process_a_packet.c

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#include "L1A_prototype.h"
#include "PGS_IO_L0.h"
#include "PGS_IO.h"
#include "PGS_SMF.h"
#include "PGS_MODIS_35005.h"
#include "PH_pkt_hdr.h"
 
static PGSt_SMF_status      next_return;
static PH_PACKET_HEADER_t   next_packet_header;   
static PGSt_IO_L0_Packet    next_pkt[PD_PKT_BUF_MAX];
static uint16           next_packet_cont[
                    PD_NUM_ELMTS_IN_DATA_FIELD_DAY_PKT
                    + PH_NUM_12BIT_WORDS_IN_HEADER + 1];
static PGSt_PC_Logical      next_packet_full = FALSE;
 
 
PGSt_SMF_status  process_a_packet (
    PGSt_IO_L0_VirtualDataSet   *L0_file,
    PGSt_IO_L0_Packet       *pkt,
    PH_PACKET_HEADER_t      *packet_header,
    uint16              *packet_cont
)
 
/*
!C************************************************************************
 
!Description:  This function is a driver that calls all the functions 
               necessary to validate a packet and unpack its contents.
 
!Input Parameters:
               None
 
!Output Parameters:
               PH_PACKET_HEADER_t  *packet_header  **  L0 data packet header **
               uint16              *packet_cont    **  Unpacked data packet  **
 
!Input/Output Parameters:
               PGSt_IO_L0_VirtualDataSet  *L0_file **  L0 virtual data set   **
 
Return Values: 
               MODIS_S_SUCCESS                    (PGS_MODIS_35005.h)
               MODIS_W_NO_MORE_PACKETS            (PGS_MODIS_35005.h)
               MODIS_F_PKT_PROCESS_FAILED         (PGS_MODIS-35005.h)
               MODIS_E_INV_VERSION                (PGS_MODIS_35005.h)
               MODIS_E_INV_TYPE                   (PGS_MODIS_35005.h)
               MODIS_E_INV_SEC_HDR_FLAG           (PGS_MODIS_35005.h)
               MODIS_E_INV_APID                   (PGS_MODIS_35005.h)
               MODIS_E_INV_APID_TEST              (PGS_MODIS_35005.h)
               MODIS_E_INV_PKT_SEQ_FLAG           (PGS_MODIS_35005.h)
               MODIS_E_FAILED_TIMECODE_CONV       (PGS_MODIS_35005.h)
               MODIS_E_INV_QL_FLAG                (PGS_MODIS_35005.h)
               MODIS_E_INV_PKT_TYPE               (PGS_MODIS_35005.h)
               MODIS_E_EARTH_FR_CNT_EXC_LIM       (PGS_MODIS_35005.h)
               MODIS_E_CAL_FR_CNT_EXC_LIM         (PGS_MODIS_35005.h)
               MODIS_E_CHECKSUM_NOT_VALID         (PGS_MODIS_35005.h)
 
Externally Defined:
               PGSt_SMF_status                 (PGS_SMF.h)
               PGSt_IO_L0_Packet               (PGS_IO.h)
               PGSt_IO_L0_VirtualDataSet       (PGS_IO.h)
               PH_PACKET_HEADER_t              (PH_pkt_hdr.h)
 
Called By:
               process_a_scan
               process_next_packet
 
Routines Called:
               read_a_packet
               unpack_packet_header   
               unpack_packet_contents
               check_checksum  
 
!Revision History:
$Log: process_a_packet.c,v $
Revision 5.1  2005/10/21 21:38:52  kuyper
No longer has return value indicating an invalid packet length.
 
Revision 4.1  2003/05/09 19:44:57  kuyper
Corrected process_a_packet() to copy over the packet and it's contents.
Change process_next_packet() to update an externally provided pointer, rather
  than copying the data it points at.
 
James Kuyper Jr. (kuyper@saicmodis.com)
 
Revision 4.0  2002/11/13 15:43:23  vlin
Updated according to process_next_packet.pdl revision 3.2
 
Revision 1.5  2001/11/20 17:01:41  seaton
Bit Flip Bug Fixes.
 
Revision 1.4  2001/04/13 18:09:20  seaton
Changed raw_mir_enc to type uint16 and fixed numerous prologs.
 
Revision 1.3  2000/10/03  15:27:01  seaton
Split Scan fix
 
Revision 2.2 2000/06/30
John Seaton GSC (seaton@ltpmail.gsfc.nasa.gov)
Code to fix split scan bug. DDTS MODx101733
 
!Team-unique Header:
    This software is developed by the MODIS Science Data Support Team 
    for the National Aeronautics and Space Administration, 
    Goddard Space Flight Center, under contract NAS5-32373.
 
References and Credits: None
 
Design Notes:
    The details for the packet data locations were taken from Santa Barbara
    Remote Sensing (SBRS) Contract Data Requirement List (CDRL)305, MODIS
    Engineering Telemetry Description, Tables T30-5A, T30-5B, T30-5C,
    T30-5D, and T30-5E.
!END*************************************************************************
*/
{
    PGSt_SMF_status returnStatus; /* SMF-style message returned by function */
 
    if (next_packet_full)
    {
    memcpy(pkt, next_pkt, sizeof(next_pkt));
    *packet_header = next_packet_header;
    memcpy(packet_cont, next_packet_cont, sizeof(next_packet_cont));
    next_packet_full = FALSE;  
    return next_return;
    }          
 
    if( (returnStatus = read_a_packet (L0_file, pkt)) == MODIS_S_SUCCESS &&
    (returnStatus = unpack_packet_header (pkt, packet_header))
    == MODIS_S_SUCCESS )
    {
    unpack_packet_contents (pkt, packet_header, packet_cont);
    returnStatus = check_checksum (*packet_header, packet_cont);
    }
 
    return returnStatus;
}
 
/*===========================================================================*/
 
PGSt_SMF_status  process_next_packet(
    PGSt_IO_L0_VirtualDataSet   *L0_file,
    PH_PACKET_HEADER_t      **packet_header
)
 
/*****************************************************************************
!C
 
!Description:  'Peeks' at next packet available in the L0_file while
                leaving it in line to be read by process_a_packet.
 
!Input Parameters:
       PGSt_IO_L0_VirtualDataSet  L0_file         L0 virtual data set
 
!Output Parameters:
       PH_PACKET_HEADER_t         packet_header   L0 data packet header
 
Return Values:
               MODIS_E_CAL_FR_CNT_EXC_LIM
               MODIS_E_CHECKSUM_NOT_VALID
               MODIS_E_EARTH_FR_CNT_EXC_LIM
               MODIS_E_FAILED_TIMECODE_CONV
               MODIS_E_INV_APID
               MODIS_E_INV_APID_TEST
               MODIS_E_INV_PKT_SEQ_FLAG
               MODIS_E_INV_PKT_TYPE
               MODIS_E_INV_QL_FLAG
               MODIS_E_INV_SEC_HDR_FLAG
               MODIS_E_INV_TYPE
               MODIS_F_PKT_PROCESS_FAILED
               MODIS_E_INV_VERSION
               MODIS_S_SUCCESS
               MODIS_W_CANT_PKT_PEEK
               MODIS_W_NO_MORE_PACKETS
 
Externally Defined:
               MODIS_E_CAL_FR_CNT_EXC_LIM         (PGS_MODIS_35005.h)
               MODIS_E_CHECKSUM_NOT_VALID         (PGS_MODIS_35005.h)
               MODIS_E_EARTH_FR_CNT_EXC_LIM       (PGS_MODIS_35005.h)
               MODIS_E_FAILED_TIMECODE_CONV       (PGS_MODIS_35005.h)
               MODIS_E_INV_APID                   (PGS_MODIS_35005.h)
               MODIS_E_INV_APID_TEST              (PGS_MODIS_35005.h)
               MODIS_E_INV_PKT_SEQ_FLAG           (PGS_MODIS_35005.h)
               MODIS_E_INV_PKT_TYPE               (PGS_MODIS_35005.h)
               MODIS_E_INV_QL_FLAG                (PGS_MODIS_35005.h)
               MODIS_E_INV_SEC_HDR_FLAG           (PGS_MODIS_35005.h)
               MODIS_E_INV_TYPE                   (PGS_MODIS_35005.h)
               MODIS_E_INV_VERSION                (PGS_MODIS_35005.h)
               MODIS_S_SUCCESS                    (PGS_MODIS_35005.h)
               MODIS_F_PKT_PROCESS_FAILED         (PGS_MODIS_35005.h)
               MODIS_W_CANT_PKT_PEEK              (PGS_MODIS_35005.h)
               MODIS_W_NO_MORE_PACKETS            (PGS_MODIS_35005.h)
               PD_NUM_ELMTS_IN_DATA_FIELD_DAY_PKT (PD_pkt_data.h)
               PGSt_IO_L0_Packet                  (PGS_IO.h)
               PGSt_IO_L0_VirtualDataSet          (PGS_IO.h)
               PGSt_PC_Logical                    (PGS_PC.h)
               PGSt_SMF_status                    (PGS_SMF.h)
               PH_PACKET_HEADER_t                 (PH_pkt_hdr.h)
               PH_NUM_12BIT_WORDS_IN_HEADER       (PH_pkt_hder.h)
               TRUE                               (hdf.h)
               uint8                              (hdfi.h)
 
               File scope variables shared only with process_a_packet:
               PGSt_SMF_status          next_return
               PGSt_IO_L0_Packet        next_pkt[PD_PKT_BUF_MAX]
               PH_PACKET_HEADER_t       next_packet_header
               uint16                   next_packet_cont[PD_NUM_ELMTS_IN_DATA_FIELD_DAY_PKT
                                        + PH_NUM_12BIT_WORDS_IN_HEADER + 1]
               PGSt_PC_Logical          next_packet_full initialized to FALSE 
 
Called By:
               packet_of_scan
                
Routines Called:
               process_a_packet
               
!Revision History:
   Please see prologue in "process_a_packet()"
 
!Team-unique Header:
 
      This software is developed by the MODIS Science Data Support Team 
      for the National Aeronautics and Space Administration, 
      Goddard Space Flight Center, under contract NAS5-32373.
                                                               
References and Credits:   None
 
Design Notes:
               Issue: Globals modified by subroutines of process_a_packet
                (like incrementing global packet counters) could cause
                unintended side-effects from calling this routine.
               
!END
******************************************************************************/
 
{
    if (next_packet_full)
    return MODIS_E_CANT_PKT_PEEK;
    else
    {       
    next_return = process_a_packet(L0_file, next_pkt, &next_packet_header,
        next_packet_cont);
    *packet_header = &next_packet_header;
    next_packet_full = TRUE;
 
    return next_return;
    }
}