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  • 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/sfstack.c
 
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#include        "sfhdr.h"
 
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/*      Push/pop streams
 
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**
 
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**      Written by Kiem-Phong Vo.
 
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*/
 
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#define STKMTXLOCK(f1,f2) \
 
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        { if(f1) SFMTXLOCK(f1); \
 
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          if(f2) SFMTXLOCK(f2); \
 
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        }
 
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#define STKMTXRETURN(f1,f2,rv) \
 
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        { if(f1) SFMTXUNLOCK(f1); \
 
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          if(f2) SFMTXUNLOCK(f2); \
 
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          return(rv); \
 
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        }
 
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#if __STD_C
 
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Sfio_t* sfstack(Sfio_t* f1, Sfio_t* f2)
 
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#else
 
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Sfio_t* sfstack(f1,f2)
 
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Sfio_t* f1;     /* base of stack        */
 
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Sfio_t* f2;     /* top of stack */
 
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#endif
 
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{
 
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        reg int         n;
 
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        reg Sfio_t*     rf;
 
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        reg Sfrsrv_t*   rsrv;
 
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        reg Vtmutex_t*  mtx;
 
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        STKMTXLOCK(f1,f2);
 
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        if(f1 && (f1->mode&SF_RDWR) != f1->mode && _sfmode(f1,0,0) < 0)
 
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                STKMTXRETURN(f1,f2, NIL(Sfio_t*));
 
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        if(f2 && (f2->mode&SF_RDWR) != f2->mode && _sfmode(f2,0,0) < 0)
 
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                STKMTXRETURN(f1,f2, NIL(Sfio_t*));
 
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        if(!f1)
 
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                STKMTXRETURN(f1,f2, f2);
 
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        /* give access to other internal functions */
 
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        _Sfstack = sfstack;
 
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        if(f2 == SF_POPSTACK)
 
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        {       if(!(f2 = f1->push))
 
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                        STKMTXRETURN(f1,f2, NIL(Sfio_t*));
 
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                f2->mode &= ~SF_PUSH;
 
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        }
 
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        else
 
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        {       if(f2->push)
 
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                        STKMTXRETURN(f1,f2, NIL(Sfio_t*));
 
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                if(f1->pool && f1->pool != &_Sfpool && f1->pool != f2->pool &&
 
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                   f1 == f1->pool->sf[0])
 
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                {       /* get something else to pool front since f1 will be locked */
 
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                        for(n = 1; n < f1->pool->n_sf; ++n)
 
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                        {       if(SFFROZEN(f1->pool->sf[n]) )
 
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                                        continue;
 
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                                (*_Sfpmove)(f1->pool->sf[n],0);
 
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                                break;
 
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                        }
 
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                }
 
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        }
 
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        if(f2->pool && f2->pool != &_Sfpool && f2 != f2->pool->sf[0])
 
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                (*_Sfpmove)(f2,0);
 
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        /* swap streams */
 
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        sfswap(f1,f2);
 
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        /* but the reserved buffer and mutex must remain the same */
 
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        rsrv = f1->rsrv; f1->rsrv = f2->rsrv; f2->rsrv = rsrv;
 
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        mtx = f1->mutex; f1->mutex = f2->mutex; f2->mutex = mtx;
 
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        SFLOCK(f1,0);
 
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        SFLOCK(f2,0);
 
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        if(f2->push != f2)
 
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        {       /* freeze the pushed stream */
 
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                f2->mode |= SF_PUSH;
 
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                f1->push = f2;
 
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                rf = f1;
 
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        }
 
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        else
 
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        {       /* unfreeze the just exposed stream */
 
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                f1->mode &= ~SF_PUSH;
 
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                f2->push = NIL(Sfio_t*);
 
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                rf = f2;
 
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        }
 
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        SFOPEN(f1,0);
 
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        SFOPEN(f2,0);
 
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        STKMTXRETURN(f1,f2, rf);
 
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}