#295 extended memory access with FC@ and FC!

TG9541 · Jul 26, 2020 · 911d4ae · 911d4ae
1 parent a9e1b61
commit 911d4ae
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diff --git a/lib/FC! b/lib/FC!
@@ -0,0 +1,14 @@
+\ STM8eForth : FC!                                                 TG9541-200726
+\ ------------------------------------------------------------------------------
+
+\ store char c to far address ah:al
+: FC! ( c al ah -- ) [
+  \ Note: creates/executes LDF A,ah:al + RET code on the Data Stack
+  $A6BD ,          \        LD      A,#0xBD         ; Opcode LDF ExtAddr,A
+  $F7  C,          \        LD      (X),A           ; MSB of ah (instead of "0")
+  $A681 ,          \        LD      A,#0x81         ; Opcode RET
+  $E704 ,          \        LD      (4,X),A         ; MSB of C (instead of "0")
+  $E605 ,          \        LD      A,(5,X)         ; load C
+  $FD  C,          \        CALL    (X)             ; execute LDF
+  $1C  C, $0006 ,  \        ADDW    X,#6            ; DROP all
+] ;
diff --git a/lib/FC@ b/lib/FC@
@@ -0,0 +1,14 @@
+\ STM8eForth : FC@                                                 TG9541-200726
+\ ------------------------------------------------------------------------------
+
+\ read char c at far address ah:al
+: FC@ ( al ah -- c )
+  \ Note: creates/executes LDF ah:al,A + RET code on the Data Stack
+  $8100 ROT ROT [  \ get a RET ready
+  $A6BC ,          \        LD      A,#0xBC         ; Opcode LDF A,ExtAddr
+  $F7  C,          \        LD      (X),A           ; MSB of ah (instead of "0")
+  $FD  C,          \        CALL    (X)             ; execute LDF
+  $6F04 ,          \        CLR     (4,X)           ; bring c onto stack
+  $E705 ,          \        LD      (5,X),A
+  ] 2DROP          \ remove LDF ah:al
+;