1 #include "lib9.h"
2 #include <flate.h>
3 #include "zlib.h"
4
5 int
deflatezlibblock(uchar * dst,int dsize,uchar * src,int ssize,int level,int debug)6 deflatezlibblock(uchar *dst, int dsize, uchar *src, int ssize, int level, int debug)
7 {
8 ulong adler;
9 int n;
10
11 if(dsize < 6)
12 return FlateOutputFail;
13
14 n = deflateblock(dst + 2, dsize - 6, src, ssize, level, debug);
15 if(n < 0)
16 return n;
17
18 dst[0] = ZlibDeflate | ZlibWin32k;
19
20 /* bogus zlib encoding of compression level */
21 dst[1] = ((level > 2) + (level > 5) + (level > 8)) << 6;
22
23 /* header check field */
24 dst[1] |= 31 - ((dst[0] << 8) | dst[1]) % 31;
25
26 adler = adler32(1, src, ssize);
27 dst[n + 2] = adler >> 24;
28 dst[n + 3] = adler >> 16;
29 dst[n + 4] = adler >> 8;
30 dst[n + 5] = adler;
31
32 return n + 6;
33 }
34