fix: Han Xin correct separator + function info regions from Zint

- 8-module separator bands around all 4 finders (was 1-module)
- 9-module function information reserved regions
- Update README: 18 verified formats, MicroPDF417 now reference-matched

Match improved 75% → 76%. Finders remain 100%.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: productdevbook

README.md

@@ -13,9 +13,9 @@
 </p>
 
 > [!IMPORTANT]
-> **Scan-verified formats (16):** QR Code, Data Matrix, PDF417, Aztec, Micro QR, rMQR, MaxiCode, Code 128, EAN-13, EAN-8, UPC-A, Code 39, Code 93, ITF, Codabar, GS1-128 — all verified with round-trip encode/decode tests using zxing-wasm, rxing (Rust), and gozxing (Go).
+> **Verified formats (18):** QR Code, Data Matrix, PDF417, Aztec, Micro QR, rMQR, MaxiCode, MicroPDF417, Code 128, EAN-13, EAN-8, UPC-A, Code 39, Code 93, ITF, Codabar, GS1-128, Codablock F — verified with round-trip scan tests (zxing-wasm, rxing, gozxing) and/or 100% bit-match against Zint/bwip-js reference.
 >
-> **Experimental formats:** MicroPDF417, DotCode, Han Xin, JAB Code — no open-source barcode decoder exists for these formats (even bwip-js/Zint reference images cannot be scanned). Encoders produce structurally valid output. PRs welcome.
+> **Experimental formats:** DotCode, Han Xin, JAB Code — no open-source decoder exists for these formats. Encoders produce structurally valid output (Han Xin 75% reference match, finders 100%). PRs welcome.
 >
 > **Contributions welcome!** If you find a scanning issue or want to improve an encoder, please [open an issue](https://github.com/productdevbook/etiket/issues) or submit a PR. See [Contributing](#contributing) below.
 
@@ -451,12 +451,9 @@ Contributions are welcome! Here are some areas where help is especially apprecia
 
 **Encoder improvements needed:**
 
-- **rMQR** — Format info encoding and alignment pattern placement need work
-- **MicroPDF417** — RAP (Row Address Pattern) index calculations need verification against ISO/IEC 24728
-- **MaxiCode** — Hexagonal module placement algorithm needs correction per ISO/IEC 16023
-- **DotCode** — Dot placement and mask pattern per AIM ISS DotCode 4.0
-- **Han Xin** — GB 18030 Chinese character encoding mode
-- **Code 16K** — Row-specific start patterns per AIM BC7-2000
+- **DotCode** — Symbol size selection tables and mask pattern per AIM ISS DotCode 4.0
+- **Han Xin** — Separator bands, data placement, and GB 18030 Chinese character encoding (75% reference match, finders 100%)
+- **JAB Code** — Full LDPC error correction per ISO/IEC 23634
 
 **Other contributions:**
 

src/encoders/hanxin.ts

@@ -329,21 +329,36 @@ export function encodeHanXin(text: string, options: HanXinOptions = {}): boolean
   placeFinderHX(matrix, size - 7, 0, FINDER_BL, size);
   placeFinderHX(matrix, size - 7, size - 7, FINDER_BR, size);
 
-  // Han Xin has NO timing patterns — only separator bands around finders
-  // 1-module white separator around each 7x7 finder
-  for (let i = -1; i <= 7; i++) {
+  // Separator: 8-module white border around each finder (row/col 7 and symmetric)
+  for (let i = 0; i < 8; i++) {
     // Top-left separator
-    setSafeNull(matrix, 7, i, size);
-    setSafeNull(matrix, i, 7, size);
+    matrix[7]![i] = false;
+    matrix[i]![7] = false;
     // Top-right separator
-    setSafeNull(matrix, 7, size - 8 + i, size);
-    setSafeNull(matrix, i, size - 8, size);
+    matrix[7]![size - 1 - i] = false;
+    matrix[i]![size - 8] = false;
     // Bottom-left separator
-    setSafeNull(matrix, size - 8, i, size);
-    setSafeNull(matrix, size - 8 + i, 7, size);
+    matrix[size - 8]![i] = false;
+    matrix[size - 1 - i]![7] = false;
     // Bottom-right separator
-    setSafeNull(matrix, size - 8, size - 8 + i, size);
-    setSafeNull(matrix, size - 8 + i, size - 8, size);
+    matrix[size - 8]![size - 1 - i] = false;
+    matrix[size - 1 - i]![size - 8] = false;
+  }
+
+  // Function information region: 9-module reserved area (row/col 8 and symmetric)
+  for (let i = 0; i < 9; i++) {
+    // Top-left
+    if (matrix[8]![i] === null) matrix[8]![i] = false;
+    if (matrix[i]![8] === null) matrix[i]![8] = false;
+    // Top-right
+    if (matrix[8]![size - 1 - i] === null) matrix[8]![size - 1 - i] = false;
+    if (matrix[i]![size - 9] === null) matrix[i]![size - 9] = false;
+    // Bottom-left
+    if (matrix[size - 9]![i] === null) matrix[size - 9]![i] = false;
+    if (matrix[size - 1 - i]![8] === null) matrix[size - 1 - i]![8] = false;
+    // Bottom-right
+    if (matrix[size - 9]![size - 1 - i] === null) matrix[size - 9]![size - 1 - i] = false;
+    if (matrix[size - 1 - i]![size - 9] === null) matrix[size - 1 - i]![size - 9] = false;
   }
 
   // Place data bits into available modules