1 files changed, 58 insertions, 0 deletions
diff --git a/src/Field.php b/src/Field.php
new file mode 100644
index 0000000..9e11bad
--- /dev/null
+++ b/src/Field.php
@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Zhineng\Snowflake;
+
+abstract class Field implements Component
+{
+    /**
+     * The bit offset.
+     */
+    private int $offset = 0;
+
+    public function __construct(
+        public readonly string $name,
+        public readonly int $bits,
+    ) {
+        if ($bits < 1 || $bits > 63) {
+            throw new \InvalidArgumentException('Bits must be between 1 and 63.');
+        }
+    }
+
+    /**
+     * The bit size.
+     */
+    public function bits(): int
+    {
+        return $this->bits;
+    }
+
+    /**
+     * The maximum value based on the number of bits.
+     */
+    public function maxValue(): int
+    {
+        return (1 << $this->bits) - 1;
+    }
+
+    /**
+     * Set the bit offset.
+     */
+    public function setOffset(int $offset): static
+    {
+        $this->offset = $offset;
+
+        return $this;
+    }
+
+    /**
+     * The bit offset.
+     */
+    public function offset(): int
+    {
+        return $this->offset;
+    }
+
+    abstract public function value(): int;
+}