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72 lines
1.3 KiB
ArmAsm
72 lines
1.3 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 2004-05-12
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;
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; int __fastcall__ ungetc (int c, FILE* f);
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; /* Push back a character into a file stream. */
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;
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.export _ungetc
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.import popax
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.import ptr1: zp, tmp1: zp
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.include "_file.inc"
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.include "errno.inc"
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; ------------------------------------------------------------------------
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; Code
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.proc _ungetc
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; Save the file pointer to ptr1
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sta ptr1
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stx ptr1+1
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; Get c from stack and save the lower byte in tmp1
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jsr popax
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sta tmp1
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; c must be in char range
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txa
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bne error
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; Check if the file is open
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ldy #_FILE::f_flags
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lda (ptr1),y
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and #_FOPEN ; Is the file open?
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beq error ; Branch if no
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; Set the pushback flag and reset the end-of-file indicator
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lda (ptr1),y
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ora #_FPUSHBACK
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and #<~_FEOF
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sta (ptr1),y
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; Store the character into the pushback buffer
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ldy #_FILE::f_pushback
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lda tmp1
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sta (ptr1),y
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; Done, return c
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ldx #0
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rts
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; File is not open or the character is invalid
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error: lda #EINVAL
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jsr __seterrno
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lda #$FF ; Return -1
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tax
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rts
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.endproc
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