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36 lines
1.3 KiB
C
36 lines
1.3 KiB
C
/**************************************************************************
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*
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* u n g e t c F u n c t i o n
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* -----------------------------
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* Copyright 1982 by Digital Research Inc. All rights reserved.
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*
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* "ungetc" puts a char back into its (read only) stream. It's
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* guaranteed to work for at least one char, provided the
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* stream is buffered and something has been read.
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*
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* Calling sequence:
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* ret = ungetc(c,stream)
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* Where:
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* ret = c if it worked, FAILURE o.w.
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* c = char to push back
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* stream -> (FILE *) place to push back to
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*
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*****************************************************************************/
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#include <stdio.h>
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WORD ungetc(c,sp) /****************************/
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REG WORD c; /* char to unget */
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REG FILE *sp; /* stream to unget to */
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{ /****************************/
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if( c == EOF ) /* no allowed if EOF */
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return(FAILURE); /* */
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if( sp->_flag & _IOREAD /* if file is read able */
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&& sp->_base != NULL /* and something's read */
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&& sp->_ptr > sp->_base ) /* and buffer not empty */
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{ /* then... */
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*--sp->_ptr = c; /* back up buffer & store */
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sp->_cnt++; /* there's one more byte */
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return(c); /* it worked! */
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} /****************************/
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return(FAILURE); /* it didn't work... */
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} /****************************/
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