zx128: banking helpers

Just filling them out for the moment. They try and use logical not real
bank numbers so won't actually work yet

diff --git a/Kernel/platform-zx128/zx128.s b/Kernel/platform-zx128/zx128.s
index c817d8f..9ff6d29 100644 (file)
--- a/Kernel/platform-zx128/zx128.s
+++ b/Kernel/platform-zx128/zx128.s
@@ -179,16 +179,83 @@ place_for_b:                ; And BC - here
 place_for_c:
         .db 0
 
+       .area _COMMONMEM
 ;
 ;      Banking helpers
 ;
+;      FIXME: use real bank asssignments (0 is not 0 etc)
+;
 __bank_0_1:
+       ld a, #1
+bankina0:
+       call switch_bank   ; Move to new bank
+       pop hl             ; Return address (points to true function address)
+       ld e, (hl)         ; DE = function to call
+       inc hl
+       ld d, (hl)
+       inc hl
+       push hl            ; Restore corrected return pointer
+       ex de, hl
+       call callhl        ; call the function
+       xor a              ; return to bank 0
+       jp switch_bank
+callhl:        jp (hl)
 __bank_0_2:
+       ld a, #2
+       jr bankina0
 __bank_0_3:
+       ld a, #3
+       jr bankina0
+
 __bank_1_2:
+       ld a, #2
+bankina1:
+       call switch_bank   ; Move to new bank
+       pop hl             ; Return address (points to true function address)
+       ld e, (hl)         ; DE = function to call
+       inc hl
+       ld d, (hl)
+       inc hl
+       push hl            ; Restore corrected return pointer
+       ex de, hl
+       call callhl        ; call the function
+       ld a, #1           ; return to bank 0
+       jp switch_bank
 __bank_1_3:
+       ld a, #3
+       jr bankina1
 __bank_2_1:
+       ld a, #1
+bankina2:
+       call switch_bank   ; Move to new bank
+       pop hl             ; Return address (points to true function address)
+       ld e, (hl)         ; DE = function to call
+       inc hl
+       ld d, (hl)
+       inc hl
+       push hl            ; Restore corrected return pointer
+       ex de, hl
+       call callhl        ; call the function
+       ld a, #2           ; return to bank 0
+       jp switch_bank
 __bank_2_3:
+       ld a, #3
+       jr bankina2
 __bank_3_1:
+       ld a, #1
+bankina3:
+       call switch_bank   ; Move to new bank
+       pop hl             ; Return address (points to true function address)
+       ld e, (hl)         ; DE = function to call
+       inc hl
+       ld d, (hl)
+       inc hl
+       push hl            ; Restore corrected return pointer
+       ex de, hl
+       call callhl        ; call the function
+       ld a, #2           ; return to bank 0
+       jp switch_bank
+
 __bank_3_2:
-       ret
+       ld a, #2
+       jr bankina3