Added division routine. Removed C callable entry points from mul routines,

they're now in common. git-svn-id: svn://svn.cc65.org/cc65/trunk@4441 b7a2c559-68d2-44c3-8de9-860c34a00d81
2009-11-04 18:23:40 +00:00
parent 851926b301
commit c200e0ec94
4 changed files with 59 additions and 15 deletions
--- a/libsrc/runtime/udiv32by16r16.s
+++ b/libsrc/runtime/udiv32by16r16.s
@@ -0,0 +1,55 @@
+;
+; Ullrich von Bassewitz, 2009-11-04
+;
+; CC65 runtime: 32by16 => 16 unsigned division
+;
+
+       	.export	       	udiv32by16r16, udiv32by16r16m
+ 	.importzp   	ptr1, ptr2, ptr3, sreg
+
+
+;---------------------------------------------------------------------------
+; 32by16 division. Divide ptr1:ptr2 by ptr3. Result is in ptr1, remainder
+; in sreg.
+;
+;   lhs         rhs           result      result also in    remainder
+; -----------------------------------------------------------------------
+;   ptr1:ptr2   ptr3          ax          ptr1              sreg
+;
+
+
+udiv32by16r16:
+        sta     ptr3
+        stx     ptr3+1
+udiv32by16r16m:
+        lda    	#0
+ 	sta	sreg+1
+ 	ldy	#32
+
+L0:    	asl     ptr1
+        rol     ptr1+1
+        rol     ptr2
+        rol     ptr2+1
+        rol     a
+        rol     sreg+1
+
+ 	pha
+ 	cmp	ptr3
+ 	lda	sreg+1
+ 	sbc	ptr3+1
+ 	bcc	L1
+
+ 	sta	sreg+1
+ 	pla
+ 	sbc	ptr3
+ 	pha
+ 	inc	ptr1
+
+L1:	pla
+ 	dey
+ 	bne	L0
+ 	sta	sreg
+        lda     ptr1
+        ldx     ptr1+1
+ 	rts
+