lapm.c

话带数据中传真解调程序

/*
 *
 *	Stuff that does lapm (whatever that is!).
 *
 *	Copyright (c) 1999 Richard J.M. Close
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

#include "lapm.h"


void lapm_init(void)
{ 
  mnp_init_variables();
  lapm_init_variables();

  x_send_mail(0x74, 1, 0, 0);

  if (x_modem_originate == 1)
	lapm_state = 1;
  else
	lapm_state = 2;

  lapm_reset_timer();
}


bool dp_lapm_error_check(void)
{
  unsigned int eax, ecx, edx;

  eax = x_status[0x22] + (256 * x_status[0x23]); // was word_4aa42
  edx = lapm_errors;
  if (eax != edx){
	good_ff56_count = 0;
	dp_bGoodAuto = false;
  }

  if (lapm_local_busy == 1){

	if (lapm_counter < 0xc8) 
	  lapm_counter = 0x0C8;

	lapm_errors = eax;
	eax = x_status[0x20] + (256 * x_status[0x21]); // was word_4aa40
	lapm_frames = eax;
	return false;
  }

  if (S_auto_rate != 1) return false;

  ecx = x_status[0x20] + (256 * x_status[0x21]); // was word_4aa40
  if (lapm_frames != ecx)
    lapm_counter++;

  if (lapm_counter > 0x190)
    lapm_counter = 0x190;

  lapm_frames = ecx;
  if (edx == eax) return false;

  lapm_errors = eax;
  if (lapm_counter < 0x32) return true;

  lapm_counter = lapm_counter + 0xFFCE;
  return false;

}

void dp_lapm_error_check_init (void)
{
  unsigned short ax;

  ax = x_status[0x22] + (256 * x_status[0x23]); // was word_4aa42
  lapm_counter = 0xC8;
  lapm_errors = ax;
  ax = x_status[0x20] + (256 * x_status[0x21]); // was word_4aa40
  lapm_frames = ax;
}


void dp_lapm_auto_rate(void)
{

  unsigned int eax;

  if (!dp_lapm_error_check()) return;

  if (V34Mode == 0) return;

  if (cell_active) return; // Not likely!

  dp_write_dsp_ram(0x825, 0x2000);

  if (x_line_rate <= 6) return;

  dp_bFallForward = 2;
  dp_bV34WkState = 7;
  dp_rate_change_cmd (1);

  dp_state = 0x31;

  dp_timer1 = x_current_time();

  eax = (dp_read_dsp_ram(0x821) & 0xFFF7);
  eax = eax | 0x10;
  dp_write_dsp_ram(0x821, eax);

  dp_lapm_error_check_init();

  return;
}

void lapm_reset_timer(void)
{ 
  io_timer = x_current_time();
}


bool lapm_timer_expired(int how_long)
{
  if (x_elapsed_time(io_timer) >= how_long)
	return true;
  else
	return false;
}


void lapm_init_variables(void)
{
  unsigned int i, ecx;
  unsigned char* byte_ptr;

  // Set up transmit frame array.
  byte_ptr = lapm_transmit_frame + 1;
  for (ecx=9; ecx>0; ecx--) {
	*(byte_ptr - 1) = 0;
	*byte_ptr = 0;
	*(byte_ptr + 3) = 0;
	byte_ptr = byte_ptr + 0x10b;
	}

  // Set up receive queue array.
  byte_ptr = lapm_receive_queue + 2;
  for (ecx=6; ecx>0; ecx--) {
	*(byte_ptr - 2) = 0;
	*byte_ptr = 0;
	byte_ptr = byte_ptr + 0x110;
	}

  lapm_receive_frame[0] = 0;
  lapm_receive_frame[2] = 0;
  lapm_receive_frame[3] = 0;

  // Fill ecx number of dwords, at edi with eax.
  for (i=0; i<0x42; i++) {
    lapm_receive_frame[6 + (i*4)] = 0;
  }

  // Store string ?
//0003D43C		 stosb

  lapm_control_frame[0] = 0;
  lapm_control_frame[1] = 0;

  lapm_ui_frame[0] = 0;
  lapm_ui_frame[1] = 0;

  {
  unsigned char al;
  // Don't know what the hell is going on here!
  al = ETC_mode;
  al = al & 3;
  al--;
  // 2s comp.
  al = ~al + 1;
  // sbb	 al, al    sub with borrow.
  // Shouldn't this clear al?
  al = al & 0x40;
  al = al + 0x40;
  // What has al now got?
  lapm_n401 = al;
  }

  lapm_data_dlci = 0;
  lapm_dsvd_dlci = 0x20;

  lapm_vs = 0;
  lapm_va = 0;
  lapm_vr = 0;

  lapm_ns = 0;
  lapm_vrb = 0;
  lapm_vsb = 0;

  lapm_k = 8;
  lapm_t401 = 0x7D0;

  lapm_retransmit = 0;

  lapm_remote_busy = false;
  lapm_local_busy = false;
  lapm_reject_sent = false;
  lapm_rx_iframe = 0;
  lapm_iframe_on_queue = 0;

  lapm_iframe_ptr = NULL;
  lapm_rx_dte_char = 0;
  lapm_data_ptr = NULL;
  lapm_v42b_err = 0;
  lapm_state = 0;
  mnp_rx_octet_state = 0;

  lapm_odp_rptr = io_dce_rx_sptr;

  }