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- #include <u.h>
- #include <libc.h>
- #include <flate.h>
- #include "zlib.h"
- typedef struct ZRead ZRead;
- struct ZRead
- {
- ulong adler;
- void *rr;
- int (*r)(void*, void*, int);
- };
- static int
- zlread(void *vzr, void *buf, int n)
- {
- ZRead *zr;
- zr = vzr;
- n = (*zr->r)(zr->rr, buf, n);
- if(n <= 0)
- return n;
- zr->adler = adler32(zr->adler, buf, n);
- return n;
- }
- int
- deflatezlib(void *wr, int (*w)(void*, void*, int), void *rr, int (*r)(void*, void*, int), int level, int debug)
- {
- ZRead zr;
- uchar buf[4];
- int ok;
- buf[0] = ZlibDeflate | ZlibWin32k;
- /* bogus zlib encoding of compression level */
- buf[1] = ((level > 2) + (level > 5) + (level > 8)) << 6;
- /* header check field */
- buf[1] |= 31 - ((buf[0] << 8) | buf[1]) % 31;
- if((*w)(wr, buf, 2) != 2)
- return FlateOutputFail;
- zr.rr = rr;
- zr.r = r;
- zr.adler = 1;
- ok = deflate(wr, w, &zr, zlread, level, debug);
- if(ok != FlateOk)
- return ok;
- buf[0] = zr.adler >> 24;
- buf[1] = zr.adler >> 16;
- buf[2] = zr.adler >> 8;
- buf[3] = zr.adler;
- if((*w)(wr, buf, 4) != 4)
- return FlateOutputFail;
- return FlateOk;
- }
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