NAME

       ms_find_reclen - Determine SEED record data length

SYNOPSIS

       #include <libmseed.h>

       int  ms_find_reclen ( const char *recbuf, int recbuflen,
                                   FILE *fileptr );

DESCRIPTION

       ms_find_reclen  verifies  that  the specified recbuf buffer contains a SEED data record by
       looking for data record signatures in the fixed section data  header  and  determines  the
       data  record  length by 1) searching the buffer up to recbuflen bytes for a Blockette 1000
       and, failing that, 2) if fileptr is not NULL reading the next 48 bytes from the  file  and
       looking  for  a data record signature (with detection of the next data record implying the
       length of the current record).  If data is read from fileptr the read position is returned
       to it's position prior to this function call.

       The  MS_ISVALIDHEADER  macro  is used to verify that the buffer contains a valid SEED data
       record.  When searching for the next record header to determine record length one  of  the
       macros  MS_ISVALIDHEADER  or  MS_ISVALIDBLANK  must  test  positively  for  a record to be
       detected.  Blank/noise records are records with a valid SEED sequence number  followed  by
       ASCII space characters to the end of the record.

       ms_find_reclen  will  return 0 when it detects that the buffer contains a SEED data record
       but cannot determine the record length.  This happens when no Blockette 1000 is not  found
       within  recbuflen  bytes  and,  assuming  a valid fileptr is supplied, no record header is
       detected in the next 48 bytes of the file.  The idea is to then read more  data  from  the
       file  (i.e.  the next larger, valid record length) and call ms_find_reclen again and so on
       until the record length can be determined.

RETURN VALUES

       ms_find_reclen returns the length of the Mini-SEED record in bytes or 0 if a  data  record
       was  detected  but  the  length  could  not  be  determined  or -1 when no data record was
       detected.

SEE ALSO

       ms_readmsr(3), ms_readtraces(3) and msr_unpack(3).

AUTHOR

       Chad Trabant
       IRIS Data Management Center