Code & data for "shadow RAM preparation" load chunk in the atarixl target.

Intermediate check-in, unfinished...

diff --git a/libsrc/atari/shadow_ram_prepare.s b/libsrc/atari/shadow_ram_prepare.s
new file mode 100644 (file)
index 0000000..2fc8ffb
--- /dev/null
+++ b/libsrc/atari/shadow_ram_prepare.s
@@ -0,0 +1,185 @@
+;
+; Atari XL shadow RAM preparation routines
+;
+; Tasks:
+; - move screen memory below load address
+; - copy shadow RAM contents to their destination
+;
+; Christian Groessler, chris@groessler.org, 2013
+;
+
+.if .defined(__ATARIXL__)
+
+       .export         sramprep
+        .import         __SRPREP_LOAD__, __SRPREP_SIZE__
+       .import         __SHADOW_RAM_LOAD__, __SHADOW_RAM_SIZE__
+       .import         __CHARGEN_LOAD__, __CHARGEN_SIZE__
+       .import         __SAVEAREA_LOAD__
+
+        .include        "zeropage.inc"
+        .include        "atari.inc"
+       .include        "save_area.inc"
+
+.macro print_string text
+       .local  start, cont
+       jmp     cont
+start: .byte   text, ATEOL
+cont:  ldx     #0              ; channel 0
+       lda     #<start
+       sta     ICBAL,x         ; address
+       lda     #>start
+       sta     ICBAH,x
+       lda     #<(cont - start)
+       sta     ICBLL,x         ; length
+       lda     #>(cont - start)
+       sta     ICBLH,x
+       lda     #PUTCHR
+       sta     ICCOM,x
+       jsr     CIOV
+.endmacro
+
+; ------------------------------------------------------------------------
+; Chunk header
+
+.segment        "SRPREPHDR"
+
+        .word   __SRPREP_LOAD__
+        .word   __SRPREP_LOAD__ + __SRPREP_SIZE__ - 1
+
+; ------------------------------------------------------------------------
+; Actual code
+
+.segment        "SRPREP"
+
+sramprep:
+       print_string "in sramprep"
+
+; save values of modified system variables and ports
+       lda     RAMTOP
+       sta     RAMTOP_save
+       lda     MEMTOP
+       sta     MEMTOP_save
+       lda     MEMTOP+1
+       sta     MEMTOP_save+1
+       lda     APPMHI
+       sta     APPMHI_save
+       lda     APPMHI+1
+       sta     APPMHI_save+1
+       lda     PORTB
+       sta     PORTB_save
+
+; disable BASIC
+
+       lda     PORTB
+       ora     #2
+       sta     PORTB
+
+
+; ... change memory bla
+
+CMPVAL = 64+255+992            ; you may ask, why these values...   @@@ document
+
+sys_ok:        lda     #<__SAVEAREA_LOAD__
+       sec
+       sbc     #<CMPVAL
+       sta     MEMTOP
+       sta     APPMHI
+       lda     #>__SAVEAREA_LOAD__
+       sbc     #>CMPVAL
+       sta     MEMTOP+1
+       sta     APPMHI+1
+
+       lda     #>__SAVEAREA_LOAD__ - 1
+       sta     RAMTOP
+       
+       
+
+; ... issue ar GRAPHICS 0 call (copied'n'pasted from TGI drivers)
+
+
+       ldx     #$50            ; take any IOCB, hopefully free (@@@ fixme)
+
+        ; Reopen it in Graphics 0
+        lda     #OPEN
+        sta     ICCOM,x
+        lda     #OPNIN | OPNOT
+        sta     ICAX1,x
+        lda     #0
+        sta     ICAX2,x
+        lda     #<screen_device
+        sta     ICBAL,x
+        lda     #>screen_device
+        sta     ICBAH,x
+        lda     #<screen_device_length
+        sta     ICBLL,x
+        lda     #>screen_device_length
+        sta     ICBLH,x
+        jsr     CIOV
+       bpl     okoko
+
+       print_string "GR 0 FAILED"
+       jsr     delay
+       jsr     delay
+       jsr     delay
+
+       jmp xxx
+
+okoko:
+
+
+        ; Now close it again; we don't need it anymore :)
+        lda     #CLOSE
+        sta     ICCOM,x
+        jsr     CIOV
+
+       print_string "GR 0 OKOKO"
+       jsr     delay
+
+
+
+
+
+
+xxx:
+
+
+
+
+
+        rts
+
+; short delay
+.proc  delay
+
+       lda     #10
+l:     jsr     delay1
+       clc
+       sbc     #0
+       bne     l
+       rts
+
+delay1:        ldx     #0
+       ldy     #0
+loop:  dey
+       bne     loop
+       dex
+       bne     loop
+       rts
+
+.endproc
+
+screen_device: .byte "S:",0
+screen_device_length = * - screen_device
+
+       .byte   " ** srprep ** end-->"
+
+; ------------------------------------------------------------------------
+; Chunk "trailer" - sets INITAD
+
+.segment        "SRPREPTRL"
+
+        .word   INITAD
+        .word   INITAD+1
+        .word   __SRPREP_LOAD__
+
+.endif ; .if .defined(__ATARIXL__)