X-Git-Url: http://cloudbase.mooo.com/gitweb/z180-stamp-cpm3.git/blobdiff_plain/8e627f7e15efe9910f48944cb490b4e46e4a50d8..b43b466252b6733ba9d76a5858d5afa2a6313ad1:/cbios/misc.180

diff --git a/cbios/misc.180 b/cbios/misc.180
index 0352a59..b7fee3f 100644
--- a/cbios/misc.180
+++ b/cbios/misc.180
@@ -1,5 +1,5 @@
 
-	global add_hla,div32_16
+	global add_hla,div32_16,div32_r
 	global ioiniml,ioini1l
 	global intinit
 	global bufinit
@@ -13,8 +13,8 @@
 	include config.inc
 	include	z180reg.inc
 
-;--------------------------------------------------------------
-;
+
+;--------------------------------------------------------------------
 ; add a to hl
 ;
 ;    return:
@@ -30,14 +30,36 @@ add_hla:
 	inc	h
 	ret
 
+;--------------------------------------------------------------------
+; rounded div 32 by 16 bit
+;
+;	HLDE:	Dividend (x)
+;	BC:	Divisor  (y)
+;    return:
+;	HLDE: 	Rounded Quotient (q)
+;	BC:   	Remainder	       (r)
+
+	cseg
+
+div32_r:
+	push bc
+	srl	b		;y/2
+	rr	c
+	add	hl,bc		;low x + y/2
+	pop	bc
+	jr	nc,div_r1
+	inc	hl
+div_r1:
+	;fall thru
+
 ;--------------------------------------------------------------------
 ; Divide 32 bit by 16
 ;
-;    HLDE:	Divident (x)
+;    DEHL:	Dividend (x)
 ;    BC:	Divisor  (y)
 ;
 ;  return:
-;    HLDE:	Quotient
+;    DEHL:	Quotient
 ;    BC:	Reminder
 
 	cseg	; common area
@@ -46,26 +68,25 @@ div32_16:
 	push	de		;save alternate registers (de,bc)
 	push	bc
 	exx			;high
-	push	de		;low x
-	push	bc		;low y
-	ld	bc,0		;bc  = high y = 0
-	ld	d,b		;de  = high r = 0
-	ld	e,c
-	ex	de,hl		;de = x, hl = r
+	push	hl		;lx
+	push	bc		;ly
+	ld	bc,0		;bc  = hy = 0
+	ld	h,b		;hl  = hr = 0
+	ld	l,c
+				;de = x, hl = r
 	exx			;low
-	pop	bc		;bc' = low y
-	ex	(sp),hl		;hl' = low x, save alternate hl
-	ld	de,0		;de' = low r = 0
+	pop	bc		;bc' = ly
+	ex	(sp),hl		;hl' = lx, save alternate hl
+	ld	de,0		;de' = lr = 0
 	ex	de,hl		;de = x, hl = r
 	exx			;high
 	ld	a,32		;count
 ;
-; divide x/y
-;     x: hl
-;     y: de
-;   result:
-;     x/y: hl
-;     rem: de
+; start:
+;     de: x	(de: hx, de': lx)
+;     bc: y	(bc: hy, bc': ly)
+;     hl: 0
+;
 div_lp:				;do
 	exx			;    low
 	ex	de,hl		;    x
@@ -96,15 +117,18 @@ div_no_restore:			;
 	dec	a		;
 	jr	nz,div_lp	;while (--count)
 
-	ex	de,hl		; q
+; result:
+;     de: q	(de: hq, de': lq)
+;     hl: r	(hl: hr, hl': lr)
+
 	exx			;low
-	ex	de,hl		; q
+	ex	de,hl		;hl = lq,  de = lr
 
-	ex	(sp),hl		;low q
-	push	de		;low r
+	ex	(sp),hl		;lq
+	push	de		;lr
 	exx			;high
-	pop	bc		;bc = r
-	pop	de		;de = low q
+	pop	bc		;bc = lr
+	pop	hl		;de = lq
 
 	exx			;low
 	pop	bc		;restore alternate registers
@@ -253,8 +277,8 @@ cpu_frq:
 	ld	d,h
 	ld	e,l
 	call	get_timer
-	push	hl
 	push	de
+	push	hl
 
 ; delay  ~8ms @ 18.432MHz  --> 147456 clock cycles
 ; delay ~10ms @ 18.432MHz  --> 184320 clock cycles
@@ -268,21 +292,16 @@ dly_lp:
 	sbc	hl,de		; 10
 	jr	nz,dly_lp	; 6/8  -> 18
 
-	pop	de
 	pop	hl
+	pop	de
 	call	get_timer
 
-;	ld	hl,4		; round
-	ld	hl,5		; round
-	add	hl,de
-	ex	de,hl
-	ld	hl,0
 	ld	bc,10
-	call	div32_16
-	ld	b,d
-	ld	c,e
-	ld	hl,00119h	;18432000/(2**16)
-	ld	de,04000h	;18432000%(2**16)
+	call	div32_r
+	ld	b,h
+	ld	c,l
+	ld	de,00119h	;18432000/(2**16)
+	ld	hl,04000h	;18432000%(2**16)
 
 	ld	a,b
 	or	a
@@ -291,15 +310,15 @@ dly_lp:
 	cp	2
 	jr	c,cpuf_done
 cpuf_div:
-	call	div32_16
+	call	div32_r
 cpuf_done:
 	ret
 
 ;--------------------------------------------------------------------
 
 get_timer:
-	push	hl
 	push	de
+	push	hl
 	ld	hl,1*256 + 3		; d = subcommand, e = command
 	push	hl
 	ld	hl,0
@@ -315,8 +334,8 @@ get_timer:
 
 	pop	bc
 	inc	sp
-	pop	de
 	pop	hl
+	pop	de
 	ret
 
 ;--------------------------------------------------------------------