Optimize a negation in signed division.

2019-11-05 20:15:34 +01:00 · 2019-11-05 20:15:34 +01:00 · 2bec637637
parent 0d21a2b5a4
commit 2bec637637
1 changed files with 5 additions and 6 deletions
--- a/libsrc/runtime/idiv32by16r16.s
+++ b/libsrc/runtime/idiv32by16r16.s
@ -29,19 +29,18 @@ idiv32by16r16:
        stx     ptr3+1

        lda     ptr2+1
+        cmp     #$80
        eor     tmp1
        sta     tmp1
-        bit     ptr2+1
-        bpl     @L3
+        bcc     @L3

 ; Negate the value in ptr1:ptr2

        ldx     #0
        ldy     #4
-        sec
-@L2:    lda     ptr1,x
-        eor     #$FF
-        adc     #$00
+;       sec
+@L2:    lda     #$00
+        sbc     ptr1,x
        sta     ptr1,x
        inx
        dey