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cc65/libsrc/lynx/lynx-cart.s

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; ***
; CC65 Lynx Library
;
; Originally by Bastian Schick
; http://www.geocities.com/SiliconValley/Byte/4242/lynx/
;
; Ported to cc65 (http://www.cc65.org) by
; Shawn Jefferson, June 2004
;
; This version by Karri Kaksonen, December 2010
;
; Helper stuff for the cartridge file functions. This version can deal
; with 1024 bytes/block carts that are using CART0 as a read strobe.
; Also the default crt0.s supports this most common Lynx cart format.
.include "lynx.inc"
.include "extzp.inc"
.export lynxskip0, lynxread0
.export lynxblock
.import __BLOCKSIZE__
.code
;**********************************
; Skip bytes on bank 0
; X:Y count (EOR $FFFF)
;**********************************
lynxskip0:
inx
bne @0
iny
beq exit
@0: jsr readbyte0
bra lynxskip0
;**********************************
; Read bytes from bank 0
; X:Y count (EOR $ffff)
;**********************************
lynxread0:
inx
bne @1
iny
beq exit
@1: jsr readbyte0
sta (_FileDestPtr)
inc _FileDestPtr
bne lynxread0
inc _FileDestPtr+1
bra lynxread0
;**********************************
; Read one byte from cartridge
;**********************************
readbyte0:
lda RCART0
inc _FileBlockByte
bne exit
inc _FileBlockByte+1
bne exit
;**********************************
; Select a block
;**********************************
lynxblock:
pha
phx
phy
lda __iodat
and #$fc
tay
ora #2
tax
lda _FileCurrBlock
inc _FileCurrBlock
sec
bra @2
@0: bcc @1
stx IODAT
clc
@1: inx
stx SYSCTL1
dex
@2: stx SYSCTL1
rol
sty IODAT
bne @0
lda __iodat
sta IODAT
stz _FileBlockByte
lda #<($100-(>__BLOCKSIZE__))
sta _FileBlockByte+1
ply
plx
pla
exit: rts