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80 lines
2.2 KiB
C
80 lines
2.2 KiB
C
/*
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http://code.google.com/p/inferno-os/source/browse/libbio/bgetc.c
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Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
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Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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#include <u.h>
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#include <libc.h>
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#include <bio.h>
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int
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Bgetc(Biobuf *bp)
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{
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int i;
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loop:
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i = bp->icount;
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if(i != 0) {
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bp->icount = i+1;
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return bp->ebuf[i];
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}
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if(bp->state != Bractive) {
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if(bp->state == Bracteof)
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bp->state = Bractive;
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return Beof;
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}
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/*
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* get next buffer, try to keep Bungetsize
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* characters pre-catenated from the previous
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* buffer to allow that many ungets.
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*/
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memmove(bp->bbuf-Bungetsize, bp->ebuf-Bungetsize, Bungetsize);
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i = read(bp->fid, bp->bbuf, bp->bsize);
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bp->gbuf = bp->bbuf;
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if(i <= 0) {
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bp->state = Bracteof;
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if(i < 0)
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bp->state = Binactive;
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return Beof;
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}
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if(i < bp->bsize) {
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memmove(bp->ebuf-i-Bungetsize, bp->bbuf-Bungetsize, i+Bungetsize);
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bp->gbuf = bp->ebuf-i;
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}
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bp->icount = -i;
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bp->offset += i;
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goto loop;
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}
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int
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Bungetc(Biobuf *bp)
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{
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if(bp->state == Bracteof)
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bp->state = Bractive;
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if(bp->state != Bractive)
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return Beof;
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bp->icount--;
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return 1;
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}
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