From 597d2584b1caa0adf5d63245bc195902f5cd34ad Mon Sep 17 00:00:00 2001
From: Zac Wilson <zac@zacjw.com>
Date: Mon, 22 Dec 2025 17:17:34 +0000
Subject: [PATCH] Wrote MatrixConfig type

---
 src/lib.rs | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index d0135ae..157d396 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,3 +8,46 @@ pub struct TCA8418<I2C> {
     i2c: I2C,
 }
 
+#[derive(Clone, Copy)]
+pub struct MatrixConfig {
+    rows: u8,
+    columns: u16,
+}
+
+impl MatrixConfig {
+    /// A new config where the matrix has no rows or columns and all of the pins are
+    /// allocated for GPIO.
+    pub const fn new_empty() -> Self {
+        MatrixConfig {
+            rows: 0,
+            columns: 0,
+        }
+    }
+
+    /// Add a row to the keyboard matrix, meaning its pin will not be available for GPIO.
+    ///
+    /// `row_number` must be in the range `0..=7`
+    pub const fn with_row(self, row_number: u8) -> Self {
+        if row_number >= 8 {
+            panic!("row_number out of bounds");
+        }
+        MatrixConfig {
+            rows: self.rows | (1 << row_number),
+            columns: self.columns,
+        }
+    }
+
+    /// Add a column to the keyboard matrix, meaning its pin will not be available for GPIO.
+    ///
+    /// `column_number` must be in the range `0..=9`
+    pub const fn with_column(self, column_number: u8) -> Self {
+        if column_number >= 10 {
+            panic!("column_number out of bounds");
+        }
+        MatrixConfig {
+            rows: self.rows,
+            columns: self.columns | (1 << column_number),
+        }
+    }
+}
+