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cc65/libsrc/telestrat/read.s
2020-10-23 23:47:30 +02:00

52 lines
1.1 KiB
ArmAsm

;
; jede jede@oric.org 2017-01-22
;
.export _read
.import popax
.include "zeropage.inc"
.include "telestrat.inc"
.include "fcntl.inc"
;int read (int fd, void* buf, unsigned count);
.proc _read
sta ptr1 ; count
stx ptr1+1 ; count
jsr popax ; get buf
sta PTR_READ_DEST
stx PTR_READ_DEST+1
sta ptr2 ; in order to calculate nb of bytes read
stx ptr2+1 ;
jsr popax ; fp pointer don't care in this version
cpx #$00
bne @is_not_stdin
cmp #STDIN_FILENO
bne @is_not_stdin
; stdin
@L1:
BRK_TELEMON XRD0 ; waits until key is pressed
bcs @L1
rts
@is_not_stdin:
lda ptr1 ;
ldy ptr1+1 ;
BRK_TELEMON XFREAD ; calls telemon30 routine
; compute nb of bytes read
lda PTR_READ_DEST+1
sec
sbc ptr2+1
tax
lda PTR_READ_DEST
sec
sbc ptr2
; Here A and X contains number of bytes read
rts
.endproc