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Viewing changes to tools/sfio/sfungetc.c

  • Committer: Bazaar Package Importer
  • Author(s): Stephen M Moraco
  • Date: 2002-02-05 18:52:12 UTC
  • Revision ID: james.westby@ubuntu.com-20020205185212-8i04c70te00rc40y
Tags: upstream-1.7.16
Import upstream version 1.7.16

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tools/sfio/sfungetc.c
 
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#include        "sfhdr.h"
 
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/*      Push back one byte to a given SF_READ stream
 
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**
 
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**      Written by Kiem-Phong Vo.
 
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*/
 
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#if __STD_C
 
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static int _uexcept(reg Sfio_t* f, reg int type, Void_t* val, reg Sfdisc_t* disc)
 
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#else
 
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static int _uexcept(f,type,val,disc)
 
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reg Sfio_t      *f;
 
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reg int         type;
 
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Void_t*         val;
 
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reg Sfdisc_t    *disc;
 
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#endif
 
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{       
 
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        NOTUSED(val);
 
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        /* hmm! This should never happen */
 
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        if(disc != _Sfudisc)
 
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                return -1;
 
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        /* close the unget stream */
 
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        if(type != SF_CLOSING)
 
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                (void)sfclose((*_Sfstack)(f,NIL(Sfio_t*)));
 
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        return 1;
 
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}
 
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#if __STD_C
 
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int sfungetc(reg Sfio_t* f, reg int c)
 
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#else
 
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int sfungetc(f,c)
 
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reg Sfio_t*     f;      /* push back one byte to this stream */
 
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reg int         c;      /* the value to be pushed back */
 
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#endif
 
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{
 
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        reg Sfio_t*     uf;
 
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        SFMTXSTART(f, -1)
 
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        if(c < 0 || (f->mode != SF_READ && _sfmode(f,SF_READ,0) < 0))
 
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                SFMTXRETURN(f, -1);
 
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        SFLOCK(f,0);
 
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        /* fast handling of the typical unget */
 
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        if(f->next > f->data && f->next[-1] == (uchar)c)
 
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        {       f->next -= 1;
 
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                goto done;
 
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        }
 
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        /* make a string stream for unget characters */
 
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        if(f->disc != _Sfudisc)
 
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        {       if(!(uf = sfnew(NIL(Sfio_t*),NIL(char*),(size_t)SF_UNBOUND,
 
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                                -1,SF_STRING|SF_READ)))
 
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                {       c = -1;
 
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                        goto done;
 
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                }
 
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                _Sfudisc->exceptf = _uexcept;
 
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                sfdisc(uf,_Sfudisc);
 
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                SFOPEN(f,0); (void)sfstack(f,uf); SFLOCK(f,0);
 
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        }
 
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        /* space for data */
 
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        if(f->next == f->data)
 
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        {       reg uchar*      data;
 
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                if(f->size < 0)
 
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                        f->size = 0;
 
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                if(!(data = (uchar*)malloc(f->size+16)))
 
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                {       c = -1;
 
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                        goto done;
 
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                }
 
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                f->flags |= SF_MALLOC;
 
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                if(f->data)
 
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                        memcpy((char*)(data+16),(char*)f->data,f->size);
 
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                f->size += 16;
 
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                f->data  = data;
 
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                f->next  = data+16;
 
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                f->endb  = data+f->size;
 
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        }
 
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        *--f->next = (uchar)c;
 
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done:
 
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        SFOPEN(f,0);
 
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        SFMTXRETURN(f, c);
 
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}