95 lines
3.1 KiB
C
95 lines
3.1 KiB
C
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/*
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* scan.c - Phase 1 inventory demo: scan UPC barcodes and display them.
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*
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* Opens the barcode serial channel (TTY:D) and its own console/keyboard
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* channel (CON:), then waits on both at once: a completed scan is validated
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* as a UPC-A and printed; pressing Esc quits.
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*
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* Asynchronous two-channel wait (PLIB pattern): each request is started with
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* p_ioc, which sets a status word to E_FILE_PENDING until the request
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* completes. p_iowait blocks until some request finishes; we then check each
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* status word, cancel the other outstanding request, and loop. Every started
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* request is matched by exactly one completion (real or cancelled) so the I/O
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* semaphore stays balanced. See "Asynchronous I/O" in the PLIB Reference.
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*/
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#include <plib.h>
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#include "bcode.h"
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#include "upc.h"
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#define KEY_ESC 27
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/*
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* If a request on chan is still pending, cancel it and reap the resulting
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* completion, so the started p_ioc is balanced by a wait.
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*/
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LOCAL_C VOID cancelPending(VOID *chan, WORD *pStat)
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{
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if (*pStat == E_FILE_PENDING) {
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p_iow(chan, P_FCANCEL);
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p_waitstat(pStat);
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}
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}
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GLDEF_C INT main(VOID)
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{
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VOID *bchan; /* barcode serial channel */
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VOID *kchan; /* keyboard console channel */
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WORD bStat, kStat; /* async status words */
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UBYTE bRaw[BCODE_MAXLEN]; /* raw bytes from one serial read */
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UBYTE kRaw[1]; /* one keystroke */
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TEXT line[BCODE_MAXLEN]; /* barcode assembled across reads */
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INT lineLen = 0;
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UWORD bLen, kLen;
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INT err;
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INT quit = 0;
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if ((err = bcodeOpen(&bchan)) < 0) {
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p_printf("Cannot open barcode port TTY:D (err %d)\n", err);
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return 1;
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}
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if ((err = p_open(&kchan, "CON:", (UINT)-1)) < 0) {
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p_printf("Cannot open console (err %d)\n", err);
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bcodeClose(bchan);
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return 1;
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}
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p_printf("Inventory scan demo\n");
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p_printf("Scan a UPC, or press Esc to quit.\n\n");
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while (quit == 0) {
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/* Start one asynchronous read on each channel. */
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bLen = sizeof(bRaw);
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p_ioc(bchan, P_FREAD, &bStat, bRaw, &bLen);
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kLen = sizeof(kRaw);
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p_ioc(kchan, P_FREAD, &kStat, kRaw, &kLen);
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p_iowait();
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/* Keypress? Cancel the scan read and check for Esc. */
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if (kStat != E_FILE_PENDING) {
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cancelPending(bchan, &bStat);
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if (kStat >= 0 && kRaw[0] == KEY_ESC)
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quit = 1;
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continue;
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}
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/* Scanner delivered bytes. Cancel the keypress read and assemble. */
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if (bStat != E_FILE_PENDING) {
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cancelPending(kchan, &kStat);
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if (bStat >= 0 && bLen > 0) {
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if (bcodeAssemble(bRaw, (INT)bLen, line, &lineLen, BCODE_MAXLEN)) {
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if (upcIsValid(line))
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p_printf("OK %s\n", line);
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else
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p_printf("BAD %s (not a valid UPC-A)\n", line);
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}
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}
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}
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}
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p_printf("\nDone.\n");
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p_close(kchan);
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bcodeClose(bchan);
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return 0;
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}
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