X-Git-Url: http://cloudbase.mooo.com/gitweb/z180-stamp-cpm3.git/blobdiff_plain/1d26b86661bff5609cb3ae4404a0208c1b651360..50f3b8f0cb6ccbdc5c1ea8f916f3d95b197d3d04:/cbios/mm.180?ds=sidebyside

diff --git a/cbios/mm.180 b/cbios/mm.180
index 90d8144..eb4135b 100644
--- a/cbios/mm.180
+++ b/cbios/mm.180
@@ -137,6 +137,85 @@ hl2p_x:
 	ret			;
 
 
+;--------------------------------------------------------------
+; Trampoline for routines in banked ram.
+; Switch stack pointer to "system" stack in top ram
+; Save cbar
+;
+	extrn	bs$stack
+
+	cseg	; common!
+
+	public	_b0call
+_b0call:
+
+	ld	(b0_save_hl),hl
+	ld	(b0_save_de),de
+	push	af
+	pop	hl
+	ld	(b0_save_af),hl
+
+	pop	de			;get ptr to 'function address' in de
+	ld	hl,2
+	add	hl,de
+	push	hl			;put return address on stack
+
+   if 0 ; link80
+
+	ld	hl,0
+	add	hl,sp			;
+	ld	a,h
+	cp	high (bs$stack-bs$stack$size) ;link80 can't process this
+	jr	nc,$ + 5		;skip if stack allready in common bios ram
+
+   else
+
+	ld	hl,bs$stack-bs$stack$size
+	ld	a,h
+	dec	a
+	ld	hl,0
+	add	hl,sp			;
+	cp	h
+	jr	c,$ + 5			;skip if stack allready in common bios ram
+   endif
+	ld	sp,bs$stack		;
+
+	push	hl			;save	user stack pointer
+	in0	h,(cbar)		;
+	push	hl			;
+	ld	hl,b0c_ret
+	push	hl
+	ld	a,SYS$CBAR		;
+	out0	(cbar),a		;
+	ex	de,hl			;ptr
+	ld	e,(hl)			;get 'function address'
+	inc	hl			;
+	ld	d,(hl)			;
+	push	de			;put on (switched) stack
+
+	ld	hl,(b0_save_af)		;get back users registers
+	push	hl
+	pop	af
+	ld	de,(b0_save_de)
+	ld	hl,(b0_save_hl)
+	ret				;go to function
+b0c_ret:
+	ld	(b0_save_hl),hl
+
+	pop	hl			;
+	out0	(cbar),h		;
+	pop	hl			;
+	ld	sp,hl			;
+	ld	hl,(b0_save_hl)
+	ret				;
+
+
+b0_save_hl: dw	0
+b0_save_de: dw	0
+b0_save_af: dw	0
+
+
+
 ;====================================================================
 
   if 0