feat(inventory): WL2:D async read (p_ioc + trigger + p_iowait)

code/inventory/scan.c

@@ -1,12 +1,11 @@
 /*
- * scan.c - Phase 1: WL2:D scanner, trigger + read loop (reverse-engineered).
+ * scan.c - Phase 1: WL2:D scanner, asynchronous read (reverse-engineered).
  *
- * Confirmed from the previous build: opening WL2:D then issuing control ops 6
- * and 7 triggers a scan (laser fires, green good-read LED). What was missing was
- * the read: a bare p_iow(chan, P_FREAD, buf) passes no length. This uses p_read
- * (which passes &len) to collect the decoded result, and re-triggers (ops 6/7)
- * each iteration so successive scans work without relying on the scan key.
- * Decoded output is CR/LF-terminated (default Symbol2 postamble).
+ * Confirmed: opening WL2:D and issuing control ops 6/7 triggers a scan (laser
+ * fires, green LED). Neither synchronous read form returned data, and SCANAPP
+ * in the ROM uses an async pattern (post read -> P_FREAD -> P_FCANCEL). So this
+ * posts an asynchronous read (p_ioc), triggers the scan (ops 6/7), then waits
+ * for completion (p_iowait). Decoded output is CR/LF-terminated.
  */
 #include <plib.h>
 
@@ -17,7 +16,9 @@ GLDEF_C INT main(VOID)
 {
     VOID *chan;
     UBYTE buf[256];
-    INT   err, n, i;
+    WORD  stat;
+    UWORD len;
+    INT   err, i;
 
     err = p_open(&chan, "WL2:D", (UINT)-1);
     p_printf("open WL2:D: %d\n", err);
@@ -27,23 +28,32 @@ GLDEF_C INT main(VOID)
         return 1;
     }
 
-    p_printf("Present a barcode under the laser. Reads:\n\n");
+    p_printf("Present a barcode under the laser. Async reads:\n\n");
 
     for (;;) {
-        p_iow(chan, WL2_TRIG1);            /* trigger a scan */
+        len  = sizeof(buf);
+        stat = E_FILE_PENDING;
+        p_ioc(chan, P_FREAD, &stat, buf, &len);   /* post async read */
+
+        p_iow(chan, WL2_TRIG1);                    /* trigger the scan */
         p_iow(chan, WL2_TRIG2);
-        n = p_read(chan, buf, sizeof(buf));   /* collect decoded result (with len) */
-        if (n < 0) {
-            p_printf("read %d\n", n);
+
+        p_iowait();                                /* wait for a completion */
+
+        if (stat == E_FILE_PENDING) {              /* our read didn't finish */
+            p_iow(chan, P_FCANCEL);
+            p_waitstat(&stat);
             continue;
         }
-        if (n == 0)
+        if (stat < 0) {
+            p_printf("stat %d\n", stat);
             continue;
-        p_printf("n=%d:", n);
-        for (i = 0; i < n && i < 40; i++)
+        }
+        p_printf("len=%d:", len);
+        for (i = 0; i < 40 && i < 256; i++)
             p_printf(" %d", buf[i]);
         p_printf("  \"");
-        for (i = 0; i < n && i < 40; i++)
+        for (i = 0; i < 40 && i < 256; i++)
             p_putch(buf[i] >= ' ' ? buf[i] : '.');
         p_printf("\"\n");
     }