Handlers which manage the banking in and out of the ROM.

diff --git a/libsrc/atari/shadow_ram_handlers.s b/libsrc/atari/shadow_ram_handlers.s
new file mode 100644 (file)
index 0000000..d3532b2
--- /dev/null
+++ b/libsrc/atari/shadow_ram_handlers.s
@@ -0,0 +1,175 @@
+;
+; Atari XL shadow RAM handlers
+;
+; Christian Groessler, chris@groessler.org, 2013
+;
+
+.if .defined(__ATARIXL__)
+
+        .include        "atari.inc"
+       .include        "save_area.inc"
+       .import         __CHARGEN_START__
+
+       .export         sram_init
+       .export         KEYBDV_wrapper
+
+.macro disable_rom
+       lda     PORTB
+       and     #$fe
+       sta     PORTB
+.endmacro
+.macro enable_rom
+       lda     PORTB
+       ora     #1
+       sta     PORTB
+.endmacro
+
+.segment "INIT"
+
+; Turn off ROMs, install system and interrupt wrappers, set new chargen pointer
+
+sram_init:
+
+; disable all interrupts
+       sei
+       ldx     #0
+       stx     NMIEN           ; disable NMI
+
+       disable_rom
+
+; setup interrupt vectors
+       lda     #<my_IRQ_han
+       sta     $fffe
+       lda     #>my_IRQ_han
+       sta     $ffff
+
+       lda     #<my_RESET_han
+       sta     $fffc
+       lda     #>my_RESET_han
+       sta     $fffd
+
+       lda     #<my_NMI_han
+       sta     $fffa
+       lda     #>my_NMI_han
+       sta     $fffb
+
+; setup pointers to CIOV and SIOV wrappers
+       lda     #$4C            ; JMP opcode
+       sta     CIOV
+       lda     #<my_CIOV
+       sta     CIOV+1
+       lda     #>my_CIOV
+       sta     CIOV+2
+       lda     #$4C            ; JMP opcode
+       sta     SIOV
+       lda     #<my_SIOV
+       sta     SIOV+1
+       lda     #>my_SIOV
+       sta     SIOV+2
+
+; set new chargen
+       lda     #>__CHARGEN_START__
+       sta     CHBAS
+       sta     CHBASE
+
+; enable interrupts
+       lda     #$40
+       sta     NMIEN
+       cli
+
+       rts
+
+
+.segment "LOWCODE"
+
+.macro int_wrap orgvec
+       .local  ret
+       pha
+       enable_rom
+       lda     #>ret
+       pha
+       lda     #<ret
+       pha
+       php
+       jmp     (orgvec)
+ret:   disable_rom
+       pla
+       rti
+.endmacro
+
+my_IRQ_han:
+       int_wrap IRQ_save
+
+my_NMI_han:
+       int_wrap NMI_save
+
+my_RESET_han:
+       int_wrap RESET_save
+
+
+my_CIOV:
+       pha
+       enable_rom
+       pla
+       jsr     CIOV_org
+       php
+       pha
+       disable_rom
+       pla
+       plp
+       rts
+
+my_SIOV:
+       pha
+       enable_rom
+       pla
+       jsr     SIOV_org
+       php
+       pha
+       disable_rom
+       pla
+       plp
+       rts
+
+KEYBDV_wrapper:
+       lda     #>(kret-1)
+       pha
+       lda     #<(kret-1)
+       pha
+       enable_rom
+       lda     KEYBDV+5
+        pha
+        lda     KEYBDV+4
+        pha
+       rts             ; call keyboard handler
+kret:  pha
+       disable_rom
+       pla
+       rts
+
+.if 0
+       .import KEYBDV_wrapper
+        .import cursor,mul40
+
+_cgetc:
+        jsr     setcursor
+.if .not .defined(__ATARIXL__)
+        jsr     @1
+.else
+       jsr     KEYBDV_wrapper
+.endif
+        ldx     #0
+        rts
+
+.if .not .defined(__ATARIXL__)
+@1:     lda     KEYBDV+5
+        pha
+        lda     KEYBDV+4
+        pha
+        lda     #12
+        sta     ICAX1Z          ; fix problems with direct call to KEYBDV
+        rts
+.endif
+.endif
+
+.endif ; .if .defined(__ATARIXL__)