Restore ZP saving, add initialization of ZP, remove BASIC stub

src/main.c

@@ -11,6 +11,7 @@
 #include "game_graphics.h"
 #include "monitor_subroutines.h"
 
+#pragma require __preserve_zp
 // Make sure the loading screen is included
 #pragma require __loading_screen
 

src/preserve_zero_pages.s

@@ -0,0 +1,12 @@
+              .rtmodel version, "1"
+              .rtmodel core, "*"
+
+              ;; External declarations
+              .section registers    ; pseudo registers in zero page
+
+              .section zpsave, noinit
+              .pubweak __preserve_zp
+__preserve_zp:                      ; This symbol meant to be required
+	      .space  256	   
+	      .require __preserve_zp_needed
+              .require __restore_zp_needed

src/tk2k_startup.s

@@ -7,6 +7,7 @@
               .section heap
               .section data_init_table
 			  .section registers    ; pseudo registers in zero page
+			  .section zpsave	    ; this is where pseudo registers are saved
 
               .extern main, exit, __low_level_init
               .extern _Zp, _Vsp, _Vfp
@@ -19,14 +20,23 @@ call:         .macro  dest
 
               .section programStart, root
 __program_root_section:
-			  .word nextLine
-			  .byte 0x0a, 0x00 ; 10
-			  .byte 0x8c, 0x32, 0x30, 0x36, 0x32, 0x00 ; CALL 2062
-nextLine:	  .byte 0x00, 0x00 ; end of program
-
+			  jmp __program_start
               .section startup, root, noreorder
 __program_start:
               .section startup, noreorder
+              .pubweak __preserve_zp_needed
+__preserve_zp_needed:
+              ldx     #.sectionSize registers - 1
+-             lda     zp:.sectionStart registers,x
+              sta     .sectionStart zpsave,x
+              dex
+              bpl     -
+
+              .section startup, root, noreorder
+              lda     #.byte0(.sectionEnd cstack)
+              sta     zp:_Vsp
+              lda     #.byte1(.sectionEnd cstack)
+              sta     zp:_Vsp+1
               jsr     __low_level_init
 
 ;;; Initialize data sections if needed.