<?php

echo "=== Visual Format Information Comparison ===\n\n";

echo "BEFORE FIX (Double Swapping):\n";
echo "─────────────────────────────────────────────\n";
echo "Bit Index Mapping: [0,1,2,3,4,5,6,7,8,10,9,11,13,12,14]\n";
echo "                                      ^swap^   ^swap^\n\n";

echo "Column Order:      [0,1,2,3,4,5,7,8,20,19,18,17,16,15,14]\n";
echo "                                      ← right-to-left →\n\n";

echo "Result: DOUBLE SWAP = WRONG\n";
echo "  Horizontal: 101111001111010\n";
echo "  Vertical:   101111001111100\n";
echo "              ─────────────^^ MISMATCH!\n\n\n";

echo "AFTER FIX (Sequential Placement):\n";
echo "─────────────────────────────────────────────\n";
echo "Bit Index:         [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14]\n";
echo "                    Sequential - NO manual swapping\n\n";

echo "Column Order:      [0,1,2,3,4,5,7,8,20,19,18,17,16,15,14]\n";
echo "                                      ← right-to-left →\n";
echo "                    Column order creates NATURAL swap\n\n";

echo "Result: SINGLE (NATURAL) SWAP = CORRECT\n";
echo "  Horizontal: 101111001111100\n";
echo "  Vertical:   101111001111100\n";
echo "              ─────────────── PERFECT MATCH! ✅\n\n\n";

echo "KEY INSIGHT:\n";
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\n";
echo "The swap happens NATURALLY due to column order!\n";
echo "  - Columns 0-8: Left-to-right (sequential)\n";
echo "  - Columns 20-14: Right-to-left (reversed)\n";
echo "\n";
echo "When you place bits SEQUENTIALLY at these columns,\n";
echo "the right-to-left section creates the swap effect.\n";
echo "\n";
echo "Manually swapping bits BEFORE placement creates\n";
echo "DOUBLE swapping, which is INCORRECT.\n";
echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━\n\n";

echo "Code Change Summary:\n";
echo "─────────────────────────────────────────────\n";
echo "// BEFORE (WRONG)\n";
echo "\$bitIndices = [0,1,2,3,4,5,6,7,8,10,9,11,13,12,14];\n";
echo "for (\$i = 0; \$i < 15; \$i++) {\n";
echo "    \$bitIndex = \$bitIndices[\$i]; // Manual swap\n";
echo "    \$bit = (\$formatBits >> (14 - \$bitIndex)) & 1;\n";
echo "}\n\n";

echo "// AFTER (CORRECT)\n";
echo "for (\$i = 0; \$i < 15; \$i++) {\n";
echo "    \$bit = (\$formatBits >> (14 - \$i)) & 1; // Sequential\n";
echo "}\n\n";