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cc65/libsrc/sym1/write.s
2021-06-12 06:17:03 -05:00

53 lines
1.2 KiB
ArmAsm

;
; Wayne Parham (wayne@parhamdata.com)
;
; int write (int fd, const void* buf, int count);
;
.include "sym1.inc"
.import popax, popptr1
.importzp ptr1, ptr2, ptr3
.export _write
.proc _write
sta ptr3
stx ptr3+1 ; Count in ptr3
inx
stx ptr2+1 ; Increment and store in ptr2
tax
inx
stx ptr2
jsr popptr1 ; Buffer address in ptr1
jsr popax
begin: dec ptr2
bne outch
dec ptr2+1
beq done
outch: ldy #0
lda (ptr1),y
jsr OUTCHR ; Send character using Monitor call
cmp #$07 ; Check for '\a'
bne chklf ; ...if BEL character
jsr BEEP ; Make beep sound
chklf: cmp #$0A ; Check for 'n'
bne next ; ...if LF character
lda #$0D ; Add a carriage return
jsr OUTCHR
next: inc ptr1
bne begin
inc ptr1+1
jmp begin
done: lda ptr3
ldx ptr3+1
rts ; Return count
.endproc