diff --git a/build.zig b/build.zig
index eacdb1e..00d19c4 100644
--- a/build.zig
+++ b/build.zig
@@ -12,7 +12,8 @@ pub fn build(b: *std.Build) void {
         .name = "stm32",
         .root_source_file = b.path("src/main.zig"),
         .target = target,
-        .optimize = .Debug, // .ReleaseSmall,
+        //.optimize = .Debug,
+        .optimize = .ReleaseSafe,
         .linkage = .static,
     });
 
diff --git a/src/gpio.zig b/src/gpio.zig
index cbb20fa..c0bf6ba 100644
--- a/src/gpio.zig
+++ b/src/gpio.zig
@@ -1,4 +1,26 @@
-const registers = packed struct {
+const mode = enum(u32) {
+    alternate_0 = 0,
+    alternate_1,
+    alternate_2,
+    alternate_3,
+    alternate_4,
+    alternate_5,
+    alternate_6,
+    alternate_7,
+    alternate_8,
+    alternate_9,
+    alternate_10,
+    alternate_11,
+    alternate_12,
+    alternate_13,
+    alternate_14,
+    alternate_15,
+    input,
+    output,
+    analog,
+};
+
+const driver_stm32 = packed struct {
     moder: u32,
     otyper: u32,
     ospeedr: u32,
@@ -10,36 +32,10 @@ const registers = packed struct {
     afr: u64,
     brr: u32,
     ascr: u32,
-};
-
-const driver = struct {
-    port: *registers,
-
-    const mode = enum(u32) {
-        alternate_0 = 0,
-        alternate_1,
-        alternate_2,
-        alternate_3,
-        alternate_4,
-        alternate_5,
-        alternate_6,
-        alternate_7,
-        alternate_8,
-        alternate_9,
-        alternate_10,
-        alternate_11,
-        alternate_12,
-        alternate_13,
-        alternate_14,
-        alternate_15,
-        input,
-        output,
-        analog,
-    };
 
-    pub fn set_mode(self: driver, pin: u4, m: mode) void {
+    pub fn set_mode(self: *driver_stm32, pin: u4, m: mode) void {
         const offset = 2 * @as(u5, pin);
-        const moder = self.port.moder & ~(@as(u32, 3) << offset);
+        const moder = self.moder & ~(@as(u32, 3) << offset);
 
         const mask: u32 = switch (m) {
             .input => 0,
@@ -48,28 +44,28 @@ const driver = struct {
             else => 2,
         };
 
-        self.port.moder = moder | (mask << offset);
+        self.moder = moder | (mask << offset);
 
         if (mask == 2) {
             const afr_offset = (4 * @as(u6, pin));
-            const afr = self.port.afr & ~(@as(u64, 0xF) << afr_offset);
-            self.port.afr = afr | (@as(u64, @intFromEnum(m)) << afr_offset);
+            const afr = self.afr & ~(@as(u64, 0xF) << afr_offset);
+            self.afr = afr | (@as(u64, @intFromEnum(m)) << afr_offset);
         }
     }
 
-    pub fn toggle(self: driver, pin: u4) void {
-        self.port.odr ^= @as(u32, 1) << pin;
+    pub fn toggle(self: *driver_stm32, pin: u4) void {
+        self.odr ^= @as(u32, 1) << pin;
     }
 
-    pub fn set(self: driver, pin: u4) void {
-        self.port.odr |= @as(u32, 1) << pin;
+    pub fn set(self: *driver_stm32, pin: u4) void {
+        self.odr |= @as(u32, 1) << pin;
     }
 
-    pub fn clear(self: driver, pin: u4) void {
-        self.port.odr &= ~(@as(u32, 1) << pin);
+    pub fn clear(self: *driver_stm32, pin: u4) void {
+        self.odr &= ~(@as(u32, 1) << pin);
     }
 
-    pub fn write(self: driver, pin: u4, val: bool) void {
+    pub fn write(self: *driver_stm32, pin: u4, val: bool) void {
         if (val) {
             self.set(pin);
         } else {
@@ -77,17 +73,47 @@ const driver = struct {
         }
     }
 
+    pub fn read(self: driver_stm32, pin: u4) bool {
+        return (self.idr & @as(u32, 1) << pin) != 0;
+    }
+};
+
+const driver = struct {
+    const lld_type = driver_stm32;
+
+    lld: *lld_type,
+
+    pub fn set_mode(self: driver, pin: u4, m: mode) void {
+        self.lld.set_mode(pin, m);
+    }
+
+    pub fn toggle(self: driver, pin: u4) void {
+        self.lld.toggle(pin);
+    }
+
+    pub fn set(self: driver, pin: u4) void {
+        self.lld.set(pin);
+    }
+
+    pub fn clear(self: driver, pin: u4) void {
+        self.lld.clear(pin);
+    }
+
+    pub fn write(self: driver, pin: u4, val: bool) void {
+        self.lld.write(pin, val);
+    }
+
     pub fn read(self: driver, pin: u4) bool {
-        return (self.port.idr & @as(u32, 1) << pin) != 0;
+        return self.lld.read(pin);
     }
 };
 
-pub const gpioa = driver { .port = @ptrFromInt(0x48000000) };
-pub const gpiob = driver { .port = @ptrFromInt(0x48000400) };
-pub const gpioc = driver { .port = @ptrFromInt(0x48000800) };
-pub const gpiod = driver { .port = @ptrFromInt(0x48000C00) };
-pub const gpioe = driver { .port = @ptrFromInt(0x48001000) };
-pub const gpiof = driver { .port = @ptrFromInt(0x48001400) };
-pub const gpiog = driver { .port = @ptrFromInt(0x48001800) };
-pub const gpioh = driver { .port = @ptrFromInt(0x48001C00) };
+pub const gpioa = driver { .lld = @ptrFromInt(0x48000000) };
+pub const gpiob = driver { .lld = @ptrFromInt(0x48000400) };
+pub const gpioc = driver { .lld = @ptrFromInt(0x48000800) };
+pub const gpiod = driver { .lld = @ptrFromInt(0x48000C00) };
+pub const gpioe = driver { .lld = @ptrFromInt(0x48001000) };
+pub const gpiof = driver { .lld = @ptrFromInt(0x48001400) };
+pub const gpiog = driver { .lld = @ptrFromInt(0x48001800) };
+pub const gpioh = driver { .lld = @ptrFromInt(0x48001C00) };