drv/acia: latest bells and whistles

drv/acia.z80

@@ -20,8 +20,8 @@ ACIA_MEM
 	( Read our character from ACIA into our BUFIDX )
     ACIA_CTL INAn,
     0x01 ANDn,   ( is ACIA rcv buf full? )
-    JRZ, L2 FWR ( end, no, wrong interrupt cause. )
-
+    IFNZ,
+        ( correct interrupt cause )
         ( +2 == ACIAW> )
         ACIA_MEM 2+ LDHL(nn),
         ( is it == to ACIAR>? )
@@ -29,8 +29,8 @@ ACIA_MEM
         DE ACIA_MEM LDdd(nn),
         ( carry cleared from ANDn above )
         DE SBCHLss,
-    JRZ, L3 FWR ( end, buffer full )
-
+        IFNZ, ( buffer full? )
+            ( no, continue )
             DE ADDHLss, ( restore ACIAW> )
             ( buffer not full, let's write )
             ACIA_IO INAn,
@@ -43,14 +43,15 @@ ACIA_MEM
             ( +6 == ACIA) )
             DE ACIA_MEM 6 + LDdd(nn),
             DE SUBHLss,
-    JRNZ, L4 FWR ( skip )
-    ( end of buffer reached )
+            IFZ, ( end of buffer reached? )
+                ( yes )
                 ( +4 == ACIA( )
                 ACIA_MEM 4 + LDHL(nn),
                 ( +2 == ACIAW> )
                 ACIA_MEM 2+ LD(nn)HL,
-L4 FSET ( skip )
-L3 FSET L2 FSET ( end )
+            THEN,
+        THEN,
+    THEN,
 
     DE POPqq,
     HL POPqq,