/* * net_io.c * $Id: net_io.c,v 1.5 2004/12/04 10:20:52 b081 Exp $ * * Copyright 2004 Bobi B., w1zard0f07@yahoo.com * * This file is part of hdl_dump. * * hdl_dump 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. * * hdl_dump 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 hdl_dump; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */#include "net_io.h"#include "byteseq.h"/**************************************************************/void /* sort-of optimal RLE compression (will not change mode unless there would be some gain) */rle_compress (const u_int8_t *input,	      u_int32_t ilength,	      u_int8_t *output,	      u_int32_t *olength) /* should have at least one byte extra for each 128 bytes */{  const u_int8_t *run_start = input;  enum curr_mode_type { cm_diff, cm_repeat } new_mode, last_mode;  u_int8_t *out = output;  u_int32_t run_len;  /* prepare */  run_len = 0;  new_mode = last_mode = cm_diff;  while (ilength)    { /* 2 bytes look-ahead */      int flush = 0;      if (last_mode == cm_diff)	{	  if (ilength >= 3)	    new_mode = (input [0] == input [1] && input [0] == input [2]) ? cm_repeat : cm_diff;	  else /* not enough data to judge */	    { /* include whatever remains in the diff */	      run_len += ilength;	      flush = 1;	      ilength = 0;	    }	}      else	new_mode = *input != *run_start ? cm_diff : cm_repeat;      flush = flush || new_mode != last_mode || ilength == 1;      if (flush && run_len > 0)	{ /* need to flush */	  if (last_mode == cm_diff)	    {	      while (run_len > 0)		{		  u_int32_t len = run_len > 128 ? 128 : run_len;		  u_int32_t i;		  *out++ = (u_int8_t) (0x00 | (len - 1));		  for (i=0; i<len; ++i)		    *out++ = *run_start++;		  run_len -= len;		}	    }	  else if (last_mode == cm_repeat)	    {	      while (run_len > 0)		{		  u_int32_t len = run_len > 128 ? 128 : run_len;		  *out++ = (u_int8_t) (0x80 | (len - 1));		  *out++ = *run_start;		  run_len -= len;		}	    }	  run_start = input;	  run_len = 0;	  new_mode = last_mode = cm_diff;	  continue; /* choose next mode */	}      last_mode = new_mode;      --ilength;      ++input;      ++run_len;    } /* loop */  *olength = out - output;}/**************************************************************/void /* RLE decompression */rle_expand (const u_int8_t *input,	    u_int32_t ilength,	    u_int8_t *output,	    u_int32_t *olength){  const u_int8_t *in = input, *end = input + ilength;  u_int8_t *out = output;  while (in < end)    {      u_int8_t rpt_byte;      int mode = *in++;      u_int32_t i, length = (mode & ~0x80) + 1;      switch (mode & 0x80)	{	case 0x00: /* difference */	  for (i=0; i<length; ++i)	    *out++ = *in++;	  break;	case 0x80: /* repetition */	  rpt_byte = *in++;	  for (i=0; i<length; ++i)	    *out++ = rpt_byte;	  break;	} /* switch */    } /* main loop */  *olength = out - output;}