Merge pull request #50 from groessler/something_to_pull

Add "system check" load chunk to regular (non-XL) Atari target.

cfg/atari-overlay.cfg

@@ -1,16 +1,30 @@
 FEATURES {
-    STARTADDRESS: default = $2E00;
+    STARTADDRESS: default = $2000;
 }
 SYMBOLS {
     __STACKSIZE__:       type = weak, value = $0800; # 2k stack
     __OVERLAYSIZE__:     type = weak, value = $1000; # 4k overlay
+    __STARTADDRESS__:    type = export, value = %S;
     __RESERVED_MEMORY__: type = weak, value = $0000;
+    syschk:              type = import;  # force inclusion of SYSCHK
 }
 MEMORY {
     ZP:            file = "", define = yes, start = $0082, size = $007E;
-    HEADER:  file = %O,               start = $0000,                size = $0006;
+
-    RAM:     file = %O,               start = %S + __OVERLAYSIZE__, size = $BC20 - __STACKSIZE__ - __OVERLAYSIZE__ - %S;
+# file header, just $FFFF
+    HEADER:        file = %O,               start = $0000, size = $0002;
+
+# "system check" load chunk
+    SYSCHKHDR:     file = %O,               start = $0000, size = $0004;
+    SYSCHKCHNK:    file = %O,               start = $2E00, size = $0300;
+    SYSCHKTRL:     file = %O,               start = $0000, size = $0006;
+
+# "main program" load chunk
+    MAINHDR:       file = %O,               start = $0000, size = $0004;
+    RAM:           file = %O, define = yes, start = %S + __OVERLAYSIZE__,
+                                                           size = $BC20 - __OVERLAYSIZE__ - __STACKSIZE__ - __RESERVED_MEMORY__ - %S;
     TRAILER:       file = %O,               start = $0000, size = $0006;
+
     OVL1:          file = "%O.1",           start = %S,    size = __OVERLAYSIZE__;
     OVL2:          file = "%O.2",           start = %S,    size = __OVERLAYSIZE__;
     OVL3:          file = "%O.3",           start = %S,    size = __OVERLAYSIZE__;
@@ -23,6 +37,10 @@ MEMORY {
 }
 SEGMENTS {
     EXEHDR:    load = HEADER,     type = ro;
+    SYSCHKHDR: load = SYSCHKHDR,  type = ro,                optional = yes;
+    SYSCHK:    load = SYSCHKCHNK, type = rw,  define = yes, optional = yes;
+    SYSCHKTRL: load = SYSCHKTRL,  type = ro,                optional = yes;
+    MAINHDR:   load = MAINHDR,    type = ro;
     STARTUP:   load = RAM,        type = ro,  define = yes;
     LOWCODE:   load = RAM,        type = ro,  define = yes, optional = yes;
     INIT:      load = RAM,        type = ro,                optional = yes;

cfg/atari.cfg

@@ -1,18 +1,34 @@
 FEATURES {
-    STARTADDRESS: default = $2E00;
+    STARTADDRESS: default = $2000;
 }
 SYMBOLS {
     __STACKSIZE__:       type = weak, value = $0800; # 2k stack
+    __STARTADDRESS__:    type = export, value = %S;
     __RESERVED_MEMORY__: type = weak, value = $0000;
+    syschk:              type = import;  # force inclusion of SYSCHK
 }
 MEMORY {
     ZP:            file = "", define = yes, start = $0082, size = $007E;
-    HEADER:  file = %O,               start = $0000, size = $0006;
+
-    RAM:     file = %O,               start = %S,    size = $BC20 - __STACKSIZE__ - %S;
+# file header, just $FFFF
+    HEADER:        file = %O,               start = $0000, size = $0002;
+
+# "system check" load chunk
+    SYSCHKHDR:     file = %O,               start = $0000, size = $0004;
+    SYSCHKCHNK:    file = %O,               start = $2E00, size = $0300;
+    SYSCHKTRL:     file = %O,               start = $0000, size = $0006;
+
+# "main program" load chunk
+    MAINHDR:       file = %O,               start = $0000, size = $0004;
+    RAM:           file = %O, define = yes, start = %S,    size = $BC20 - __STACKSIZE__ - __RESERVED_MEMORY__ - %S;
     TRAILER:       file = %O,               start = $0000, size = $0006;
 }
 SEGMENTS {
     EXEHDR:    load = HEADER,     type = ro;
+    SYSCHKHDR: load = SYSCHKHDR,  type = ro,                optional = yes;
+    SYSCHK:    load = SYSCHKCHNK, type = rw,  define = yes, optional = yes;
+    SYSCHKTRL: load = SYSCHKTRL,  type = ro,                optional = yes;
+    MAINHDR:   load = MAINHDR,    type = ro;
     STARTUP:   load = RAM,        type = ro,  define = yes;
     LOWCODE:   load = RAM,        type = ro,  define = yes, optional = yes;
     INIT:      load = RAM,        type = ro,                optional = yes;

libsrc/atari/crt0.s

@@ -34,9 +34,7 @@
 
         .word   $FFFF
 
-.ifdef __ATARIXL__
 .segment        "MAINHDR"
-.endif
 
         .word   __STARTUP_LOAD__
         .word   __BSS_LOAD__ - 1

libsrc/atari/system_check.s

@@ -1,11 +1,14 @@
 ;
-; Atari XL startup system check
+; Atari startup system check
 ;
 ; This routine gets loaded prior to the main part of the executable
 ; and checks if the system is compatible to run the program.
-; It checks whether the system is an XL type one and that enough
+; For the XL target it checks whether the system is an XL type one
-; memory is installed (which isn't the case for a 600XL).
+; and that enough memory is installed (which isn't the case for a 600XL).
-; If the system doesn't qualify, the loading of the main program
+; For the non-XL target it checks whether there is enough memory
+; installed to run the program.
+; For both target it checks that the program won't load below MEMLO.
+; If one of the checks fails the loading of the main program
 ; is aborted by jumping to DOSVEC.
 ;
 ; Christian Groessler, chris@groessler.org, 2013
@@ -13,11 +16,14 @@
 
 ;DEBUG   =       1
 
-.ifdef __ATARIXL__
-
         .export         syschk
         .import         __SYSCHK_LOAD__
-        .import         __STARTADDRESS__       ; needed by xlmemchk.inc
+        .import         __STARTADDRESS__
+
+        ; the following imports are only needed for the 'atari' target version
+        .import         __BSS_SIZE__, __BSS_RUN__
+        .import         __STACKSIZE__
+        .import         __RESERVED_MEMORY__
 
         .include        "zeropage.inc"
         .include        "atari.inc"
@@ -59,25 +65,26 @@ cont:   ldx     #0              ; channel 0
 
 
 ; ------------------------------------------------------------------------
-; Chunk header
+; code
-
-.segment        "SYSCHKHDR"
-
-        .word   __SYSCHK_LOAD__
-        .word   end - 1
-
-; ------------------------------------------------------------------------
-; Actual code
 
 .segment        "SYSCHK"
 
+.ifdef __ATARIXL__
+
+lmemerrxl_txt:
+        .byte   "Not enough memory to move screen", ATEOL
+        .byte   "memory to low memory. Consider using", ATEOL
+        .byte   "a higher load address.", ATEOL
+lmemerrxl_txt_len = * - lmemerrxl_txt
+
 ; no XL machine
 no_xl:  print_string "This program needs an XL machine."
         jmp     fail
 
-; entry point
+
-syschk:
+; ***** entry point (atarixl) *****
-        lda     $fcd8           ; from ostype.s
+
+syschk: lda     $fcd8           ; from ostype.s
         cmp     #$a2
         beq     no_xl
 
@@ -86,11 +93,7 @@ syschk:
         cmp     #$80
         bcs     sys_ok
 
-; not enough memory
+        jmp     mem_err
-        print_string "Not enough memory."
-fail:   jsr     delay
-        jmp     (DOSVEC)
-
 
 sys_ok:
         .include "xlmemchk.inc"         ; calculate lowest address we will use when we move the screen buffer down
@@ -102,11 +105,63 @@ sys_ok:
         sbc     lowadr+1
         bcc     memlo_ok
 
+; load address was too low
+        print_string2 lmemerrxl_txt, lmemerrxl_txt_len
+        jsr     delay           ; long text takes longer to read, give user additional time
+        jmp     fail
+
+.else   ; above 'atarixl', below 'atari'
+
+.define CIOV_org CIOV           ; the print_string macros use CIOV_org, map this to CIOV
+
+lmemerr_txt:
+        .byte   "Program would load below MEMLO.", ATEOL
+        .byte   "Consider using a higher load address.", ATEOL
+lmemerr_txt_len = * - lmemerr_txt
+
+
+; ***** entry point (atari) *****
+
+syschk:
+        sec
+        lda     MEMTOP
+        sbc     #<__RESERVED_MEMORY__
+        sta     tmp
+        lda     MEMTOP+1
+        sbc     #>__RESERVED_MEMORY__
+        sta     tmp+1
+        lda     tmp
+        sec
+        sbc     #<__STACKSIZE__
+        sta     tmp
+        lda     tmp+1
+        sbc     #>__STACKSIZE__
+        sta     tmp+1
+
+;tmp contains address which must be above .bss's end
+
+        sec
+        lda     tmp
+        sbc     #<(__BSS_RUN__ + __BSS_SIZE__)
+        lda     tmp+1
+        sbc     #>(__BSS_RUN__ + __BSS_SIZE__)
+
+        bcc     mem_err         ; program doesn't fit into memory
+
+        sec
+        lda     MEMLO
+        sbc     #<__STARTADDRESS__
+        lda     MEMLO+1
+        sbc     #>__STARTADDRESS__
+        bcc     memlo_ok
+
 ; load address was too low
         print_string2 lmemerr_txt, lmemerr_txt_len
         jsr     delay           ; long text takes longer to read, give user additional time
         jmp     fail
 
+.endif
+
 ; all is well(tm), launch the application
 memlo_ok:
 .ifdef DEBUG
@@ -115,36 +170,45 @@ memlo_ok:
 .endif
         rts
 
-
+; not enough memory
-lmemerr_txt:
+mem_err:print_string "Not enough memory."
-        .byte   "Not enough memory to move screen", ATEOL
+fail:   jsr     delay
-        .byte   "memory to low memory. Consider using", ATEOL
+        jmp     (DOSVEC)
-        .byte   "a higher load address.", ATEOL
-lmemerr_txt_len = * - lmemerr_txt
-
 
 ; short delay
 .proc   delay
 
         lda     #10
-l:      jsr     delay1
+@loop:  jsr     delay1
         clc
         sbc     #0
-        bne     l
+        bne     @loop
         rts
 
 delay1: ldx     #0
         ldy     #0
-loop:   dey
+@loop:  dey
-        bne     loop
+        bne     @loop
         dex
-        bne     loop
+        bne     @loop
         rts
 
 .endproc
 
 end:
 
+.ifndef __ATARIXL__
+tmp:		; outside of the load chunk, some kind of poor man's .bss
+.endif
+
+; ------------------------------------------------------------------------
+; Chunk header
+
+.segment        "SYSCHKHDR"
+
+        .word   __SYSCHK_LOAD__
+        .word   end - 1
+
 ; ------------------------------------------------------------------------
 ; Chunk "trailer" - sets INITAD
 
@@ -153,5 +217,3 @@ end:
         .word   INITAD
         .word   INITAD+1
         .word   syschk
-
-.endif  ; .ifdef __ATARIXL__