From b79b1fa1751db6a55a9f298be4453e93a3cfb28e Mon Sep 17 00:00:00 2001
From: lyrathorpe <iam@emmathe.dev>
Date: Mon, 6 Jul 2026 20:21:03 +0100
Subject: [PATCH] diag(inventory): software-trigger scan via Esc-y1J/Esc-y1K
 over TTY:D

---
 code/inventory/scan.c | 36 ++++++++++++++++++++++--------------
 1 file changed, 22 insertions(+), 14 deletions(-)

diff --git a/code/inventory/scan.c b/code/inventory/scan.c
index ee32c57..d80683d 100644
--- a/code/inventory/scan.c
+++ b/code/inventory/scan.c
@@ -1,17 +1,15 @@
 /*
- * scan.c - Phase 1 barcode diagnostic: minimal TTY:D barcode-driver read.
+ * scan.c - Phase 1 barcode diagnostic: software-triggered scan over TTY:D.
  *
- * TTY:D is the top-slot bar code interface (I/O Devices Reference, HC
- * Intelligent Bar Code Reader chapter). Opening it powers the interface and
- * the scanner; by default the scanner is enabled and in auto-read mode, and it
- * transmits each decoded label as ASCII text terminated by a carriage return.
+ * TTY:D is the top-slot bar code interface. It did not auto-transmit on a scan,
+ * so this build uses the documented escape-sequence trigger (I/O Devices
+ * Reference, HC Intelligent Bar Code Reader chapter):
+ *   <Esc>-y1J  enable single-read mode
+ *   <Esc>-y1K  "read next scan" - arms the reader for one label
+ * After each decoded label (terminated by CR) it re-arms with another K.
+ * Every received byte is streamed as a decimal value.
  *
- * Earlier attempts failed for self-inflicted reasons: a P_FSET forced 9600/8/1
- * (wrong if the scanner uses another rate, which garbles the data) and a
- * 64-byte read blocked forever with no terminator set. This build does NEITHER:
- * it opens TTY:D, changes nothing, and reads ONE byte at a time, streaming each
- * value. Scan during the brief active window after launch (re-trigger with the
- * scan key if needed).
+ * <Esc>=0x1b, '-'=0x2d, 'y'=0x79. Escape sequences carry no embedded spaces.
  */
 #include <plib.h>
 
@@ -21,6 +19,9 @@ GLDEF_C INT main(VOID)
     UBYTE b;
     INT   err, n, c;
 
+    static TEXT cmdJ[5] = { 0x1b, '-', 'y', '1', 'J' };  /* single-read mode on */
+    static TEXT cmdK[5] = { 0x1b, '-', 'y', '1', 'K' };  /* trigger one scan    */
+
     err = p_open(&chan, "TTY:D", (UINT)-1);
     p_printf("open TTY:D: %d\n", err);
     if (err < 0) {
@@ -29,10 +30,15 @@ GLDEF_C INT main(VOID)
         return 1;
     }
 
-    p_printf("Scan now. Streaming bytes:\n\n");
+    err = p_write(chan, cmdJ, 5);
+    p_printf("single-read mode (Esc-y1J): %d\n", err);
+    err = p_write(chan, cmdK, 5);
+    p_printf("trigger (Esc-y1K): %d\n", err);
+
+    p_printf("\nPoint at a barcode. Streaming bytes:\n\n");
 
     for (;;) {
-        n = p_read(chan, &b, 1);   /* one byte; no reconfiguration at all */
+        n = p_read(chan, &b, 1);
         if (n < 0) {
             p_printf("<e%d>", n);
             continue;
@@ -41,7 +47,9 @@ GLDEF_C INT main(VOID)
             continue;
         c = b;
         p_printf(" %d", c);
-        if (c == 13 || c == 10)
+        if (c == 13 || c == 10) {
             p_printf(" <EOL>\n");
+            p_write(chan, cmdK, 5);   /* re-arm for the next scan */
+        }
     }
 }