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/asrax7.s
+++ b/libsrc/runtime/asrax7.s
@@ -0,0 +1,18 @@
+;
+; Miloslaw Smyk, 2024
+;
+; CC65 runtime: Scale the primary register by 128, signed
+;
+
+        .export         asrax7
+
+asrax7:                         ; HXXXXXXL hAAAAAAl
+        asl                     ;          AAAAAAA0, h->C
+        txa
+        rol                     ;          XXXXXXLh, H->C
+        ldx     #$00            ; 00000000 XXXXXXLh
+        bcc     :+
+        dex                     ; 11111111 XXXXXXLh if C
+:       rts
+
+        ; 12 cycles max, 9 bytes