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cc65/libsrc/common/getcwd.s

67 lines
1.5 KiB
ArmAsm

;
; Ullrich von Bassewitz, 2003-08-12
;
; char* __fastcall__ getcwd (char* buf, size_t size);
;
.export _getcwd
.import popptr1
.import __cwd
.importzp ptr1, ptr2
.include "errno.inc"
;--------------------------------------------------------------------------
.proc _getcwd
; Remember size with each byte incremented because this simplifies the following loop
inx
stx ptr2+1
tax
inx
stx ptr2 ; Save size with each byte incremented separately
jsr popptr1 ; Get buf to ptr1
; Copy __cwd to the given buffer checking the length
; ldy #$00 is guaranteed by popptr1
loop: dec ptr2
bne @L1
dec ptr2+1
beq overflow
; Copy one character, end the loop if the zero terminator is reached. We
; don't support directories longer than 255 characters for now.
@L1: lda __cwd,y
sta (ptr1),y
beq done
iny
bne loop
; For some reason the cwd is longer than 255 characters. This should not
; happen, we handle it as if the passed buffer was too short.
;
; String overflow, return ERANGE
overflow:
lda #<ERANGE
jsr ___seterrno ; Returns 0 in A
tax ; Return zero
rts
; Success, return buf
done: lda ptr1
ldx ptr1+1
rts
.endproc