--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/g23m-gsm/dl/dl_com.c	Fri Oct 16 06:25:50 2020 +0000
@@ -0,0 +1,1327 @@
+/*
++-----------------------------------------------------------------------------
+|  Project :
+|  Modul   :
++-----------------------------------------------------------------------------
+|  Copyright 2002 Texas Instruments Berlin, AG
+|                 All rights reserved.
+|
+|                 This file is confidential and a trade secret of Texas
+|                 Instruments Berlin, AG
+|                 The receipt of or possession of this file does not convey
+|                 any rights to reproduce or disclose its contents or to
+|                 manufacture, use, or sell anything it may describe, in
+|                 whole, or in part, without the specific written consent of
+|                 Texas Instruments Berlin, AG.
++-----------------------------------------------------------------------------
+|  Purpose :  This Modul defines the common functions
+|             for the component DL of the mobile station.
++-----------------------------------------------------------------------------
+*/
+
+#ifndef DL_COM_C
+#define DL_COM_C
+
+#define ENTITY_DL
+
+/*==== INCLUDES ===================================================*/
+#include "typedefs.h"
+#include <string.h>
+#include "vsi.h"
+#if !defined(DL_2TO1)
+//#include "p_8010_147_l1_include.h"
+#endif  /* DL_2TO1 */
+#include "pconst.cdg"
+#include "custom.h"
+#include "gsm.h"
+#include "mon_dl.h"
+#include "prim.h"
+#include "pei.h"
+#include "tok.h"
+#include "ccdapi.h"
+#include "dl.h"
+#include "dl_trc.h"
+#include "dl_em.h"
+
+/*==== TEST TRACE ===================================================*/
+#define TEST_ENTITY_DL
+
+/*==== EXPORT =====================================================*/
+
+/*==== PRIVAT =====================================================*/
+LOCAL void com_build_frame            ( 
+                                        UBYTE                    ch_type,
+                                        UBYTE                    type,
+                                        UBYTE                    sapi,
+                                        UBYTE                    cr,
+                                        UBYTE                    ns,
+                                        UBYTE                    nr,
+                                        UBYTE                    p_bit,
+                                        UBYTE                    length,
+                                        UBYTE                    m_bit,
+                                        UBYTE                  * pInfoBuffer,
+                                        UBYTE                    InfoOffset);
+
+/*==== VARIABLES ==================================================*/
+
+/*==== FUNCTIONS ==================================================*/
+
+/*
++------------------------------------------------------------------------------
+| Function    : com_free_pointer
++------------------------------------------------------------------------------
+| Description : frees the pointer given by parameter
++------------------------------------------------------------------------------
+*/
+GLOBAL void com_free_pointer (void * pointer)
+{
+  GET_INSTANCE_DATA;
+  TRACE_EVENT_WIN_P1 ("com_free_pointer(,p=%08x)", pointer);
+
+#if defined(INVOKE_SIGNAL)
+  if (dl_data->interrupt_context)
+  {
+    sig_invoke_com_free_pointer (pointer);
+    return;
+  }
+#endif  /* INVOKE_SIGNAL */
+
+TRACE_ASSERT(pointer);
+  MY_PFREE (pointer);
+}
+
+GLOBAL void com_free_queue_buffer (T_QUEUE * queue, USHORT index)
+{
+  T_DL_DATA_REQ **pp;
+
+  switch (index)
+  {
+    default:
+      if (index <= INDEX_MAX_STORE_BUFFER)
+        pp = &queue->store_buffer[index];
+      else
+        pp = NULL;
+      break;
+    case INDEX_SENDING_BUFFER:
+      pp = &queue->sending_buffer;
+      break;
+    case INDEX_SWITCH_BUFFER:
+      pp = &queue->switch_buffer;
+      break;
+  }
+  if (pp AND *pp)
+  {
+    COM_FREE_POINTER (*pp);
+    *pp = NULL;
+  }
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_clear_queue     |
++--------------------------------------------------------------------+
+
+  PURPOSE : Clearing a DL queue.
+
+*/
+
+GLOBAL void com_clear_queue (UBYTE sapi)
+{
+  GET_INSTANCE_DATA;
+  USHORT i;
+  T_QUEUE *queue;
+  TRACE_FUNCTION ("com_clear_queue()");
+
+  if (sapi EQ PS_SAPI_0)
+  {
+    queue = &dl_data->dcch0_queue;
+  }
+  else
+  {
+    queue = &dl_data->dcch3_queue;
+  }
+
+  for (i=0;i<MAX_QUEUED_MESSAGES;i++)
+    if (queue->store_buffer [i] NEQ NULL)
+    {
+      COM_FREE_QUEUE_BUFFER (queue, i);
+    }
+
+  if (queue->sending_buffer NEQ NULL)
+  {
+    COM_FREE_QUEUE_BUFFER (queue, INDEX_SENDING_BUFFER);
+  }
+
+  if (queue->switch_buffer NEQ NULL)
+  {
+    COM_FREE_QUEUE_BUFFER (queue, INDEX_SWITCH_BUFFER);
+  }
+  queue->act_length = queue->act_offset = 0;
+  queue->no_of_stored_messages = 0;
+  memset (&queue->transmit_buffer, 0, sizeof (T_FRAME));
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_restore_queue   |
++--------------------------------------------------------------------+
+
+  PURPOSE : Restoring a DL queue. If a new connection shall be
+            established, the message (ASSIGNMENT or HANDOVER COMPLETE)
+            is transmitted first. So the message is stored in the
+            switch buffer. A previously not complete send message will
+            be put back into the storing buffer.
+
+*/
+
+GLOBAL void com_restore_queue (UBYTE sapi, T_DL_DATA_REQ* est_req)
+{
+  GET_INSTANCE_DATA;
+  T_QUEUE *queue = sapi EQ PS_SAPI_0 ? &dl_data->dcch0_queue:&dl_data->dcch3_queue;
+
+  TRACE_FUNCTION ("com_restore_queue()");
+
+  if (queue->switch_buffer NEQ NULL)
+  {
+    TRACE_EVENT_WIN ("free old switch_buffer");
+    COM_FREE_QUEUE_BUFFER (queue, INDEX_SWITCH_BUFFER);
+  }
+
+  if (est_req AND est_req->sdu.l_buf)
+  {
+    PPASS (est_req, data_req, DL_DATA_REQ);
+    queue->switch_buffer = data_req; /* only valid sdu */
+
+    TRACE_EVENT_WIN_P2 ("new fill of switch_buffer:%p l=%u",
+      data_req, est_req->sdu.l_buf>>3);
+  }
+
+  if (queue->sending_buffer NEQ NULL)
+  {
+    TRACE_EVENT_WIN ("restore sending_buffer");
+    queue->act_length     = queue->sending_buffer->sdu.l_buf;
+    queue->act_offset     = queue->sending_buffer->sdu.o_buf;
+  }
+  TRACE_EVENT_WIN ("delete transmit_buffer");
+  memset (&queue->transmit_buffer, 0, sizeof (T_FRAME));
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_recover_queue   |
++--------------------------------------------------------------------+
+
+  PURPOSE : Recover a DL queue after a Reject condition.
+
+*/
+
+GLOBAL void com_recover_queue (UBYTE sapi)
+{
+  GET_INSTANCE_DATA;
+  T_QUEUE *queue = sapi EQ PS_SAPI_0 ? &dl_data->dcch0_queue:&dl_data->dcch3_queue;
+
+  TRACE_FUNCTION ("com_recover_queue()");
+
+  if (queue->sending_buffer NEQ NULL)
+  {
+    if(queue->act_length NEQ 0) /* For last buf, act_length is set to 0 */
+    {                           /* and the act_offset is not modified */
+      queue->act_offset    -= queue->transmit_buffer.l_buf;
+    }
+    queue->act_length    += queue->transmit_buffer.l_buf;
+  }
+  memset (&queue->transmit_buffer, 0, sizeof (T_FRAME));
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_read_queue      |
++--------------------------------------------------------------------+
+
+  PURPOSE : Reading the next segment of a message from a DL queue.
+            If a message in the switch buffer is stored, this message
+            is used. If a message is stored in the sending buffer which
+            is not send completely the next segment is copied to the
+            transmit buffer. Else the next sending buffer is copied from
+            the store buffer of the queue. The first segment of this
+            message is copied to the transfer buffer.
+
+*/
+
+GLOBAL void com_read_queue (UBYTE ch_type, UBYTE sapi,
+                            UBYTE * m_bit)
+{
+  GET_INSTANCE_DATA;
+  USHORT   i;
+  USHORT   length, bit_length;
+  T_DL_DATA_REQ * dl_data_req;
+  T_QUEUE  *queue = sapi EQ PS_SAPI_0 ? &dl_data->dcch0_queue : &dl_data->dcch3_queue;
+
+  TRACE_FUNCTION ("com_read_queue()");
+  TRACE_EVENT_WIN_P1 ("read sapi_%u_queue", sapi);
+
+  switch (ch_type)
+  {
+    case L2_CHANNEL_SDCCH:
+      length = N201_SDCCH;
+      break;
+
+    case L2_CHANNEL_SACCH:
+      length = N201_SACCH;
+      break;
+
+    case L2_CHANNEL_FACCH_F:
+    case L2_CHANNEL_FACCH_H:
+      length = N201_FACCH;
+      break;
+
+    default:
+      length = 0;
+      bit_length = 0;
+      break;
+  }
+  bit_length = length << 3;
+
+  if (queue->switch_buffer NEQ NULL)
+  {
+    T_DL_DATA_REQ *switch_buffer = queue->switch_buffer;
+
+    TRACE_EVENT_WIN_P2 ("fill transmit_buffer with bytes %u-%u of switch_buffer, no bytes left",
+      (switch_buffer->sdu.o_buf>>3),
+      ((switch_buffer->sdu.o_buf+switch_buffer->sdu.l_buf)>>3)-1);
+
+    queue->m_bit = * m_bit = 0;
+    queue->transmit_buffer.o_buf = 24;
+    queue->transmit_buffer.l_buf = switch_buffer->sdu.l_buf;
+    for (i=0;i<(switch_buffer->sdu.l_buf>>3);i++)
+      queue->transmit_buffer.buf[i+3] =
+        switch_buffer->sdu.buf[i+(switch_buffer->sdu.o_buf>>3)];
+
+    /*
+    should be freed first after acknowledgement!
+    COM_FREE_QUEUE_BUFFER (dl_data, queue, INDEX_SWITCH_BUFFER);
+    */
+    return;
+  }
+  else
+  {
+    if (queue->act_length EQ 0)
+    {
+      if (queue->sending_buffer NEQ NULL)
+      {
+        COM_FREE_QUEUE_BUFFER (queue, INDEX_SENDING_BUFFER);
+      }
+      queue->sending_buffer = queue->store_buffer[0];
+      queue->act_offset     = queue->sending_buffer->sdu.o_buf;
+      queue->act_length     = queue->sending_buffer->sdu.l_buf;
+      TRACE_EVENT_WIN_P2 ("fill sending_buffer with bytes %u-%u of store_buffer[0]",
+        (queue->sending_buffer->sdu.o_buf>>3),
+        ((queue->sending_buffer->sdu.o_buf+queue->sending_buffer->sdu.l_buf)>>3)-1);
+
+      for (i=0;i<MAX_QUEUED_MESSAGES-1;i++)
+        queue->store_buffer[i] = queue->store_buffer[i+1];
+      queue->no_of_stored_messages--;
+
+      TRACE_EVENT_WIN_P1 ("left no_of_stored_messages=%u", queue->no_of_stored_messages);
+    }
+    dl_data_req = queue->sending_buffer;
+  }
+
+
+  if (queue->act_length > bit_length)
+  { /*
+     * lint Info 702: Shift right of signed quantity:
+     * not possible because of the compare one line before
+     */
+    TRACE_EVENT_WIN_P3 ("fill transmit_buffer with bytes %u-%u of sending_buffer, %u bytes left",
+      queue->act_offset>>3, (queue->act_offset>>3)+length-1,
+      (queue->act_length-bit_length)>>3);
+
+    queue->m_bit = * m_bit = 1;
+    queue->transmit_buffer.o_buf = 24;
+    queue->transmit_buffer.l_buf = bit_length;
+    for (i=0;i<length;i++)
+      queue->transmit_buffer.buf[i+3] =
+        dl_data_req->sdu.buf[i+(queue->act_offset>>3)];
+    queue->act_offset += bit_length;
+    queue->act_length -= bit_length;
+  }
+  else
+  {
+    TRACE_EVENT_WIN_P2 ("fill transmit_buffer with bytes %u-%u of sending_buffer, no bytes left",
+      queue->act_offset>>3, ((queue->act_offset+queue->act_length)>>3)-1);
+
+    queue->m_bit = * m_bit = 0;
+    queue->transmit_buffer.o_buf = 24;
+    queue->transmit_buffer.l_buf = queue->act_length;
+    for (i=0;i<(queue->act_length>>3);i++)
+      queue->transmit_buffer.buf[i+3] =
+        dl_data_req->sdu.buf[i+(queue->act_offset>>3)];
+    queue->act_length = 0;
+  }
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_store_queue     |
++--------------------------------------------------------------------+
+
+  PURPOSE : Storing a message into the queue.
+
+*/
+
+GLOBAL void com_store_queue (UBYTE sapi, T_DL_DATA_REQ * data_req)
+{
+  GET_INSTANCE_DATA;
+  T_QUEUE * queue;
+
+  TRACE_FUNCTION ("com_store_queue()");
+
+  if (sapi EQ PS_SAPI_0)
+  {
+    queue = &dl_data->dcch0_queue;
+  }
+  else
+  {
+    queue = &dl_data->dcch3_queue;
+  }
+
+  if (queue->no_of_stored_messages < MAX_QUEUED_MESSAGES)
+  {
+    queue->store_buffer[queue->no_of_stored_messages++] = data_req;
+    TRACE_EVENT_WIN_P3 ("sapi_%u_queue: add entry with %u bytes, no_of_stored_messages=%u",
+      sapi, data_req->sdu.l_buf>>3, queue->no_of_stored_messages);
+  }
+  else
+  {
+    COM_FREE_POINTER (data_req);
+    TRACE_EVENT_WIN_P1 ("sapi_%u_queue overflowed", sapi);
+  }
+}
+
+/*
++------------------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)        MODULE  : DL_COM                              |
+| STATE   : code                 ROUTINE : com_queue_awaiting_transmission     |
++------------------------------------------------------------------------------+
+
+  PURPOSE : The function checks whether any segment has to sended.
+            Function returns TRUE if a frame/segment is awaiting transmission.
+            Function returns FALSE if not.
+
+*/
+
+GLOBAL BOOL com_queue_awaiting_transmission (UBYTE sapi)
+{
+  GET_INSTANCE_DATA;
+  T_QUEUE * queue;
+  BOOL      ret;
+
+  TRACE_EVENT_WIN_P1 ("com_queue_awaiting_transmission(SAPI=%u)", sapi);
+
+  queue = (sapi EQ PS_SAPI_0) ? &dl_data->dcch0_queue : &dl_data->dcch3_queue;
+  if (sapi EQ PS_SAPI_0)
+  {
+    queue = &dl_data->dcch0_queue;
+  }
+  else
+  {
+    queue = &dl_data->dcch3_queue;
+  }
+  if (queue->switch_buffer NEQ NULL)
+  {
+    TRACE_EVENT_WIN_P1 ("sapi_%u_queue: switch_buffer is awaiting", sapi);
+    ret = TRUE;
+  }
+  else
+  {
+    if (queue->act_length EQ 0)
+    {
+      ret = queue->no_of_stored_messages NEQ 0;
+      if (ret)
+      {
+        TRACE_EVENT_WIN_P2 ("sapi_%u_queue: store_buffer is awaiting (no_of_stored_messages=%u)",
+          sapi, queue->no_of_stored_messages);
+      }
+    }
+    else
+    {
+      TRACE_EVENT_WIN_P2 ("sapi_%u_queue: transmit_buffer is awaiting (%u bytes)",
+        sapi, queue->act_length);
+      ret = TRUE;
+    }
+  }
+
+  return ret;
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_leave_dedicated |
++--------------------------------------------------------------------+
+
+  PURPOSE : Leave dedicated mode.
+
+*/
+
+GLOBAL void com_leave_dedicated (UBYTE ch_type)
+{
+  GET_INSTANCE_DATA;
+  dl_data->RR_dedicated = FALSE; /* RR is leaving the dedicated mode */
+  DL_OFFLINE_TRACE (TRACE_DL_EVENT, TRACE_CH_UNKNOWN, ch_type, "RR_dedicated:=FALSE");
+}
+
+/*
++-----------------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM                       |
+| STATE   : code                       ROUTINE : possible_reset_dcch0_ch_type |
++-----------------------------------------------------------------------------+
+
+  PURPOSE : Reset dedicated channel.
+
+*/
+GLOBAL void possible_reset_dcch0_ch_type (void)
+{
+  GET_INSTANCE_DATA;
+  if (
+      #if defined(DELAYED_SABM)
+        (dl_data->dcch0_sabm_flag NEQ NOT_PRESENT_8BIT) AND
+      #endif /* DELAYED_SABM */
+      #if defined(DELAYED_RELEASE_IND)
+        (dl_data->release_ind_ch_type NEQ NOT_PRESENT_8BIT) AND
+      #endif /* DELAYED_RELEASE_IND */
+      (dl_data->state[C_DCCH0] <= STATE_IDLE_DL) AND
+      (dl_data->cch[C_DCCH0].vtx EQ EMPTY_CMD))
+  {
+    TRACE_EVENT_WIN_P1 ("reset dcch0_ch_type=%s ->0", CH_TYPE_NAME[dl_data->dcch0_ch_type]);
+    dl_data->dcch0_ch_type = 0;
+  }
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_compare_L3_msg  |
++--------------------------------------------------------------------+
+
+  PURPOSE : The function compares two layer 3 messages.
+
+
+*/
+
+GLOBAL UBYTE com_compare_L3_msg (T_DL_DATA_REQ * data_ind1, UBYTE * data_ind2)
+{
+  USHORT length1;
+  USHORT length2;
+  USHORT pos1;
+  USHORT pos2;
+  USHORT i;
+
+  TRACE_FUNCTION ("com_compare_L3_msg()");
+
+  /*
+   * Calculates Length of SABM and UA layer 3 message
+   */
+  length1 = data_ind1->sdu.l_buf>>3;    /* length of l3 msg inside SABM frame */
+  length2 = ((data_ind2[2] & 0xFC)>>2); /* length of l3 msg inside UA frame */
+
+  if (length1 NEQ length2)
+    return FALSE;
+
+  pos1   = data_ind1->sdu.o_buf >> 3;
+  pos2   = 3;
+
+
+  for (i=0; i<length1; i++)
+  {
+    if (data_ind1->sdu.buf[i+pos1] NEQ data_ind2[i+pos2])
+    {
+#if defined(DL_TRACE_ENABLED)
+      UBYTE sapi = data_ind1->sapi;
+      UBYTE trace_channel = TRACE_CH_UNKNOWN;
+      switch (data_ind1->ch_type)
+      {
+      case L2_CHANNEL_SDCCH:
+        if (sapi EQ PS_SAPI_0)
+          trace_channel = C_DCCH0;
+        else if (sapi EQ PS_SAPI_3)
+          trace_channel = C_DCCH3;
+        break;
+      case L2_CHANNEL_FACCH_F:
+      case L2_CHANNEL_FACCH_H:
+          trace_channel = C_DCCH0;
+        break;
+      default:
+        break;
+      }/* endswitch chan */
+      DL_OFFLINE_TRACE(TRACE_DL_EVENT, trace_channel, data_ind1->ch_type, "UA doesn´t match");
+#endif  /* DL_TRACE_ENABLED */
+      return FALSE;
+    }
+  }
+  return TRUE;
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_concatenate     |
++--------------------------------------------------------------------+
+
+  PURPOSE : Concenate an imcoming segment.
+
+*/
+
+GLOBAL void com_concatenate (T_DL_DATA_IND ** in_msg,
+                             UBYTE * new_data_in)
+{
+  GET_INSTANCE_DATA;
+  USHORT   end_pos;
+  USHORT   length;
+  USHORT   start_pos;
+  #define  L2_HEADER_BYTESIZE  3
+
+  TRACE_FUNCTION ("com_concatenate()");
+
+#if defined(INVOKE_SIGNAL)
+    if (dl_data->interrupt_context)
+    {
+      sig_invoke_com_concatenate (in_msg, new_data_in);
+      return;
+    }
+#endif  /* INVOKE_SIGNAL */
+
+  length    = new_data_in[2] >> 2;
+
+  if (*in_msg EQ NULL)
+  {
+    /*
+     * Nothing stored yet
+     */
+    USHORT len_in_bits = (length + L2_HEADER_BYTESIZE) << 3;
+    PALLOC_SDU (first_data, DL_DATA_IND, len_in_bits );
+
+    first_data->sdu.l_buf  = length << 3;         /* = length * BITS_PER_BYTE */
+    first_data->sdu.o_buf  = L2_HEADER_BYTESIZE << 3;/* = L2_HEADER_BYTESIZE * BITS_PER_BYTE */
+    /*lint -e419 (Warning -- Apparent data overrun) */
+    memset (&first_data->sdu.buf[0], 0, L2_HEADER_BYTESIZE);
+    /*lint +e419 (Warning -- Apparent data overrun) */
+    /*lint -e416 (Warning -- creation of out-of-bounds pointer) */
+    memcpy (&first_data->sdu.buf[L2_HEADER_BYTESIZE],
+            &new_data_in[L2_HEADER_BYTESIZE],
+            length);
+    /*lint +e416 (Warning -- creation of out-of-bounds pointer) */
+    *in_msg = first_data;
+  }
+  else
+  {
+    T_DL_DATA_IND *previous_data = *in_msg;
+
+    start_pos = previous_data->sdu.l_buf + previous_data->sdu.o_buf;
+    end_pos   = (length << 3) + start_pos;
+    {
+      PALLOC_SDU (entire_data, DL_DATA_IND, end_pos );
+
+      /*lint -e415 (Warning -- access of out-of-bounds pointer) */
+      memcpy (entire_data->sdu.buf, previous_data->sdu.buf, start_pos >> 3);
+      memcpy (&entire_data->sdu.buf[start_pos >> 3],
+              &new_data_in[L2_HEADER_BYTESIZE],
+              length);
+      /*lint +e415 (Warning -- access of out-of-bounds pointer) */
+
+      entire_data->sdu.l_buf   = previous_data->sdu.l_buf + (length << 3);
+      entire_data->sdu.o_buf   = previous_data->sdu.o_buf;
+
+      COM_FREE_POINTER (*in_msg);
+      *in_msg = entire_data;
+    }
+  }
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)              MODULE  : DL_COM              |
+| STATE   : code                       ROUTINE : com_check_nr        |
++--------------------------------------------------------------------+
+
+  PURPOSE : Check the receive number.
+
+*/
+
+GLOBAL UBYTE com_check_nr (UBYTE va, UBYTE vs, UBYTE nr)
+{
+  BYTE a,b;
+
+  TRACE_FUNCTION ("com_check_nr()");
+  /*
+   * under GSM 4.06 subclause 3.5.2.3:
+   * nr is valid, if and only if ((nr-va) mod 8) <= ((vs-va) mod 8)
+   */
+  a = (nr+8-va) & 7;
+  b = (vs+8-va) & 7;
+
+  return (a <= b);
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_prepare_DISC      |
++--------------------------------------------------------------------+
+
+  PURPOSE : Prepares a DISC command.
+
+*/
+
+GLOBAL void com_prepare_DISC (UBYTE channel, UBYTE sapi)
+{
+  GET_INSTANCE_DATA;
+  T_CCH *pcch = &dl_data->cch[channel];
+
+  pcch->vtx           = DISC_CMD;
+  pcch->time_flag     = TRUE;
+  pcch->T200_counter  = 0;
+  pcch->rc            = 0;
+  set_channel_state (channel, STATE_AWAITING_RELEASE);
+  TRACE_EVENT_WIN_P3 ("RELEASE_REQ: %s SAPI=%u vtx=%s", CH_TYPE_NAME[pcch->ch_type],
+                                      sapi, VTX_NAME[pcch->vtx]);
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_build_UA_response |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build an UA response.
+
+*/
+
+GLOBAL void com_build_UA_response (UBYTE ch_type, UBYTE sapi, UBYTE f_bit)
+{
+  TRACE_FUNCTION ("com_build_UA_response()");
+  com_build_frame (ch_type, UA_FRAME, sapi, MS2BS_RSP, 0, 0, f_bit, 0, 0, NULL, 0);
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_build_RR_response |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build an RR response.
+
+*/
+
+GLOBAL void com_build_RR_response (UBYTE ch_type,
+                                   UBYTE sapi, UBYTE nr, UBYTE f_bit)
+{
+  TRACE_FUNCTION ("com_build_RR_response()");
+  com_build_frame (ch_type, RR_FRAME, sapi, MS2BS_RSP, 0, nr, f_bit, 0, 0, NULL, 0);
+}
+
+#if 0
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_build_RR_command  |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build an RR command.
+
+*/
+
+GLOBAL void com_build_RR_command (T_DL_DATA_STORE * dl_data, UBYTE ch_type,
+                                  UBYTE sapi, UBYTE nr, UBYTE p_bit)
+{
+  TRACE_FUNCTION ("com_build_RR_command()");
+  com_build_frame (dl_data, ch_type, RR_FRAME, sapi, MS2BS_CMD, 0, nr, p_bit, 0, 0, NULL, 0);
+}
+#endif  /* 0 */
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_build_REJ_response|
++--------------------------------------------------------------------+
+
+  PURPOSE : Build an REJ response.
+
+*/
+
+GLOBAL void com_build_REJ_response (UBYTE ch_type,
+                                    UBYTE sapi, UBYTE nr, UBYTE f_bit)
+{
+  TRACE_FUNCTION ("com_build_REJ_response()");
+  com_build_frame (ch_type, REJ_FRAME, sapi, MS2BS_RSP, 0, nr, f_bit, 0, 0, NULL, 0);
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)           MODULE  : DL_COM                 |
+| STATE   : code                    ROUTINE : com_build_DISC_command |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build a DISC command.
+
+*/
+
+GLOBAL void com_build_DISC_command (UBYTE ch_type,
+                                    UBYTE sapi, UBYTE p_bit)
+{
+  TRACE_FUNCTION ("com_build_DISC_command()");
+  com_build_frame (ch_type, DISC_FRAME, sapi, MS2BS_CMD, 0, 0, p_bit, 0, 0, NULL, 0);
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)        MODULE  : DL_COM                    |
+| STATE   : code                 ROUTINE : com_build_SABM            |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build a SABM command with or without Layer 3 message.
+
+*/
+
+GLOBAL void com_build_SABM (UBYTE ch_type,
+                            UBYTE sapi, BOOL contention_resultion)
+{
+  GET_INSTANCE_DATA;
+  T_QUEUE *queue = &dl_data->dcch0_queue;
+  TRACE_FUNCTION ("com_build_SABM()");
+  TRACE_EVENT_WIN_P3 ("com_build_SABM %s SAPI=%u %s", CH_TYPE_NAME[ch_type], sapi,
+    (contention_resultion AND queue->switch_buffer) ? "+L3" : "");
+
+  if (contention_resultion AND queue->switch_buffer)
+  {
+    com_build_frame (ch_type, SABM_FRAME, sapi, MS2BS_CMD, 0, 0, 1,
+      (UBYTE)(queue->switch_buffer->sdu.l_buf >> 3), 0,
+      queue->switch_buffer->sdu.buf, (UBYTE)(queue->switch_buffer->sdu.o_buf >> 3));
+  }
+  else
+  {
+    com_build_frame (ch_type, SABM_FRAME, sapi, MS2BS_CMD, 0, 0, 1, 0, 0, NULL, 0);
+  }
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_build_DM_response |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build an DM response.
+
+*/
+
+GLOBAL void com_build_DM_response (UBYTE ch_type,
+                                   UBYTE sapi, UBYTE f_bit)
+{
+  TRACE_FUNCTION ("com_build_DM_response()");
+  com_build_frame (ch_type, DM_FRAME, sapi, MS2BS_RSP, 0, 0, f_bit, 0, 0, NULL, 0);
+}
+
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_build_I_command   |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build an I command.
+
+*/
+
+GLOBAL void com_build_I_command (UBYTE ch_type,
+                                 UBYTE sapi, UBYTE ns, UBYTE nr, UBYTE p_bit,UBYTE m_bit, T_QUEUE * queue)
+{
+  TRACE_FUNCTION ("com_build_I_command()");
+  com_build_frame (ch_type, I_FRAME, sapi, MS2BS_CMD, ns, nr, p_bit,
+    (UBYTE)(queue->transmit_buffer.l_buf >> 3), m_bit,
+    queue->transmit_buffer.buf, 0);
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)           MODULE  : DL_COM                 |
+| STATE   : code                    ROUTINE : com_build_UI_command   |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build an UI command.
+
+*/
+
+GLOBAL void com_build_UI_command (UBYTE ch_type,
+                                  UBYTE sapi, const T_FRAME * buffer)
+{
+  TRACE_FUNCTION ("com_build_UI_command()");
+  com_build_frame (ch_type, UI_FRAME, sapi, MS2BS_CMD, 0, 0, 0,
+    (UBYTE)(buffer->l_buf >> 3), 0, (UBYTE*)buffer->buf, (UBYTE)(buffer->o_buf >> 3));
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)           MODULE  : DL_COM                 |
+| STATE   : code                    ROUTINE : com_build_UI_Bter      |
++--------------------------------------------------------------------+
+
+  PURPOSE : Build an UI frame in Bter format.
+
+*/
+
+GLOBAL void com_build_UI_Bter (UBYTE ch_type)
+{
+  GET_INSTANCE_DATA;
+  unsigned off = dl_data->rr_short_pd_buffer.o_buf>>3;
+  unsigned len = dl_data->rr_short_pd_buffer.l_buf>>3;
+  unsigned foff, maxlen;
+
+  if (ch_type EQ L2_CHANNEL_SACCH)
+  {
+    maxlen = DL_N201_SACCH_Bter;
+    foff = 2;
+#ifndef  DL_2TO1
+    dl_data->l2_frame.A[0] = dl_data->l2_frame.A[1] = 0; /* place holder for L1 header */
+#else
+    dl_data->l2_frame.frame_array[0] = dl_data->l2_frame.frame_array[1] = 0; /* place holder for L1 header */
+#endif
+
+  }
+  else
+  {
+    foff = 0;
+    maxlen = DL_N201_DCCH_Bter;
+  }
+
+  if (len > maxlen)
+    len = maxlen;
+  /*
+   * LINT Warning 662: Possible creation of out-of-bounds pointer ...  and
+   * LINT Warning 669: Possible data overrun for function 'memset ...
+   * can be ignored, because of the right alignment between foff and maxlen.
+   */
+   /*lint -e662 -e669  Possible creation of out-of-bounds pointer or Possible data overrun*/
+#ifndef DL_2TO1
+  memcpy (&dl_data->l2_frame.A[foff], dl_data->rr_short_pd_buffer.buf+off, len);
+  memset (&dl_data->l2_frame.A[foff+len], 0x2b, maxlen-len);
+#else
+  memcpy (&dl_data->l2_frame.frame_array[foff], dl_data->rr_short_pd_buffer.buf+off, len);
+  memset (&dl_data->l2_frame.frame_array[foff+len], 0x2b, maxlen-len);
+#endif
+/* lint +e662 +e669 Possible creation of out-of-bounds pointer or Possible data overrun */
+/* mark message as handled */
+  dl_data->rr_short_pd_buffer.l_buf = 0;
+}
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_build_frame       |
++--------------------------------------------------------------------+
+
+  PURPOSE : Builds any frame.
+
+*/
+LOCAL void com_build_frame (UBYTE ch_type,
+                            UBYTE type, UBYTE sapi, UBYTE cr, UBYTE ns,
+                            UBYTE nr, UBYTE p_bit, UBYTE length, UBYTE m_bit,
+                            UBYTE* pInfoBuffer, UBYTE InfoOffset)
+{
+  GET_INSTANCE_DATA;
+  UBYTE offset;
+  UBYTE maxlength;
+#ifndef DL_2TO1
+  UBYTE *pOutFrame = dl_data->l2_frame.A;
+#else
+  UBYTE *pOutFrame = dl_data->l2_frame.frame_array;
+#endif /* DL_2TO1*/
+#define SPARE 0
+#define LPD   0
+#define EA    1
+#define EL    1
+
+  if (ch_type EQ L2_CHANNEL_SACCH)
+  {
+    offset = 2;
+    maxlength = DL_N201_SACCH_A_B;
+    pOutFrame[0] = pOutFrame[1] = 0; /* reset layer 1 header */
+  }
+  else
+  {
+    offset = 0;
+    maxlength = DL_N201_DCCH_A_B;
+  }
+
+  if (length > maxlength)
+  {
+    TRACE_EVENT_P1 ("Error: framelength to big %d", length);
+    length = maxlength; /* for safety's sake */
+  }
+
+  /*
+   * set header bytes (bit  8    7    6    5    4    3    2    1)
+   * address field          |    |    |    |         |    |    |
+   *                      Spare  --LPD-    ----SAPI---   C/R  EA
+   */
+  pOutFrame[offset] = (SPARE << 7) | (LPD << 5) | (sapi << 2) | (cr << 1) | EA;
+
+  /*
+   * control field          8    7    6    5    4    3    2    1
+   *  I format              ----N(R)---    P    ----N(S)---    0
+   *  S format              ----N(R)---   P/F   S    S    0    1
+   *  U format              U    U    U   P/F   U    U    1    1
+   */
+  if ((type & 0x01) EQ 0)
+    pOutFrame[offset+1] = (nr << 5) | (p_bit << 4) | (ns << 1);   /* I format */
+  else if ((type & 0x02) EQ 0)
+    pOutFrame[offset+1] = (nr << 5) | (p_bit << 4) | type;        /* S format */
+  else
+    pOutFrame[offset+1] = (p_bit << 4) | type;                    /* U format */
+
+  /*
+   * length field           8                        3    2    1
+   *                        -----length indicator-----    M   EL
+   */
+  pOutFrame[offset+2] = (length << 2) | (m_bit << 1) | EL;
+
+  /*
+   * LINT Warning 662: Possible creation of out-of-bounds pointer ... and
+   * LINT Warning 669: Possible data overrun for function 'memcpy ... and
+   * LINT Warning 671: Possibly passing to function 'memset ...
+   * can be ignored because the sum of offset, 3 plus maxlength (length) does
+   * never exceed the maximal size of pOutFrame[].
+   */
+  if (length && pInfoBuffer)
+  {/* copy info bits */
+    memcpy (&pOutFrame[offset+3], pInfoBuffer + (InfoOffset ? InfoOffset : 3), length);
+    offset += length;
+    maxlength -= length;
+  }
+
+  /* fill remain of the frame with 0x2b */
+  memset (&pOutFrame[offset+3], 0x2b, maxlength);
+
+#undef SPARE
+#undef LPD
+#undef EA
+#undef EL
+}/* endfunc com_build_frame */
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_data_ind          |
++--------------------------------------------------------------------+
+
+  PURPOSE : Indicates a downlinked message to RR. The queue which is
+            taken depend on the sapi value. In case of sapi=0 the function
+            checks the layer 3 message for a channel release additionally.
+            This is done to speed up the release procedure.
+
+*/
+GLOBAL void com_data_ind (UBYTE ch_type, UBYTE sapi, ULONG fn)
+{
+  GET_INSTANCE_DATA;
+  T_DL_DATA_IND *in_msg;
+
+#if defined(INVOKE_SIGNAL)
+    if (dl_data->interrupt_context)
+    {
+      sig_invoke_com_data_ind (ch_type, sapi, fn);
+      return;
+    }
+#endif  /* INVOKE_SIGNAL */
+
+  if (sapi EQ PS_SAPI_0)
+  {
+    in_msg = dl_data->dcch0_in_msg;
+
+    if (in_msg)
+    { /*
+       * Purpose: Check if message is channel release, then start release
+       * of connection. This will be done to speed up the DISC process.
+       */
+      /*lint -e415 (Warning -- access of out-of-bounds pointer) */
+      /*lint -e416 (Warning -- creation of out-of-bounds pointer) */
+      if ((in_msg->sdu.buf[3] EQ 0x06) AND   /* PD RR */
+        (in_msg->sdu.buf[4] EQ 0x0D))      /* MT channel release */
+      {
+      /*lint +e416 (Warning -- creation of out-of-bounds pointer) */
+      /*lint +e415 (Warning -- access of out-of-bounds pointer) */
+        /*
+         * Send immediately (on the next uplink opportunity) a DISC frame
+         * on DCCH.
+         * Disable dedicated mode -> restrain measurement reports
+         */
+        dl_data->dcch0_disc_request = TRUE;
+        DL_OFFLINE_TRACE(TRACE_DL_EVENT, C_DCCH0, ch_type, "CHANNEL REL received");
+#if !defined(LATE_LEAVING_DEDICATED)
+        com_leave_dedicated (ch_type);
+#endif  /* LATE_LEAVING_DEDICATED */
+      }
+    }
+  }
+  else
+  {
+    in_msg = dl_data->dcch3_in_msg;
+  }
+
+  if (in_msg)
+  {
+    in_msg->ch_type = ch_type;
+    in_msg->sapi    = sapi;
+    drr_dl_data_ind (sapi, fn);
+  }
+  else
+  {
+    DL_OFFLINE_TRACE (TRACE_DL_EVENT,
+      (sapi EQ PS_SAPI_0) ? C_DCCH0 : C_DCCH3, ch_type, "dcchx_in_msg=NULL");
+  }
+}
+
+#if !defined(NTRACE)
+#if defined(DL_TRACE_ENABLED) && defined(DL_IMMEDIATE_TRACE)
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_l2trace           |
++--------------------------------------------------------------------+
+
+  PURPOSE : Send L2 trace.
+
+*/
+
+GLOBAL void com_l2trace (UBYTE trace_type,
+                         UBYTE channel, UBYTE ch_type, T_TIME trace_time, UBYTE* data)
+{
+  GET_INSTANCE_DATA;
+  ULONG   trace_mask;
+
+#ifdef TI_PS_HCOMM_CHANGE
+  vsi_gettracemask(_hCommDL, _hCommDL, &trace_mask);
+#else
+  vsi_gettracemask(hCommDL, hCommDL, &trace_mask);
+#endif
+  if ((trace_mask & TC_USER1) EQ 0)
+    return;
+
+  if (trace_time EQ 0)
+    vsi_t_time (VSI_CALLER &trace_time);
+
+#if defined(INVOKE_SIGNAL)
+  if (dl_data->interrupt_context)
+  {
+    sig_invoke_com_l2trace (trace_type, channel, ch_type, trace_time, data);
+    return;
+  }
+#endif  /* INVOKE_SIGNAL */
+  dl_fast_trace(trace_type, channel, ch_type, trace_time, trace_mask, data);
+}
+#endif  /* DL_TRACE_ENABLED && DL_IMMEDIATE_TRACE */
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_l3trace           |
++--------------------------------------------------------------------+
+
+  PURPOSE : Send L3 trace.
+
+*/
+
+GLOBAL void com_l3trace (UBYTE type, UBYTE ch_type, UBYTE *frame)
+{
+  GET_INSTANCE_DATA;
+  ULONG trace_mask;
+
+#ifdef TI_PS_HCOMM_CHANGE
+  vsi_gettracemask(_hCommDL, _hCommDL, &trace_mask);
+#else  
+  vsi_gettracemask(hCommDL, hCommDL, &trace_mask);
+#endif
+  if ((trace_mask & TC_USER4) EQ 0)
+    return;
+
+#if defined(INVOKE_SIGNAL)
+  if (dl_data->interrupt_context)
+  {
+    sig_invoke_com_l3trace (type, ch_type, frame);
+    return;
+  }
+#endif  /* INVOKE_SIGNAL */
+
+  if (type EQ TRACE_UPLINK)
+  { /* uplink acknowledged */
+    T_DL_DATA_REQ *d = (T_DL_DATA_REQ *)frame;
+    com_print_l3trace (TRACE_UPLINK, ch_type, d->sapi, (UBYTE *)&d->sdu);
+  }
+  else if (type EQ TRACE_DOWNLINK)
+  { /* downlink */
+    T_DL_DATA_IND *d = (T_DL_DATA_IND *)frame;
+    com_print_l3trace (TRACE_DOWNLINK, ch_type, d->sapi, (UBYTE *)&d->sdu);
+  }
+  else if ((type EQ TRACE_UACK_UP) OR (type EQ TRACE_UACK_DN))
+  {
+    com_print_l3trace (type, ch_type, PS_SAPI_0, frame);
+  }
+}
+
+GLOBAL void com_print_l3trace (UBYTE type, UBYTE ch_type, UBYTE sapi, UBYTE *l3msg)
+{
+  char  description[40];
+
+  switch (type)
+  {
+    case TRACE_UPLINK:
+    case TRACE_DOWNLINK:
+      {
+        T_sdu *sdu = (T_sdu *)l3msg;
+        sprintf (description, "L3 %s ch=%u SAPI%u",
+          type EQ TRACE_UPLINK ? "UP" : "DN", ch_type, sapi);
+#ifdef TI_PS_HCOMM_CHANGE
+        TRACE_BINDUMP(_hCommDL, TC_USER4, description,
+                      sdu->buf+(sdu->o_buf>>3), (sdu->l_buf>>3));
+#else
+        TRACE_BINDUMP(hCommDL, TC_USER4, description,
+                      sdu->buf+(sdu->o_buf>>3), (sdu->l_buf>>3));
+#endif
+      }
+      break;
+    case TRACE_UACK_UP:
+    case TRACE_UACK_DN:
+      if (GET_BTER_FORMAT (&l3msg[0]) EQ SHORT_L2_HEADER_TYPE_1)
+      {
+        sprintf (description, "L3 %s ch=%u SAPI%u RR Short PD header",
+          type EQ TRACE_UACK_UP ? "UP" : "DN", ch_type, sapi);
+#ifdef TI_PS_HCOMM_CHANGE
+        TRACE_BINDUMP(_hCommDL, TC_USER4, description, l3msg, DL_N201_SACCH_Bter);
+#else
+        TRACE_BINDUMP(hCommDL, TC_USER4, description, l3msg, DL_N201_SACCH_Bter);
+#endif
+      }
+      else
+      {
+        sprintf (description, "L3 %s ch=%u SAPI%u",
+          type EQ TRACE_UACK_UP ? "UP" : "DN", ch_type, sapi);
+#ifdef TI_PS_HCOMM_CHANGE
+        TRACE_BINDUMP(_hCommDL, TC_USER4, description, l3msg, DL_N201_SACCH_A_B);
+#else
+        TRACE_BINDUMP(hCommDL, TC_USER4, description, l3msg, DL_N201_SACCH_A_B);
+#endif
+      }
+      break;
+  }
+}
+#endif  /* !NTRACE */
+
+/*
++--------------------------------------------------------------------+
+| PROJECT : GSM-PS (6147)            MODULE  : DL_COM                |
+| STATE   : code                     ROUTINE : com_init_data         |
++--------------------------------------------------------------------+
+
+  PURPOSE : Initializes the data for one instance.
+
+*/
+
+GLOBAL void com_init_data (void)
+{
+  GET_INSTANCE_DATA;
+  TRACE_FUNCTION ("com_init_data()");
+
+  memset (dl_data, 0, sizeof (T_DL_DATA_STORE));
+
+  dl_data->cch[C_DCCH0].T200_counter = 0;
+  dl_data->cch[C_DCCH3].T200_counter = 0;
+  dl_data->cch[C_SACCH0].T200_counter = 0;
+  dl_data->dcch0_in_msg = NULL;
+  dl_data->dcch3_in_msg = NULL;
+
+  dl_data->dcch0_disc_request = FALSE;
+  dl_data->dcch3_disc_request = FALSE;
+  dl_data->RR_dedicated = FALSE;
+  dl_data->fn = NOT_PRESENT_32BIT;
+
+#if defined(INVOKE_SIGNAL)
+  sig_init_signal_data ();
+#endif /* INVOKE_SIGNAL */
+}
+
+
+#if defined (DL_TRACE_ENABLED) || defined (FF_EM_MODE)
+/*
+*   Some of the functions originally designed for DL tracing are used as well for
+*   the engineering mode and therefore defined here.
+*/
+
+GLOBAL void com_semaphore_err (void)
+{
+#if defined(_SIMULATION_)
+  SYST_TRACE ("DL:error:semaphore");
+  TRACE_ASSERT (1);
+#else  /* _SIMULATION_ */
+static UCHAR out = 0;
+  if (!out)
+  {
+    out = 1;
+    SYST_TRACE ("DL:error:semaphore");
+    vsi_t_sleep(VSI_CALLER 10000);
+    TRACE_ASSERT (1);
+  }
+#endif  /* _SIMULATION_ */
+}
+
+GLOBAL int com_enter_critical_section (T_HANDLE sem)
+{
+  if (vsi_s_get (VSI_CALLER sem) NEQ VSI_OK)
+  {
+    com_semaphore_err();
+    return -1;
+  }
+  else
+  {
+    return 0;
+  }
+}/*endfunc com_enter_critical_section*/
+
+GLOBAL int com_leave_critical_section (T_HANDLE sem)
+{
+  if (vsi_s_release (VSI_CALLER sem) NEQ VSI_OK)
+  {
+    com_semaphore_err();
+    return -1;
+  }
+  else
+  {
+    return 0;
+  }
+}/* endfunc com_leave_critical_section */
+
+#if !defined(DL_IMMEDIATE_TRACE)
+GLOBAL int com_semaphore_state (T_HANDLE sem)
+{
+  USHORT  semCount;
+
+  if (vsi_s_status (VSI_CALLER sem, &semCount) NEQ VSI_OK)
+  {
+    com_semaphore_err ();
+    return -1;
+  }
+  if (semCount EQ 0)
+  {
+    SYST_TRACE ("DL:semCount == 0");
+    return 1;
+  }
+  else
+    return 0;
+}
+#endif /* !DL_IMMEDIATE_TRACE */
+#endif /* defined (DL_TRACE_ENABLED) || defined (FF_EM_MODE) */
+
+#endif  /* DL_COM_C */
+