Reestablished entry state of signed operation and optimized that (again).

2026-04-23 23:17:45 +00:00 · 2018-05-25 23:18:26 +02:00
parent ba5b580368
commit 8a5d1b9674
4 changed files with 74 additions and 54 deletions
@@ -0,0 +1,29 @@
+;
+; Ullrich von Bassewitz, 07.08.1998
+;
+; CC65 runtime: helper stuff for mod/div with signed ints
+;
+
+; When negating values, we will ignore the possibility here, that one of the
+; values is $8000, in which case the negate will fail.
+
+        .export         popsargsudiv16
+        .import         negax, popax, udiv16
+        .importzp       tmp1, tmp2, ptr1, ptr4
+
+popsargsudiv16:
+        stx     tmp2            ; Remember sign
+        cpx     #0
+        bpl     L1
+        jsr     negax           ; Negate accumulator
+L1:     sta     ptr4
+        stx     ptr4+1          ; Save right operand
+
+        jsr     popax
+        stx     tmp1            ; Remember sign
+        cpx     #0
+        bpl     L2
+        jsr     negax
+L2:     sta     ptr1
+        stx     ptr1+1
+        jmp     udiv16            ; Call the division