C128: adjust MEMTOP value to $C000 during runtime (41 Kb of available space because Basic ROM is banked out)

compiler/res/prog8lib/c128/syslib.p8

@@ -1302,6 +1302,11 @@ asmsub  init_system()  {
         lda  #0
         sta  c64.BGCOL0
         jsr  disable_runstop_and_charsetswitch
+        ; basic is not banked in, adjust MEMTOP
+        ldx  #<$c000
+        ldy  #>$c000
+        clc
+        jsr  cbm.MEMTOP
         cli
         rts
     }}
@@ -1323,6 +1328,10 @@ asmsub  cleanup_at_exit() {
         sta  $ff00          ; default bank 15
         jsr  cbm.CLRCHN		; reset i/o channels
         jsr  enable_runstop_and_charsetswitch
+        ldx  #<$ff00
+        ldy  #>$ff00
+        clc
+        jsr  cbm.MEMTOP     ; adjust MEMTOP to original value again
         lda  _exitcarry
         lsr  a
         lda  _exitcode

docs/source/introduction.rst

@@ -101,6 +101,7 @@ Language Features
 - Supports the sixteen 'virtual' 16-bit registers R0 to R15 as defined on the Commander X16. You can look at them as general purpose global variables. These are also available on the other compilation targets!
 - On the Commander X16: Support for low level system features such as Vera Fx, which includes 16x16 bits multiplication in hardware and fast memory copy and fill.
 - 50 Kb of available program RAM size on the C64 by default; because Basic ROM is banked out altogether
+- 41 Kb of available program RAM size on the C128 by default; because Basic ROM is banked out altogether
 - Many library routines are available across compiler targets. This means that as long as you only use standard Kernal
   and core prog8 library routines, it is sometimes possible to compile the *exact same program* for different machines by just changing the compilation target flag.
 

examples/test.p8

@@ -1,24 +1,52 @@
 %import textio
 %zeropage basicsafe
+;;%option no_sysinit
 
 main {
     sub start() {
-        long @shared lv1 = -123456
-
-        txt.print_l(abs(lv1))
-        txt.spc()
-
-        lv1 = -99999
-        lv1 = abs(lv1)
-        txt.print_l(abs(lv1))
+        txt.print("memtop=")
+        cx16.r0 = cbm.MEMTOP(0, true)
+        txt.print_uwhex(cx16.r0, true)
         txt.nl()
 
-        cx16.r4 = $1122
-        cx16.r5 = $abcd
-        txt.print_ulhex(mklong(cx16.r5H,cx16.r5L,cx16.r4H,cx16.r4L), true)
+        txt.print("bfff: ")
+        @($bfff) = 123
+        cx16.r9++
+        txt.print_ub(@($bfff))
         txt.spc()
-        txt.print_ulhex(mklong2(cx16.r5,cx16.r4), true)
+        @($bfff) = 0
+        cx16.r9++
+        txt.print_ub(@($bfff))
         txt.nl()
 
+        txt.print("c000: ")
+        @($c000) = 123
+        cx16.r9++
+        txt.print_ub(@($c000))
+        txt.spc()
+        @($c000) = 0
+        cx16.r9++
+        txt.print_ub(@($c000))
+        txt.nl()
+
+        txt.print("d000: ")
+        @($d000) = 123
+        cx16.r9++
+        txt.print_ub(@($d000))
+        txt.spc()
+        @($d000) = 0
+        cx16.r9++
+        txt.print_ub(@($d000))
+        txt.nl()
+
+        txt.print("e000: ")
+        @($e000) = 123
+        cx16.r9++
+        txt.print_ub(@($e000))
+        txt.spc()
+        @($e000) = 0
+        cx16.r9++
+        txt.print_ub(@($e000))
+        txt.nl()
     }
 }