X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=libsrc%2Fatari%2Fcrt0.s;h=0ea6e390f0f750fbf47032d77fe58aaa55dd1f68;hb=91b9451c60682c0fda984750406d58b1b019f87e;hp=db8a595e30ea3a662092d0d026548face0e9552a;hpb=d3d7499faa74db42edb71c7ee3f3fa16e7b73810;p=cc65

diff --git a/libsrc/atari/crt0.s b/libsrc/atari/crt0.s
index db8a595e3..0ea6e390f 100644
--- a/libsrc/atari/crt0.s
+++ b/libsrc/atari/crt0.s
@@ -8,18 +8,19 @@
 ;       Stefan Haubenthal
 ;
 
-        .export         _exit
         .export         __STARTUP__ : absolute = 1      ; Mark as startup
+        .export         _exit, start
 
         .import         initlib, donelib
         .import         callmain, zerobss
-        .import         __STARTUP_LOAD__, __BSS_LOAD__
         .import         __RESERVED_MEMORY__
         .import         __RAM_START__, __RAM_SIZE__
-.if .defined(__ATARIXL__)
+.ifdef __ATARIXL__
+        .import         __STACKSIZE__
         .import         sram_init
         .import         scrdev
         .import         findfreeiocb
+        .forceimport    sramprep                        ; force inclusion of the "shadow RAM preparation" load chunk
         .include        "save_area.inc"
 .endif
 
@@ -27,47 +28,41 @@
         .include        "atari.inc"
 
 ; ------------------------------------------------------------------------
-; EXE header
-
-.segment        "EXEHDR"
-
-        .word   $FFFF
-
-.if .defined(__ATARIXL__)
-.segment        "MAINHDR"
-.endif
-
-        .word   __STARTUP_LOAD__
-        .word   __BSS_LOAD__ - 1
-
-; ------------------------------------------------------------------------
-; Actual code
 
 .segment        "STARTUP"
 
         rts     ; fix for SpartaDOS / OS/A+
-                ; they first call the entry point from AUTOSTRT and
-                ; then the load addess (this rts here).
+                ; They first call the entry point from AUTOSTRT; and
+                ; then, the load address (this rts here).
                 ; We point AUTOSTRT directly after the rts.
 
 ; Real entry point:
 
-.if .defined(__ATARIXL__)
+start:
+
+.ifdef __ATARIXL__
         jsr     sram_init
 .endif
 
-; Clear the BSS data
+; Clear the BSS data.
 
         jsr     zerobss
 
-; Setup the stack
+; Set up the stack.
 
         tsx
-        stx     spsave
+        stx     SP_save
 
-.if .not .defined(__ATARIXL__)
+.ifdef __ATARIXL__
 
-; Report memory usage
+        lda     #<(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
+        sta     sp
+        lda     #>(__RAM_START__ + __RAM_SIZE__ + __STACKSIZE__)
+        sta     sp+1
+
+.else
+
+; Report the memory usage.
 
         lda     APPMHI
         sta     APPMHI_save             ; remember old APPMHI value
@@ -78,74 +73,67 @@
         lda     MEMTOP
         sbc     #<__RESERVED_MEMORY__
         sta     APPMHI                  ; initialize our APPMHI value
-        sta     sp                      ; setup runtime stack part 1
+        sta     sp                      ; set up runtime stack part 1
         lda     MEMTOP+1
         sbc     #>__RESERVED_MEMORY__
         sta     APPMHI+1
-        sta     sp+1                    ; setup runtime stack part 2
-
-.else
-
-        lda     #<(__RAM_START__ + __RAM_SIZE__ - 1)
-        sta     sp
-        lda     #>(__RAM_START__ + __RAM_SIZE__ - 1)
-        sta     sp+1
+        sta     sp+1                    ; set up runtime stack part 2
 
 .endif
 
-; Call module constructors
+; Call the module constructors.
 
         jsr     initlib
 
-; Set left margin to 0
+; Set the left margin to 0.
 
         lda     LMARGN
-        sta     old_lmargin
+        sta     LMARGN_save
         ldy     #0
         sty     LMARGN
 
-; Set keyb to upper/lowercase mode
+; Set the keyboard to upper-/lower-case mode.
 
         ldx     SHFLOK
-        stx     old_shflok
+        stx     SHFLOK_save
         sty     SHFLOK
 
-; Initialize conio stuff
+; Initialize the conio stuff.
 
-        dey                             ; Set X to $FF
-        sty     CH
+        dey                     ; Set Y to $FF
+        sty     CH              ; remove keypress which might be in the input buffer
 
-; Push arguments and call main
+; Push the command-line arguments; and, call main().
 
         jsr     callmain
 
-; Call module destructors. This is also the _exit entry.
+; Call the module destructors. This is also the exit() entry.
 
 _exit:  jsr     donelib         ; Run module destructors
 
-; Restore system stuff
+; Restore the system stuff.
 
-        ldx     spsave
+        ldx     SP_save
         txs                     ; Restore stack pointer
 
-; Restore left margin
+; Restore the left margin.
 
-        lda     old_lmargin
+        lda     LMARGN_save
         sta     LMARGN
 
-; Restore kb mode
+; Restore the kb mode.
 
-        lda     old_shflok
+        lda     SHFLOK_save
         sta     SHFLOK
 
-; Restore APPMHI
+; Restore APPMHI.
 
         lda     APPMHI_save
         sta     APPMHI
         lda     APPMHI_save+1
         sta     APPMHI+1
 
-.if .defined(__ATARIXL__)
+.ifdef __ATARIXL__
 
 ; Atari XL target stuff...
 
@@ -159,7 +147,9 @@ _exit:  jsr     donelib         ; Run module destructors
         sta     MEMTOP+1
 
 
-; ... issue a GRAPHICS 0 call (copied'n'pasted from TGI drivers)
+; Issue a GRAPHICS 0 call (copied'n'pasted from the TGI drivers), in
+; order to restore screen memory to its default location just
+; before the ROM.
 
         jsr     findfreeiocb
 
@@ -179,19 +169,21 @@ _exit:  jsr     donelib         ; Run module destructors
         lda     #0
         sta     ICBLH,x
         jsr     CIOV_org
-; add error checking here...
+; No error checking here, shouldn't happen(TM); and, no way to
+; recover anyway.
+
         lda     #CLOSE
         sta     ICCOM,x
         jsr     CIOV_org
 
 .endif
 
-; Turn on cursor
+; Turn on the cursor.
 
         ldx     #0
         stx     CRSINH
 
-; Back to DOS
+; Back to DOS.
 
         rts
 
@@ -201,15 +193,9 @@ _exit:  jsr     donelib         ; Run module destructors
 
 .bss
 
-spsave:         .res    1
-old_shflok:     .res    1
-old_lmargin:    .res    1
-.if .not .defined(__ATARIXL__)
+SP_save:        .res    1
+SHFLOK_save:    .res    1
+LMARGN_save:    .res    1
+.ifndef __ATARIXL__
 APPMHI_save:    .res    2
 .endif
-
-
-.segment "AUTOSTRT"
-        .word   RUNAD                   ; defined in atari.inc
-        .word   RUNAD+1
-        .word   __STARTUP_LOAD__ + 1