/*                                       W3C Sample Code Library libwww MUX Header Definition
                                  MUX HEADER DEFINITION
                                             
 */
/*
**      (c) COPYRIGHT MIT 1995.
**      Please first read the full copyright statement in the file COPYRIGH.
*/
/*

   Define the parts of a mux header as defined by the MUX draft specification. This is not
   finalized so be warned!
   
   This module is does not contain a .cfile. It is a part of the W3C Sample Code Library.
   
 */
#ifndef HTMUXHEADER_H
#define HTMUXHEADER_H
/*

BYTE SWAPPING

   MUX is currently using little endian headers.
   
 */
#ifdef WORDS_BIGENDIAN
#define HT_WORDSWAP(a) ( ((a) << 24) | \
                         (((a) << 8) & 0x00ff0000) | \
                         (((a) >> 8) & 0x0000ff00) | \
                         ((unsigned int)(a) >> 24) )
#else
#define HT_WORDSWAP(a) ((a))
#endif
/*

THE MUX HEADER

   Simple, huh?
   
 */
typedef unsigned int  HTMuxHeader;
/*

  Generic Header flags
  
 */
#define MUX_LONG_LENGTH 0x80000000
#define MUX_CONTROL     0x40000000
/*

  Data Header Flags
  
 */
#define MUX_FLAGS       0x3C000000
#define MUX_SYN         0x20000000
#define MUX_FIN         0x10000000
#define MUX_RST         0x08000000
#define MUX_PUSH        0x04000000
/*

  Control Header Opcodes
  
 */
#define MUX_OPCODES     0x3C000000
#define MUX_STRING      0x00000000
#define MUX_STACK       0x04000000
#define MUX_FRAGMENT    0x08000000
#define MUX_CREDIT      0x0C000000
/*

  Length and Session ID
  
 */
#define MUX_SESSION     0x03FC0000
#define MUX_LENGTH      0x0003FFFF
/*

MACROS FOR BYTE SHIFTING

 */
#define MUX_SET_SID(sid)        ((sid) << 18)
#define MUX_SET_LEN(len)        ((len))
#define MUX_SET_PID             MUX_SET_LEN
#define MUX_SET_OPCODE(op)      ((op) << 26)

#define MUX_GET_SID(sid)        (((sid) & MUX_SESSION) >> 18)
#define MUX_GET_LEN(len)        ((len) & MUX_LENGTH)
#define MUX_GET_PID             MUX_GET_LEN
#define MUX_GET_OPCODE(op)      ((op) & MUX_OPCODES >> 26)
/*

HEADER ALIGNMENT

   You can force 8 byte alignment by defining this to 1. Normally, we decide pr MUX
   segment whether we have to use a long header or not.
   
 */
#define LONG_LENGTH     0                            /* 4 or 8 bytes header? */
#define MUX_IS_LONG(hdr)     ((hdr) & MUX_LONG_LENGTH)

#define MUX_ALIGN(len)       ((len) + ((4-(len)%4) % 4))
#define MUX_LONG_ALIGN(len)  ((len) + ((8-(len)%8) % 8))
/*

DEFAULT VALUES

 */
#define DEFAULT_CREDIT          4096
/*

 */
#endif
/*

   
   ___________________________________
   
                        @(#) $Id: HTMuxHeader.html,v 2.2 1997/02/16 18:42:41 frystyk Exp $
                                                                                          
    */