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