	RET
+;
+;
+;
+CTC_EXIST	.DB	$FF	
diff --git a/Source/ver.inc b/Source/ver.inc
index b3061a4a..1176d907 100644
--- a/Source/ver.inc
+++ b/Source/ver.inc
@@ -2,4 +2,4 @@
 #DEFINE	RMN	1
 #DEFINE	RUP	1
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.1.1-pre.147"
+#DEFINE BIOSVER	"3.1.1-pre.148"
diff --git a/Source/ver.lib b/Source/ver.lib
index ade54c98..496282d8 100644
--- a/Source/ver.lib
+++ b/Source/ver.lib
@@ -3,5 +3,5 @@ rmn	equ	1
 rup	equ	1
 rtp	equ	0
 biosver	macro
-	db	"3.1.1-pre.147"
+	db	"3.1.1-pre.148"
 	endm