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common/rdr/OutStream.h

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+/* Copyright (C) 2002-2003 RealVNC Ltd.  All Rights Reserved.
+ *    
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This software is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
+ * USA.
+ */
+
+//
+// rdr::OutStream marshalls data into a buffer stored in RDR (RFB Data
+// Representation).
+//
+
+#ifndef __RDR_OUTSTREAM_H__
+#define __RDR_OUTSTREAM_H__
+
+#include <rdr/types.h>
+#include <rdr/InStream.h>
+#include <string.h> // for memcpy
+
+namespace rdr {
+
+  class OutStream {
+
+  protected:
+
+    OutStream() {}
+
+  public:
+
+    virtual ~OutStream() {}
+
+    // check() ensures there is buffer space for at least one item of size
+    // itemSize bytes.  Returns the number of items which fit (up to a maximum
+    // of nItems).
+
+    inline int check(int itemSize, int nItems=1)
+    {
+      if (ptr + itemSize * nItems > end) {
+        if (ptr + itemSize > end)
+          return overrun(itemSize, nItems);
+
+        nItems = (end - ptr) / itemSize;
+      }
+      return nItems;
+    }
+
+    // writeU/SN() methods write unsigned and signed N-bit integers.
+
+    inline void writeU8( U8  u) { check(1); *ptr++ = u; }
+    inline void writeU16(U16 u) { check(2); *ptr++ = u >> 8; *ptr++ = (U8)u; }
+    inline void writeU32(U32 u) { check(4); *ptr++ = u >> 24; *ptr++ = u >> 16;
+                                            *ptr++ = u >> 8; *ptr++ = u; }
+
+    inline void writeS8( S8  s) { writeU8((U8)s); }
+    inline void writeS16(S16 s) { writeU16((U16)s); }
+    inline void writeS32(S32 s) { writeU32((U32)s); }
+
+    // writeString() writes a string - a U32 length followed by the data.  The
+    // given string should be null-terminated (but the terminating null is not
+    // written to the stream).
+
+    inline void writeString(const char* str) {
+      U32 len = strlen(str);
+      writeU32(len);
+      writeBytes(str, len);
+    }
+
+    inline void pad(int bytes) {
+      while (bytes-- > 0) writeU8(0);
+    }
+
+    inline void skip(int bytes) {
+      while (bytes > 0) {
+        int n = check(1, bytes);
+        ptr += n;
+        bytes -= n;
+      }
+    }
+
+    // writeBytes() writes an exact number of bytes.
+
+    void writeBytes(const void* data, int length) {
+      const U8* dataPtr = (const U8*)data;
+      const U8* dataEnd = dataPtr + length;
+      while (dataPtr < dataEnd) {
+        int n = check(1, dataEnd - dataPtr);
+        memcpy(ptr, dataPtr, n);
+        ptr += n;
+        dataPtr += n;
+      }
+    }
+
+    // copyBytes() efficiently transfers data between streams
+
+    void copyBytes(InStream* is, int length) {
+      while (length > 0) {
+        int n = check(1, length);
+        is->readBytes(ptr, n);
+        ptr += n;
+        length -= n;
+      }
+    }
+
+    // writeOpaqueN() writes a quantity without byte-swapping.
+
+    inline void writeOpaque8( U8  u) { writeU8(u); }
+    inline void writeOpaque16(U16 u) { check(2); *ptr++ = ((U8*)&u)[0];
+                                       *ptr++ = ((U8*)&u)[1]; }
+    inline void writeOpaque32(U32 u) { check(4); *ptr++ = ((U8*)&u)[0];
+                                       *ptr++ = ((U8*)&u)[1];
+                                       *ptr++ = ((U8*)&u)[2];
+                                       *ptr++ = ((U8*)&u)[3]; }
+
+    // length() returns the length of the stream.
+
+    virtual int length() = 0;
+
+    // flush() requests that the stream be flushed.
+
+    virtual void flush() {}
+
+    // getptr(), getend() and setptr() are "dirty" methods which allow you to
+    // manipulate the buffer directly.  This is useful for a stream which is a
+    // wrapper around an underlying stream.
+
+    inline U8* getptr() { return ptr; }
+    inline U8* getend() { return end; }
+    inline void setptr(U8* p) { ptr = p; }
+
+  private:
+
+    // overrun() is implemented by a derived class to cope with buffer overrun.
+    // It ensures there are at least itemSize bytes of buffer space.  Returns
+    // the number of items which fit (up to a maximum of nItems).  itemSize is
+    // supposed to be "small" (a few bytes).
+
+    virtual int overrun(int itemSize, int nItems) = 0;
+
+  protected:
+
+    U8* ptr;
+    U8* end;
+  };
+
+}
+
+#endif