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cc65/libsrc/cbm/cbm_write.s

96 lines
2.1 KiB
ArmAsm

;
; Ullrich von Bassewitz, 15.11.2002
;
; Original C code by Marc 'BlackJack' Rintsch, 25.03.2001
;
; int __fastcall__ cbm_write(unsigned char lfn, void* buffer, unsigned int size)
; {
;
; static unsigned int byteswritten;
;
; /* if we can't change to the outputchannel #lfn then return an error */
; if (_oserror = cbm_k_ckout(lfn)) return -1;
;
; byteswritten = 0;
;
; while (byteswritten<size && !cbm_k_readst()) {
; cbm_k_bsout(((unsigned char*)buffer)[byteswritten++]);
; }
;
; if (cbm_k_readst()) {
; _oserror = 5; /* device not present */
; byteswritten = -1;
; }
;
; cbm_k_clrch();
;
; return byteswritten;
; }
;
.include "cbm.inc"
.export _cbm_write
.import CKOUT, READST, BSOUT, CLRCH
.importzp ptr1, ptr2, ptr3
.import popax, popa
.import __oserror
_cbm_write:
sta ptr3
stx ptr3+1 ; Save size
eor #$FF
sta ptr1
txa
eor #$FF
sta ptr1+1 ; Save -size-1
jsr popax
sta ptr2
stx ptr2+1 ; Save buffer
jsr popa
tax
jsr CKOUT
bcs @E2 ; Branch on error
bcc @L3 ; Branch always
; Loop
@L1: jsr READST
cmp #0 ; Status ok?
bne @E1
ldy #0
lda (ptr2),y ;
inc ptr2
bne @L2
inc ptr2+1 ; A = *buffer++;
@L2: jsr BSOUT ; cbm_k_bsout (A);
@L3: inc ptr1 ; --size;
bne @L1
inc ptr1+1
bne @L1
jsr CLRCH
lda ptr3
ldx ptr3+1 ; return size;
rts
; Error entry, called when READST fails
@E1: lda #5
; Error entry, error code is in A
@E2: sta __oserror
lda #$FF
tax
rts ; return -1