42 lines
1.5 KiB
C
42 lines
1.5 KiB
C
/* VALLOC - Aligned memory allocator
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* Emulation of the 4.2BSD library routine of the same name.
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* Copyright 1985 by Ken Harrenstien, SRI International
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* This software is quasi-public; it may be used freely with
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* like software, but may NOT be sold or made part of licensed
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* products without permission of the author. In all cases
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* the source code and any modifications thereto must remain
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* available to any user.
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*
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* This is part of the SB library package.
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* Any software using the SB library must likewise be made
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* quasi-public, with freely available sources.
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*/
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#include "sb.h"
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char *
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valloc(size)
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unsigned size;
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{ register int pagmsk;
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register SBMO i;
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register struct smblk *sm, *smr;
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struct smblk *sbm_mget(), *sbm_split();
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pagmsk = getpagesize() - 1; /* Get page size in bytes, less 1 */
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if(!(sm = sbm_mget(size+pagmsk, size+pagmsk))) /* Get area big enuf */
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return(0);
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/* Now find # bytes prior to 1st page boundary.
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* This expression gives 0 if already at boundary, else #-1.
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*/
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i = pagmsk - ((int)(sm->smaddr) & pagmsk);
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if(i) /* If need to split off preceding stuff, */
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{ smr = sbm_split(sm, i+1); /* do so (note i adjusted) */
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sbm_mfree(sm); /* Release preceding mem */
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if(!(sm = smr)) return(0); /* If couldn't split, fail */
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}
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if(i = (sm->smlen - size)) /* See if any trailing stuff */
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{ smr = sbm_split(sm, size); /* Yeah, split it off too */
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if(smr) sbm_mfree(smr); /* If couldn't split, excess OK. */
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}
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return((char *)(sm->smaddr));
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}
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