mirror of
https://github.com/cc65/cc65.git
synced 2024-12-25 02:29:52 +00:00
51 lines
1.1 KiB
ArmAsm
51 lines
1.1 KiB
ArmAsm
|
;
|
||
|
|
; Karri Kaksonen, 2010
|
||
|
|
;
|
||
|
|
; This function reads count bytes from the place where the address counter is.
|
||
|
|
; Use lseek to place the address counter where you want to read from.
|
||
|
|
;
|
||
|
|
; The file descriptor is ignored in this implementation. The read operation
|
||
|
|
; reads bytes from a raw cart and does not understand the concept of files.
|
||
|
|
; So if you read over the end of file you get data from the next file.
|
||
|
|
;
|
||
|
|
; The count-parameter can be positive (Atari style) or negative (BLL style).
|
||
|
|
; In any case the read routine will work correctly.
|
||
|
|
;
|
||
|
|
; int __fastcall__ read(int fd,void *buf,int count)
|
||
|
|
;
|
||
|
|
.importzp _FileDestPtr
|
||
|
|
.import lynxread0
|
||
|
|
.import pushax,ldaxysp,ldax0sp,incsp6
|
||
|
|
.export _read
|
||
|
|
|
||
|
|
.segment "CODE"
|
||
|
|
|
||
|
|
.proc _read: near
|
||
|
|
|
||
|
|
.segment "CODE"
|
||
|
|
|
||
|
|
jsr pushax
|
||
|
|
ldy #$03
|
||
|
|
jsr ldaxysp
|
||
|
|
sta _FileDestPtr
|
||
|
|
stx _FileDestPtr+1
|
||
|
|
jsr ldax0sp
|
||
|
|
phx ; The BLL kit uses negative counts
|
||
|
|
plx ; while the basic Lynx uses positive
|
||
|
|
bmi @1 ; make all counts negative
|
||
|
|
eor #$FF
|
||
|
|
pha
|
||
|
|
txa
|
||
|
|
eor #$FF
|
||
|
|
bra @2
|
||
|
|
@1: pha
|
||
|
|
txa
|
||
|
|
@2: tay
|
||
|
|
plx
|
||
|
|
jsr lynxread0
|
||
|
|
jsr ldax0sp
|
||
|
|
jmp incsp6
|
||
|
|
|
||
|
|
.endproc
|
||
|
|
|