From 2fa1a7069a9709f8d61a198cec1b1d9b2e275fe1 Mon Sep 17 00:00:00 2001
From: Leo C
Date: Tue, 5 May 2015 15:42:49 +0200
Subject: Z180 banking updates

---
 z180/init.180 | 191 +++++++++++++++++++++-------------------------------------
 1 file changed, 70 insertions(+), 121 deletions(-)

(limited to 'z180/init.180')

diff --git a/z180/init.180 b/z180/init.180
index 73a77bb..f43aaeb 100644
--- a/z180/init.180
+++ b/z180/init.180
@@ -234,51 +234,6 @@ buf.init:
 	ld	(ix+o.mask),a
 	ret
 
-;----------------------------------------------------------------------
-if 0
-	extrn	msginit,msg_tx_fifo,msg_rx_fifo
-	extrn	msg.sout
-
-bufferinit:
-
-	ld	de,msg_tx_fifo
-	in0	a,cbr
-	call	log2phys
-	ld	(40h+0),hl
-	ld	(40h+2),a
-
-;	ld	(bufdat+1),hl
-;	ld	(bufdat+3),a
-;	ld	a,1
-;	ld	(bufdat+0),a
-;	ld	hl,inimsg
-;	call	msg.sout
-
-	ld	de,msg_rx_fifo
-	in0	a,cbr
-	call	log2phys
-	ld	(bufdat+1),hl
-	ld	(bufdat+3),a
-	ld	a,2
-	ld	(bufdat+0),a
-	ld	hl,inimsg
-	call	msg.sout
-
-	ret
-
-inimsg:
-	db	inimsg_e - $ - 1
-	db	0AEh
-	db	inimsg_e - $ - 1
-	db	0
-bufdat:
-	db	0
-	dw	0
-	db	0
-inimsg_e:
-
-endif
-
 ;----------------------------------------------------------------------
 
 	extrn	msginit,msg.sout
@@ -300,27 +255,27 @@ bfi_1:
 	inc	hl
 	ld	d,(hl)
 	inc	hl
-	push	hl
+	ex	de,hl
 
 	or	a
 	jr	nz,bfi_2
-	call	hw_log2phys
+	call	hwl2phy
 	ld	(40h+0),hl
 	ld	(40h+2),a
-	out0	(AVRINT5),a
+	out	(AVRINT5),a
 	jr	bfi_3	
 bfi_2:
-	call	hw_log2phys
+	call	hwl2phy
 	ld	(bufdat+1),hl
 	ld	(bufdat+3),a
 	ld	hl,inimsg
 	call	msg.sout
 bfi_3:
-	pop	hl
+	ex	de,hl
 	djnz	bfi_1
 	ret
 
-    else
+    else ;CPU_Z180
 
 	call	msginit
 
@@ -340,7 +295,7 @@ bfi_1:
 	jr	nz,bfi_2
 
 	ld	a,(@cbnk)
-	call	bnk2phys
+	call	bnk2phy
 
 	ld	(40h+0),hl
 	ld	(40h+2),a
@@ -349,7 +304,7 @@ bfi_1:
 bfi_2:
 
 	ld	a,(@cbnk)
-	call	bnk2phys
+	call	bnk2phy
 
 	ld	(bufdat+1),hl
 	ld	(bufdat+3),a
@@ -548,115 +503,109 @@ io.ini.l:
 ;
     if CPU_Z180
 
-; a: Bank number
+;--------------------------------------------------------------------
+; Return the BBR value for the given bank number
 ;
+; in  a: Bank number
 ; out a: bbr value
 
 bnk2log:
-	push	bc
-	ld	b,a
-	ld	c,CA
-	mlt	bc
-	add	a,10h
-	pop	bc
-	ret
+	or	a		;
+	ret	z		; Bank 0 is at physical address 0
 
-; de: Log. Address
-;  a: Bank number
+	push	bc		;
+	ld	b,a		;
+	ld	c,CA		;
+	mlt	bc		;
+	ld	a,c		;
+	add	a,10h		;
+	pop	bc		;
+	ret			;
+
+;--------------------------------------------------------------
+
+;in  hl: Log. Address
+;     a: Bank number
 ;
 ;out ahl: Phys. (linear) Address
 
 
-bnk2phys:
+bnk2phy:
 	call	bnk2log
-
 	; fall thru
+
 ;--------------------------------------------------------------
 ;
-; de: Log. Address
+; hl: Log. Address
 ;  a: Bank base (bbr)
 ;
-; OP: ahl = (a<<12) + (d<<8) + e
+;	     2           0       0
+;	     0   6       8       0
+; hl	          hhhhhhhhllllllll
+;  a	+     bbbbbbbb
+;
+; OP: ahl = (a<<12) + (h<<8) + l
 ;
 ;out ahl: Phys. (linear) Address
 
-
-log2phys:
+log2phy:
 	push	bc		;
+l2p_i:
 	ld	c,a		;
 	ld	b,16		;
-	mlt	bc		;  bc = a<<4
-	ld	l,d		;4
-	ld	h,0		;6
-	add	hl,bc		;7  bc + d == a<<4 + d
-	ld	a,h		;4
-	ld	h,l		;4
-	ld	l,e		;4
-	pop	bc		;
-	ret			;
-
-    if 0
-    
-log2phys:
-	push	bc		;
-	ld	b,a		;
-	ld	c,16		;
 	mlt	bc		; bc = a<<4
-	ld	a,c		;4
-	add	a,h		;4
-	ld	h,a		;4
-	ld	a,b		;4
-	adc	a,0		;6
+	ld	a,c		;
+	add	a,h		;
+	ld	h,a		;
+	ld	a,b		;
+	adc	a,0		;
 	pop	bc		;
 	ret			;
 
-    endif
 ;--------------------------------------------------------------
 ;
-; de: Log. Address
-; 
+; hl: Log. Address
+;
 ;
 ; OP: ahl = (bankbase<<12) + (d<<8) + e
 ;
 ;out ahl: Phys. (linear) Address
 
 
-hw_log2phys:
+hwl2phy:
 	push	bc		;
-	in0	c,(cbar)
-	ld	a,d
-	or	00fh
+	in0	c,(cbar)	;
+	ld	a,h		;
+	or	00fh		; log. addr in common1?
 	cp	c
 	jr	c,hlp_1
-	in0	c,(cbr)
-	jr	hlp_e
+
+	in0	a,(cbr)		; yes, cbr is address base
+	jr	hl2p_x
 hlp_1:
-	ld	b,16
+	ld	b,16		; log. address in baked area?
 	mlt	bc
-	ld	a,d
+	ld	a,h
 	cp	c
-	ld	c,0
-	jr	c,hlp_e
-	in0	c,(bbr)
-hlp_e:	
-	ld	b,16		;
-	mlt	bc		;bc = a<<4
-	ld	l,d		;
-	ld	h,0		;
-	add	hl,bc		;bc + d == a<<4 + d
-	ld	a,h		;
-	ld	h,l		;
-	ld	l,e		;
-	pop	bc		;
+	jr	c,hlp_2
+	in0	a,(bbr)		; yes, bbr is address base
+	jr	hl2p_x
+hlp_2:
+	xor	a		; common1
+hl2p_x:
+	jr	nz,l2p_i
+
+	pop	bc		; bank part is 0, no translation
 	ret			;
 
-    else
 
-;
+
+    else	;CPU_Z180
+
 ;----------------------------------------------------------------------
 ;
 
-bnk2phys:
+bnk2phy:
 	sla	h
 	jr	nc,b2p_1		;A15=1 --> common
 	ld	a,3
@@ -693,18 +642,18 @@ topcodsys:
 ; Save cbar
 
 isv_sw:				;
-	ex (sp),hl		;	save hl, return adr in hl
+	ex (sp),hl		;save hl, 'return adr' in hl
 	push de			;
 	push af			;
-	ex de,hl		;
+	ex de,hl		;'return address' in de
 	ld hl,0			;
 	add hl,sp		;
 	ld a,h			;
 	cp 0f8h			;
-	jr nc,isw_1		;
+	jr nc,isw_1		;stack allready in top ram
 	ld sp,$stack		;
 isw_1:
-	push hl			;
+	push hl			;save user stack pointer
 	in0 h,(cbar)		;
 	push hl			;
 	ld a,SYS$CBAR		;
-- 
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