1 files changed, 45 insertions, 0 deletions
diff --git a/src/gpio.zig b/src/gpio.zig
new file mode 100644
index 0000000..1d713e6
--- /dev/null
+++ b/src/gpio.zig
@@ -0,0 +1,45 @@
+const registers = packed struct {
+    moder: u32,
+    otyper: u32,
+    ospeedr: u32,
+    pupdr: u32,
+    idr: u32,
+    odr: u32,
+    bsrr: u32,
+    lckr: u32,
+    afrl: u32,
+    afrh: u32,
+    brr: u32,
+    ascr: u32,
+};
+
+const driver = struct {
+    port: *registers,
+
+    const mode = enum {
+        input,
+        output,
+        alternate,
+        analog,
+    };
+
+    pub fn set_mode(self: driver, pin: u4, m: mode) void {
+        self.port.moder &= ~(@as(u32, 0x3) << (2 * pin));
+
+        const mask: u32 = switch (m) {
+            .input => 0,
+            .output => 1,
+            .alternate => 2,
+            .analog => 3
+        };
+
+        self.port.moder |= mask << (2 * pin);
+    }
+
+    pub fn toggle(self: driver, pin: u4) void {
+        self.port.odr ^= @as(u32, 1) << pin;
+    }
+};
+
+pub const gpioa = driver { .port = @ptrFromInt(0x48000000) };
+