xxds is a C program that reads Variable Block (VB) format files and displays them in hexadecimal format with EBCDIC character representation.

xxds reads VB format files from standard input and prints them in a hex dump format similar to xxd or hexdump, but specifically designed for EBCDIC-encoded Variable Block files. The program processes records by reading the RDW containing a 2-byte big-endian length field, followed by the record data.

To build the program:

make

This will compile xxds.c and create the xxds executable.

To install the program system-wide:

sudo make install

This will copy the executable to /usr/local/bin/.

Read from a file:

./xxds < input_file.vb

Or pipe input:

cat input_file.vb | ./xxds

For each record, the program prints:

1. Record Header: Record: nnnn Length: nnnn Offset: xxxxxxxx

   • Record number (starting from 1)
   • Record length in bytes
   • File offset in hexadecimal

2. Hex Dump: Each 16-byte chunk is displayed as:

   oooo:  xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx  cccccccccccccccc
   

   • oooo: Offset within the record (4 hex digits)
   • xxxxxxxx: Four groups of 4 bytes in hexadecimal
   • cccccccccccccccc: EBCDIC character representation (unprintable chars shown as dots)

3. End of File Summary: Printed after the last record:

   End of file: n record[s], nnnn byte[s] (xxxxxxxx)
   

   • n: Total number of records read
   • nnnn: Total number of bytes read
   • xxxxxxxx: File size in hexadecimal

Record: 1  Length: 88  Offset: 00000000
0000:  00580000 00800050  D7C1E4E3 E2E4D4F0  .......&PAUTSUM0
0010:  00000000 00000000  00000000 00000000  ................
0020:  00000000 00000000  00000000 01010072  ................
0030:  D7C1E4E3 C4E3D3F1  00000000 00000000  PAUTDTL1........
0040:  00000000 00000000  00000000 00000000  ................
0050:  00000000 020280CE                    ........
End of file: 1 record, 88 bytes (00000058)

• Reads Variable Block format files from stdin
• Displays records with hex dump and EBCDIC character representation
• Handles incomplete records gracefully
• Tracks record count and total byte count
• Uses EBCDIC Code Page 037 for character conversion
• Supports records up to 32K in size

VB format records consist of:

• 4 bytes: RDW consisting of:
  • a big-endian 16-bit unsigned integer specifying the total record length (including the RDW itself)
  • 2 flag bytes (ignored by this program)
• Remaining bytes: Record data (length - 4 bytes)

If a record is incomplete (file ends before the expected end of the record), the program will:

• Display the partial record data
• Print "Last record incomplete"
• Continue with the end-of-file summary

This program is licensed under the MIT License.