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cc65/libsrc/cbm/cbm_write.s
cuz 6d498d8187 Use external symbols for the CBM kernal jump table functions. This allows
to emulate these functions on platforms where one or more of these functions
are not available (PET, CBM-II).


git-svn-id: svn://svn.cc65.org/cc65/trunk@1544 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-19 23:02:47 +00:00

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