cx16: added cx16.push_rambank/rombank and cx16.pop_rambank/rombank for easy temporary bank switching

compiler/res/prog8lib/cx16/syslib.p8

@@ -757,6 +757,42 @@ inline asmsub getrambank() -> ubyte @A {
     }}
 }
 
+inline asmsub push_rombank(ubyte newbank @A) clobbers(Y) {
+    ; push the current rombank on the stack and makes the given rom bank active
+    ; combined with pop_rombank() makes for easy temporary rom bank switch
+    %asm {{
+        ldy  $01
+        phy
+        sta  $01
+    }}
+}
+
+inline asmsub pop_rombank() {
+    ; sets the current rom bank back to what was stored previously on the stack
+    %asm {{
+        pla
+        sta  $01
+    }}
+}
+
+inline asmsub push_rambank(ubyte newbank @A) clobbers(Y) {
+    ; push the current hiram bank on the stack and makes the given hiram bank active
+    ; combined with pop_rombank() makes for easy temporary hiram bank switch
+    %asm {{
+        ldy  $00
+        phy
+        sta  $00
+    }}
+}
+
+inline asmsub pop_rambank() {
+    ; sets the current hiram bank back to what was stored previously on the stack
+    %asm {{
+        pla
+        sta  $00
+    }}
+}
+
 asmsub numbanks() clobbers(X) -> uword @AY {
     ; -- Returns the number of available RAM banks according to the kernal (each bank is 8 Kb).
     ;    Note that the number of such banks can be 256 so a word is returned.

docs/source/technical.rst

@@ -37,7 +37,9 @@ system  get banks (returns byte)                      set banks
 ======= ============================================= ===========
 c64     ``c64.getbanks()``                            ``c64.banks(x)``
 c128    ``c128.getbanks()``                           ``c128.banks(x)``
-cx16    ``cx16.getrombank()`` , ``cx16.getrambank()`` ``cx16.rombank(x)`` , ``cx16.rambank(x)``
+cx16    ``cx16.getrombank()`` , ``cx16.getrambank()`` ``cx16.rombank(x)`` , ``cx16.rambank(x)`` ,
+                                                      ``cx16.push_rombank(x)``, ``cx16.pop_rombank()`` ,
+                                                      ``cx16.push_rambank(x)``, ``cx16.pop_rambank()``
 other   N/A                                           N/A
 ======= ============================================= ===========
 

examples/cx16/banking/program.p8

@@ -14,12 +14,12 @@ main {
         ; load the example libraries in hiram banks 4 and 5
         ; in this example these are constants, but you can also specify
         ; a variable for the bank so you can vary the bank where the routine is loaded.
-        cx16.rambank(4)
+        cx16.push_rambank(4)        ; remember the original ram bank, switch to 4
         void diskio.load("library1.prg", $a000)
         cx16.rambank(5)
         void diskio.load("library2.prg", $a000)
 
-        cx16.rambank(1)
+        cx16.pop_rambank()      ; restore orig rambank.
 
         ; call a routine from the Audio rom bank:
         bool success = audio_init()

examples/test.p8

@@ -1,42 +1,22 @@
-%import test_stack
 %import textio
 %zeropage basicsafe
-%option no_sysinit, romable
 
 main {
 
     sub start()  {
-        str name = "irmen"      ; there a re no memory-mepped strings.
-        ubyte[] array = [11,22,33,44]
-        &ubyte[20] marray = $2000
-        uword @shared pointer = $4000
 
-        sys.memset($2000, 20, 55)
-
-        txt.print(name)
-        txt.spc()
-        txt.print_ub(array[1])
-        txt.spc()
-        txt.print_ub(marray[1])
+        @($a000) = 123
+        txt.print_ub(@($a000))
         txt.nl()
 
-        name[2] = '!'
-        marray[1] = '!'     ; TODO should be allowed because memory mapped to non-rom area
-        array[1], marray[1] = multi()
+        cx16.push_rambank(10)
+        txt.print_ub(@($a000))
+        txt.nl()
+        cx16.pop_rambank()
 
-        cx16.r0L=1
-        pointer[cx16.r0L] = 99
-
-        txt.print(name)
-        txt.spc()
-        txt.print_ub(array[1])
-        txt.spc()
-        txt.print_ub(marray[1])
+        txt.print_ub(@($a000))
         txt.nl()
     }
 
-    sub multi() -> ubyte, ubyte {
-        cx16.r0++
-        return 65,66
-    }
+
 }