Implement aslax7/shlax7/asrax7/shrax7

2024-01-28 21:33:12 +01:00
parent 51b946bf25
commit 7d7cf2d1e0
9 changed files with 253 additions and 0 deletions
--- a/libsrc/runtime/aslax7.s
+++ b/libsrc/runtime/aslax7.s
@@ -0,0 +1,21 @@
+;
+; Miloslaw Smyk, 2024
+;
+; CC65 runtime: Scale the primary register by 128, unsigned
+;
+
+        .export         shlax7, aslax7
+
+aslax7:
+shlax7:                         ; XXXXXXXL AAAAAAAl
+        tay
+        txa
+        lsr                     ; XXXXXXXL -> 0XXXXXXX, L->C
+        tya
+        ror                     ; AAAAAAAl -> LAAAAAAA, l->C
+        tax
+        lda     #$00            ; LAAAAAAA 00000000
+        ror                     ; LAAAAAAA l0000000
+        rts
+
+        ; 10 bytes, 16 cycles + rts