C# zlib.ZStream類代碼示例

        internal int deflate(ZStream strm, int flush){
            int old_flush;

            if(flush>Z_FINISH || flush<0){
                return Z_STREAM_ERROR;
            }

            if(strm.next_out == null ||
                (strm.next_in == null && strm.avail_in != 0) ||
                (status == FINISH_STATE && flush != Z_FINISH)) {
                strm.msg=z_errmsg[Z_NEED_DICT-(Z_STREAM_ERROR)];
                return Z_STREAM_ERROR;
            }
            if(strm.avail_out == 0){
                strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
                return Z_BUF_ERROR;
            }

            this.strm = strm; // just in case
            old_flush = last_flush;
            last_flush = flush;

            // Write the zlib header
            if(status == INIT_STATE) {
                int header = (Z_DEFLATED+((w_bits-8)<<4))<<8;
                int level_flags=((level-1)&0xff)>>1;

                if(level_flags>3) level_flags=3;
                header |= (level_flags<<6);
                if(strstart!=0) header |= PRESET_DICT;
                header+=31-(header % 31);

                status=BUSY_STATE;
                putShortMSB(header);


                // Save the adler32 of the preset dictionary:
                if(strstart!=0){
                    putShortMSB((int)(strm.adler>>16));
                    putShortMSB((int)(strm.adler&0xffff));
                }
                strm.adler=strm._adler.adler32(0, null, 0, 0);
            }

            // Flush as much pending output as possible
            if(pending != 0) {
                strm.flush_pending();
                if(strm.avail_out == 0) {
                    //System.out.println("  avail_out==0");
                    // Since avail_out is 0, deflate will be called again with
                    // more output space, but possibly with both pending and
                    // avail_in equal to zero. There won't be anything to do,
                    // but this is not an error situation so make sure we
                    // return OK instead of BUF_ERROR at next call of deflate:
                    last_flush = -1;
                    return Z_OK;
                }

                // Make sure there is something to do and avoid duplicate consecutive
                // flushes. For repeated and useless calls with Z_FINISH, we keep
                // returning Z_STREAM_END instead of Z_BUFF_ERROR.
            }
            else if(strm.avail_in==0 && flush <= old_flush &&
                flush != Z_FINISH) {
                strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
                return Z_BUF_ERROR;
            }

            // User must not provide more input after the first FINISH:
            if(status == FINISH_STATE && strm.avail_in != 0) {
                strm.msg=z_errmsg[Z_NEED_DICT-(Z_BUF_ERROR)];
                return Z_BUF_ERROR;
            }

            // Start a new block or continue the current one.
            if(strm.avail_in!=0 || lookahead!=0 ||
                (flush != Z_NO_FLUSH && status != FINISH_STATE)) {
                int bstate=-1;
                switch(config_table[level].func){
                    case STORED: 
                        bstate = deflate_stored(flush);
                        break;
                    case FAST: 
                        bstate = deflate_fast(flush);
                        break;
                    case SLOW: 
                        bstate = deflate_slow(flush);
                        break;
                    default:
                        break;
                }

                if (bstate==FinishStarted || bstate==FinishDone) {
                    status = FINISH_STATE;
                }
                if (bstate==NeedMore || bstate==FinishStarted) {
                    if(strm.avail_out == 0) {
                        last_flush = -1; // avoid BUF_ERROR next call, see above
                    }
                    return Z_OK;
//.........這裏部分代碼省略.........

 internal void init(int bl, int bd,
     int[] tl, int tl_index,
     int[] td, int td_index, ZStream z)
 {
     mode=START;
     lbits=(byte)bl;
     dbits=(byte)bd;
     ltree=tl;
     ltree_index=tl_index;
     dtree = td;
     dtree_index=td_index;
     tree=null;
 }

 // Returns true if inflate is currently at the end of a block generated
 // by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
 // implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
 // but removes the length bytes of the resulting empty stored block. When
 // decompressing, PPP checks that at the end of input packet, inflate is
 // waiting for these length bytes.
 internal int inflateSyncPoint(ZStream z){
     if(z == null || z.istate == null || z.istate.blocks == null)
         return Z_STREAM_ERROR;
     return z.istate.blocks.sync_point();
 }

 internal void free(ZStream z)
 {
     //  ZFREE(z, c);
 }

        internal int inflateInit(ZStream z, int w){
            z.msg = null;
            blocks = null;

            // handle undocumented nowrap option (no zlib header or check)
            nowrap = 0;
            if(w < 0){
                w = - w;
                nowrap = 1;
            }

            // set window size
            if(w<8 ||w>15){
                inflateEnd(z);
                return Z_STREAM_ERROR;
            }
            wbits=w;

            z.istate.blocks=new InfBlocks(z, 
                z.istate.nowrap!=0 ? null : this,
                1<<w);

            // reset state
            inflateReset(z);
            return Z_OK;
        }

        internal int inflateSetDictionary(ZStream z, byte[] dictionary, int dictLength){
            int index=0;
            int length = dictLength;
            if(z==null || z.istate == null|| z.istate.mode != DICT0)
                return Z_STREAM_ERROR;

            if(z._adler.adler32(1L, dictionary, 0, dictLength)!=z.adler){
                return Z_DATA_ERROR;
            }

            z.adler = z._adler.adler32(0, null, 0, 0);

            if(length >= (1<<z.istate.wbits)){
                length = (1<<z.istate.wbits)-1;
                index=dictLength - length;
            }
            z.istate.blocks.set_dictionary(dictionary, index, length);
            z.istate.mode = BLOCKS;
            return Z_OK;
        }

        internal int inflate_trees_dynamic(int nl,   // number of literal/length codes
            int nd,   // number of distance codes
            int[] c,  // that many (total) code lengths
            int[] bl, // literal desired/actual bit depth
            int[] bd, // distance desired/actual bit depth 
            int[] tl, // literal/length tree result
            int[] td, // distance tree result
            int[] hp, // space for trees
            ZStream z // for messages
            ){
            int result;

            // build literal/length tree
            initWorkArea(288);
            hn[0]=0;
            result = huft_build(c, 0, nl, 257, cplens, cplext, tl, bl, hp, hn, v);
            if (result != Z_OK || bl[0] == 0){
                if(result == Z_DATA_ERROR){
                    z.msg = "oversubscribed literal/length tree";
                }
                else if (result != Z_MEM_ERROR){
                    z.msg = "incomplete literal/length tree";
                    result = Z_DATA_ERROR;
                }
                return result;
            }

            // build distance tree
            initWorkArea(288);
            result = huft_build(c, nl, nd, 0, cpdist, cpdext, td, bd, hp, hn, v);

            if (result != Z_OK || (bd[0] == 0 && nl > 257)){
                if (result == Z_DATA_ERROR){
                    z.msg = "oversubscribed distance tree";
                }
                else if (result == Z_BUF_ERROR) {
                    z.msg = "incomplete distance tree";
                    result = Z_DATA_ERROR;
                }
                else if (result != Z_MEM_ERROR){
                    z.msg = "empty distance tree with lengths";
                    result = Z_DATA_ERROR;
                }
                return result;
            }

            return Z_OK;
        }

 internal static int inflate_trees_fixed(int[] bl,  //literal desired/actual bit depth
     int[] bd,  //distance desired/actual bit depth
     int[][] tl,//literal/length tree result
     int[][] td,//distance tree result 
     ZStream z  //for memory allocation
     ){
     bl[0]=fixed_bl;
     bd[0]=fixed_bd;
     tl[0]=fixed_tl;
     td[0]=fixed_td;
     return Z_OK;
 }

        internal int inflate_trees_bits(int[] c,  // 19 code lengths
            int[] bb, // bits tree desired/actual depth
            int[] tb, // bits tree result
            int[] hp, // space for trees
            ZStream z // for messages
            ){
            int result;
            initWorkArea(19);
            hn[0]=0;
            result = huft_build(c, 0, 19, 19, null, null, tb, bb, hp, hn, v);

            if(result == Z_DATA_ERROR){
                z.msg = "oversubscribed dynamic bit lengths tree";
            }
            else if(result == Z_BUF_ERROR || bb[0] == 0){
                z.msg = "incomplete dynamic bit lengths tree";
                result = Z_DATA_ERROR;
            }
            return result;
        }

 internal int deflateInit(ZStream strm, int level, int bits){
     return deflateInit2(strm, level, Z_DEFLATED, bits, DEF_MEM_LEVEL,
         Z_DEFAULT_STRATEGY);
 }

 internal int inflateEnd(ZStream z){
     if(blocks != null)
         blocks.free(z);
     blocks=null;
     //    ZFREE(z, z->state);
     return Z_OK;
 }

        internal int inflate(ZStream z, int f){
            int r;
            int b;

            if(z == null || z.istate == null || z.next_in == null)
                return Z_STREAM_ERROR;
            f = f == Z_FINISH ? Z_BUF_ERROR : Z_OK;
            r = Z_BUF_ERROR;
            while (true){
                //System.out.println("mode: "+z.istate.mode);
                switch (z.istate.mode){
                    case METHOD:

                        if(z.avail_in==0)return r;r=f;

                        z.avail_in--; z.total_in++;
                        if(((z.istate.method = z.next_in[z.next_in_index++])&0xf)!=Z_DEFLATED){
                            z.istate.mode = BAD;
                            z.msg="unknown compression method";
                            z.istate.marker = 5;       // can't try inflateSync
                            break;
                        }
                        if((z.istate.method>>4)+8>z.istate.wbits){
                            z.istate.mode = BAD;
                            z.msg="invalid window size";
                            z.istate.marker = 5;       // can't try inflateSync
                            break;
                        }
                        z.istate.mode=FLAG;
                        goto case FLAG;
                    case FLAG:

                        if(z.avail_in==0)return r;r=f;

                        z.avail_in--; z.total_in++;
                        b = (z.next_in[z.next_in_index++])&0xff;

                        if((((z.istate.method << 8)+b) % 31)!=0){
                            z.istate.mode = BAD;
                            z.msg = "incorrect header check";
                            z.istate.marker = 5;       // can't try inflateSync
                            break;
                        }

                        if((b&PRESET_DICT)==0){
                            z.istate.mode = BLOCKS;
                            break;
                        }
                        z.istate.mode = DICT4;
                        goto case DICT4;
                    case DICT4:

                        if(z.avail_in==0)return r;r=f;

                        z.avail_in--; z.total_in++;
                        z.istate.need=((z.next_in[z.next_in_index++]&0xff)<<24)&0xff000000L;
                        z.istate.mode=DICT3;
                        goto case DICT3;
                    case DICT3:

                        if(z.avail_in==0)return r;r=f;

                        z.avail_in--; z.total_in++;
                        z.istate.need+=((z.next_in[z.next_in_index++]&0xff)<<16)&0xff0000L;
                        z.istate.mode=DICT2;
                        goto case DICT2;
                    case DICT2:

                        if(z.avail_in==0)return r;r=f;

                        z.avail_in--; z.total_in++;
                        z.istate.need+=((z.next_in[z.next_in_index++]&0xff)<<8)&0xff00L;
                        z.istate.mode=DICT1;
                        goto case DICT1;
                    case DICT1:

                        if(z.avail_in==0)return r;r=f;

                        z.avail_in--; z.total_in++;
                        z.istate.need += (z.next_in[z.next_in_index++]&0xffL);
                        z.adler = z.istate.need;
                        z.istate.mode = DICT0;
                        return Z_NEED_DICT;
                    case DICT0:
                        z.istate.mode = BAD;
                        z.msg = "need dictionary";
                        z.istate.marker = 0;       // can try inflateSync
                        return Z_STREAM_ERROR;
                    case BLOCKS:

                        r = z.istate.blocks.proc(z, r);
                        if(r == Z_DATA_ERROR){
                            z.istate.mode = BAD;
                            z.istate.marker = 0;     // can try inflateSync
                            break;
                        }
                        if(r == Z_OK){
                            r = f;
                        }
                        if(r != Z_STREAM_END){
//.........這裏部分代碼省略.........

        internal int deflateInit2(ZStream strm, int level, int method,  int windowBits,
            int memLevel, int strategy){
            int noheader = 0;
            //    byte[] my_version=ZLIB_VERSION;

            //
            //  if (version == null || version[0] != my_version[0]
            //  || stream_size != sizeof(z_stream)) {
            //  return Z_VERSION_ERROR;
            //  }

            strm.msg = null;

            if (level == Z_DEFAULT_COMPRESSION) level = 6;

            if (windowBits < 0) { // undocumented feature: suppress zlib header
                noheader = 1;
                windowBits = -windowBits;
            }

            if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || 
                method != Z_DEFLATED ||
                windowBits < 9 || windowBits > 15 || level < 0 || level > 9 ||
                strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
                return Z_STREAM_ERROR;
            }

            strm.dstate = (Deflate)this;

            this.noheader = noheader;
            w_bits = windowBits;
            w_size = 1 << w_bits;
            w_mask = w_size - 1;

            hash_bits = memLevel + 7;
            hash_size = 1 << hash_bits;
            hash_mask = hash_size - 1;
            hash_shift = ((hash_bits+MIN_MATCH-1)/MIN_MATCH);

            window = new byte[w_size*2];
            prev = new short[w_size];
            head = new short[hash_size];

            lit_bufsize = 1 << (memLevel + 6); // 16K elements by default

            // We overlay pending_buf and d_buf+l_buf. This works since the average
            // output size for (length,distance) codes is <= 24 bits.
            pending_buf = new byte[lit_bufsize*4];
            pending_buf_size = lit_bufsize*4;

            d_buf = lit_bufsize/2;
            l_buf = (1+2)*lit_bufsize;

            this.level = level;

            //System.out.println("level="+level);

            this.strategy = strategy;
            this.method = (byte)method;

            return deflateReset(strm);
        }

        internal int inflateSync(ZStream z){
            int n;       // number of bytes to look at
            int p;       // pointer to bytes
            int m;       // number of marker bytes found in a row
            long r, w;   // temporaries to save total_in and total_out

            // set up
            if(z == null || z.istate == null)
                return Z_STREAM_ERROR;
            if(z.istate.mode != BAD){
                z.istate.mode = BAD;
                z.istate.marker = 0;
            }
            if((n=z.avail_in)==0)
                return Z_BUF_ERROR;
            p=z.next_in_index;
            m=z.istate.marker;

            // search
            while (n!=0 && m < 4){
                if(z.next_in[p] == mark[m]){
                    m++;
                }
                else if(z.next_in[p]!=0){
                    m = 0;
                }
                else{
                    m = 4 - m;
                }
                p++; n--;
            }

            // restore
            z.total_in += p-z.next_in_index;
            z.next_in_index = p;
            z.avail_in = n;
            z.istate.marker = m;

            // return no joy or set up to restart on a new block
            if(m != 4){
                return Z_DATA_ERROR;
            }
            r=z.total_in;  w=z.total_out;
            inflateReset(z);
            z.total_in=r;  z.total_out = w;
            z.istate.mode = BLOCKS;
            return Z_OK;
        }

        internal int deflateReset(ZStream strm){
            strm.total_in = strm.total_out = 0;
            strm.msg = null; //
            strm.data_type = Z_UNKNOWN;

            pending = 0;
            pending_out = 0;

            if(noheader < 0) {
                noheader = 0; // was set to -1 by deflate(..., Z_FINISH);
            }
            status = (noheader!=0) ? BUSY_STATE : INIT_STATE;
            strm.adler=strm._adler.adler32(0, null, 0, 0);

            last_flush = Z_NO_FLUSH;

            tr_init();
            lm_init();
            return Z_OK;
        }