From 67516a90849f8a98c57e8a3bf215f67dbb596e89 Mon Sep 17 00:00:00 2001
From: Oskari Alaranta <oskari.alaranta@bananymous.com>
Date: Mon, 20 Oct 2025 22:21:28 +0300
Subject: [PATCH] Cleanup format string placement code

---
 main.cpp | 59 ++++++++++++++++++++++++++++----------------------------
 1 file changed, 29 insertions(+), 30 deletions(-)

diff --git a/main.cpp b/main.cpp
index 92bf29c..58dc1df 100644
--- a/main.cpp
+++ b/main.cpp
@@ -773,37 +773,36 @@ QRCode generate_qr_code(std::string_view data, ErrorCorrection ec)
 		const uint16_t format_data = (ec_to_val[static_cast<size_t>(qr_info.error_correction)] << 13) | (pattern << 10);
 		const uint16_t format_string = (format_data | mod2_remainder(format_data, 0b10100110111, 10)) ^ 0b101010000010010;
 
-		qr_code.set(0, 8, (format_string >> 14) & 1);
-		qr_code.set(1, 8, (format_string >> 13) & 1);
-		qr_code.set(2, 8, (format_string >> 12) & 1);
-		qr_code.set(3, 8, (format_string >> 11) & 1);
-		qr_code.set(4, 8, (format_string >> 10) & 1);
-		qr_code.set(5, 8, (format_string >>  9) & 1);
-		qr_code.set(7, 8, (format_string >>  8) & 1);
-		qr_code.set(8, 8, (format_string >>  7) & 1);
-		qr_code.set(8, 7, (format_string >>  6) & 1);
-		qr_code.set(8, 5, (format_string >>  5) & 1);
-		qr_code.set(8, 4, (format_string >>  4) & 1);
-		qr_code.set(8, 3, (format_string >>  3) & 1);
-		qr_code.set(8, 2, (format_string >>  2) & 1);
-		qr_code.set(8, 1, (format_string >>  1) & 1);
-		qr_code.set(8, 0, (format_string >>  0) & 1);
+		constexpr int8_t format_location[][2][2] {
+			{ { 8, 0 }, { -1,  8 } },
+			{ { 8, 1 }, { -2,  8 } },
+			{ { 8, 2 }, { -3,  8 } },
+			{ { 8, 3 }, { -4,  8 } },
+			{ { 8, 4 }, { -5,  8 } },
+			{ { 8, 5 }, { -6,  8 } },
+			{ { 8, 7 }, { -7,  8 } },
+			{ { 8, 8 }, { -8,  8 } },
+			{ { 7, 8 }, {  8, -7 } },
+			{ { 5, 8 }, {  8, -6 } },
+			{ { 4, 8 }, {  8, -5 } },
+			{ { 3, 8 }, {  8, -4 } },
+			{ { 2, 8 }, {  8, -3 } },
+			{ { 1, 8 }, {  8, -2 } },
+			{ { 0, 8 }, {  8, -1 } },
+		};
 
-		qr_code.set(8, size - 1, (format_string >> 14) & 1);
-		qr_code.set(8, size - 2, (format_string >> 13) & 1);
-		qr_code.set(8, size - 3, (format_string >> 12) & 1);
-		qr_code.set(8, size - 4, (format_string >> 11) & 1);
-		qr_code.set(8, size - 5, (format_string >> 10) & 1);
-		qr_code.set(8, size - 6, (format_string >>  9) & 1);
-		qr_code.set(8, size - 7, (format_string >>  8) & 1);
-		qr_code.set(size - 8, 8, (format_string >>  7) & 1);
-		qr_code.set(size - 7, 8, (format_string >>  6) & 1);
-		qr_code.set(size - 6, 8, (format_string >>  5) & 1);
-		qr_code.set(size - 5, 8, (format_string >>  4) & 1);
-		qr_code.set(size - 4, 8, (format_string >>  3) & 1);
-		qr_code.set(size - 3, 8, (format_string >>  2) & 1);
-		qr_code.set(size - 2, 8, (format_string >>  1) & 1);
-		qr_code.set(size - 1, 8, (format_string >>  0) & 1);
+		for (size_t bit = 0; bit < 15; bit++)
+		{
+			for (size_t i = 0; i < 2; i++)
+			{
+				const auto [x, y] = format_location[bit][i];
+				qr_code.set(
+					x < 0 ? size + x : x,
+					y < 0 ? size + y : y,
+					(format_string >> bit) & 1
+				);
+			}
+		}
 	}
 
 	// version string