feat: add hMirror lib

Author: boriel

src/lib/arch/zx48k/stdlib/hmirror.bas

@@ -0,0 +1,22 @@
+#pragma once
+
+Function fastcall hMirror(number as uByte) as uByte
+    Asm
+    ;17 bytes and 66 clock cycles
+        ld b,a       ;b=ABCDEFGH
+        rrca         ;a=HABCDEFG
+        rrca         ;a=GHABCDEF
+        xor b
+        and %10101010
+        xor b        ;a=GBADCFEH
+        ld b,a       ;b=GBADCFEH
+        rrca         ;a=HGBADCFE
+        rrca         ;a=EHGBADCF
+        rrca         ;a=FEHGBADC
+        rrca         ;a=CFEHGBAD
+        xor b
+        and %01100110
+        xor b        ;a=GFEDCBAH
+        rrca         ;a=HGFEDCBA
+    End Asm
+End Function

src/lib/arch/zxnext/stdlib/hmirror.bas

@@ -0,0 +1,6 @@
+#pragma once
+
+#define hMirror(x) \
+  Asm \
+  mirror a \
+  End Asm