1*74a4d8c2SCharles.Forsyth #include "lib9.h"
2*74a4d8c2SCharles.Forsyth #include <flate.h>
3*74a4d8c2SCharles.Forsyth #include "zlib.h"
4*74a4d8c2SCharles.Forsyth
5*74a4d8c2SCharles.Forsyth int
deflatezlibblock(uchar * dst,int dsize,uchar * src,int ssize,int level,int debug)6*74a4d8c2SCharles.Forsyth deflatezlibblock(uchar *dst, int dsize, uchar *src, int ssize, int level, int debug)
7*74a4d8c2SCharles.Forsyth {
8*74a4d8c2SCharles.Forsyth ulong adler;
9*74a4d8c2SCharles.Forsyth int n;
10*74a4d8c2SCharles.Forsyth
11*74a4d8c2SCharles.Forsyth if(dsize < 6)
12*74a4d8c2SCharles.Forsyth return FlateOutputFail;
13*74a4d8c2SCharles.Forsyth
14*74a4d8c2SCharles.Forsyth n = deflateblock(dst + 2, dsize - 6, src, ssize, level, debug);
15*74a4d8c2SCharles.Forsyth if(n < 0)
16*74a4d8c2SCharles.Forsyth return n;
17*74a4d8c2SCharles.Forsyth
18*74a4d8c2SCharles.Forsyth dst[0] = ZlibDeflate | ZlibWin32k;
19*74a4d8c2SCharles.Forsyth
20*74a4d8c2SCharles.Forsyth /* bogus zlib encoding of compression level */
21*74a4d8c2SCharles.Forsyth dst[1] = ((level > 2) + (level > 5) + (level > 8)) << 6;
22*74a4d8c2SCharles.Forsyth
23*74a4d8c2SCharles.Forsyth /* header check field */
24*74a4d8c2SCharles.Forsyth dst[1] |= 31 - ((dst[0] << 8) | dst[1]) % 31;
25*74a4d8c2SCharles.Forsyth
26*74a4d8c2SCharles.Forsyth adler = adler32(1, src, ssize);
27*74a4d8c2SCharles.Forsyth dst[n + 2] = adler >> 24;
28*74a4d8c2SCharles.Forsyth dst[n + 3] = adler >> 16;
29*74a4d8c2SCharles.Forsyth dst[n + 4] = adler >> 8;
30*74a4d8c2SCharles.Forsyth dst[n + 5] = adler;
31*74a4d8c2SCharles.Forsyth
32*74a4d8c2SCharles.Forsyth return n + 6;
33*74a4d8c2SCharles.Forsyth }
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