A demo inventory application for the Psion Workabout MX: scan UPC barcodes, and (Phase 2) keep stock counts in a database file, adding stock or consuming it by scanning.

Written in PLIB C, built with the TopSpeed compiler (tsc /m scan).

Phases

Phase 1 (this commit): scan and validate. Reads barcodes from the scanner and prints each one, flagging whether it is a valid UPC-A. Modules: upc (validation), bcode (scanner input), scan (the demo).
Phase 2 (next): inventory database. A DBF file keyed on UPC holding a quantity and a name. Scan to add stock (increment, or create on first sight), scan to consume by a quantity unit. Built on the SIBO Dbf* API.

Build

tsc /m scan

Produces scan.img. scan.pr compiles upc.c, bcode.c and scan.c and links them.

How the scanner is read

On the Workabout the barcode module decodes the label in hardware and sends the result as an RS232 stream, so there is no special barcode driver call: the app opens the serial port and reads it. The scanner is on the top internal slot, which is port D, so the device is TTY:D (bcode.c).

The scan loop is blocking: it reads the scanner and prints each barcode; you exit via the System screen. (An asynchronous scan-or-Esc loop was tried but panicked the Window Server: on SIBO the keyboard is event-driven through the window server, not a raw CON: byte read, and a proper async loop needs the Window Server event API, whose reference manual is not in this repo's docs/.)

This Phase 1 build also prints the byte length of each decoded barcode, so the exact format the scanner emits for a UPC can be confirmed before Phase 2 uses it as a database key.

Things to confirm on the device

Because this cannot be compiled or run off-device, these points are written to the SDK docs but may need adjusting once you build and test:

Serial line settings. bcodeOpen opens TTY:D with the default mode. If the scanner needs a specific baud/parity/framing, configure the channel with p_iow(chan, P_FSET, &config) (E_CONFIG, p_config.h) after opening.
Terminator. BCODE_TERM in bcode.h is set to CR (0x0D), the common case. Change it if your scanner suffixes LF or something else.
Raw scan format. The build prints len=NN [text] per scan. Confirm whether a UPC arrives as exactly 12 digits or with extra characters (a leading zero / EAN-13, or a symbology prefix); Phase 2 normalises to the database key based on this.