ref: c11957a7915d355d80ff7e6a21721ba05441ca29
dir: /libflate/deflatezlib.c/
#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; }