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

Makefile

@@ -8,7 +8,7 @@ LIBS=clib-6502.a
 
 
 # Common source files
-ASM_SRCS = tk2k_startup.s
+ASM_SRCS = tk2k_startup.s preserve_zero_pages.s
 C_SRCS = main.c monitor_subroutines.c utility.c \
 		game_graphics.c game_logic.c input.c \
 		line_data.c tiles.c graph_misc_data.c \
@@ -26,8 +26,7 @@ all: $(PRG).wav
 	cc6502 --core=6502 -O2 --list-file=$(@:%.o=obj/%.lst) --char-is-unsigned --pedantic-errors -o obj/$@ $<
 
 $(PRG).hex: $(OBJS)
-#	(cd obj ; ln6502 -g ../linker-files/linker.scm  $^ -o ../out/$@ $(LIBS) -l --cross-reference --cstartup=tk2k --no-automatic-placement-rules --output-format intel-hex --hosted)
-	(cd obj ; ln6502 -g ../linker-files/linker.scm  $^ -o ../out/$@ $(LIBS) -l --cross-reference --cstartup=tk2k --no-automatic-placement-rules --output-format intel-hex)
+	(cd obj ; ln6502 -g ../linker-files/linker.scm  $^ -o ../out/$@ $(LIBS) -l --cross-reference --cstartup=tk2k --no-automatic-placement-rules --output-format intel-hex --rom-code)
 
 $(PRG).bin: $(PRG).hex
 	(cd out ; objcopy -I ihex -O binary $(PRG).hex $(PRG).bin)

linker-files/linker.scm

@@ -4,11 +4,10 @@
 	(memory firstPage (address (#x100 . #x1ff)) (section stack))
     (memory reserved (address (#x200 . #x7ff)) (type ram))
 	(memory program (address (#x801 . #x1fff)) (type ram)
-;;;		(section (programStart #x801) (startup #x80e) code switch idata cdata data_init_table))
-		(section (programStart #x801) (startup #x80e) code))
+		(section (programStart #x801) startup code))
 	(memory displayPage1 (address (#x2000 . #x3fff)) (type ram) (section loadscreen))
 	(memory upperData (address (#x4000 . #x85ff)) (type ram) (section switch idata cdata data_init_table)) ;;; usermem goes from 0x4000 to 0x9FFFF (included), we are splitting it
-	(memory upperMem (address (#x8600 . #x95ff)) (type ram) (section cstack zdata data heap))
+	(memory upperMem (address (#x8600 . #x95ff)) (type ram) (section cstack zdata data heap zpsave))
 	(memory dosMem (address (#x9600 . #x9fff)) (type ram))
 	(memory displayPage2 (address (#xa000 . #xbfff)) (type ram))
 	(memory io (address (#xc000 . #xc0ff)) (type ram))

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.