diff --git a/.vscode/settings.json b/.vscode/settings.json
index 89a936c..1a2508a 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -40,6 +40,7 @@
         "__config": "c",
         "string": "c",
         "atomic": "c",
-        "__bit_reference": "c"
+        "__bit_reference": "c",
+        "err.h": "c"
     }
 }
\ No newline at end of file
diff --git a/port/ethernetif.c b/port/ethernetif.c
index 7e7fe6c..ef6f906 100644
--- a/port/ethernetif.c
+++ b/port/ethernetif.c
@@ -13,12 +13,6 @@
 #define IFNAME0 'e'
 #define IFNAME1 'n'
 
-#define ETH_RX_BUF_COUNT 4
-#define ETH_TX_BUF_COUNT 2
-/* buf size should be at least ETH_MAX_PACKET_SIZE */
-#define ETH_RX_BUF_SIZE ETH_MAX_PACKET_SIZE
-#define ETH_TX_BUF_SIZE ETH_MAX_PACKET_SIZE
-
 typedef struct {
   volatile uint32_t head;  // producer idx: next free slot to write to
   volatile uint32_t tail;  // consumer idx: next slot to be txed
@@ -216,12 +210,10 @@ static err_t low_level_output(struct netif* netif, struct pbuf* p) {
     }
 
     g_dma_tx_descs[current_idx].Status = len;
-
     tx_queue_produce(&ethernetif->tx_q);
   }
 
   tx_start_if_possible();
-
   return errval;
 }
 
@@ -310,7 +302,8 @@ void ETH_IRQHandler(void) {
         ethernetif->rx_desc_head->Status &= ~ETH_DMARxDesc_OWN;
         // write packet len into status field for CPU
         ethernetif->rx_desc_head->Status |=
-            (ETH_DMARxDesc_FS | ETH_DMARxDesc_LS | (ETH10M->ERXLN << 16));
+            (ETH_DMARxDesc_FS | ETH_DMARxDesc_LS |
+             (ETH10M->ERXLN << ETH_DMARxDesc_FrameLengthShift));
         // advance descripotor ptr
         ethernetif->rx_desc_head = next_desc;
         // re-arm receiver with new emtpy buf
diff --git a/port/ethernetif.h b/port/ethernetif.h
index 00c0fee..75c2cee 100644
--- a/port/ethernetif.h
+++ b/port/ethernetif.h
@@ -4,25 +4,32 @@
 #include "lwip/err.h"
 #include "lwip/netif.h"
 
-void phy_write_reg(uint8_t reg_add, uint16_t reg_val);
-uint16_t phy_read_reg(uint8_t reg_add);
-
+/* Unique device ID */
 #define ROM_CFG_USERADR_ID 0x1FFFF7E8
 
-#define ETH_DMARxDesc_FrameLengthShift 16
-
-#define ETH_MAX_PACKET_SIZE \
-  1536 /* ETH_HEADER + VLAN_TAG + MAX_ETH_PAYLOAD + ETH_CRC */
-#define ETH_HEADER                                                           \
-  14                /* 6 byte Dest addr, 6 byte Src addr, 2 byte length/type \
-                     */
+/* Ethernet Frame Size Definitions */
+#define ETH_HEADER \
+  14                /* 6 byte Dest addr, 6 byte Src addr, 2 byte length/type */
 #define ETH_CRC 4   /* Ethernet CRC */
 #define ETH_EXTRA 2 /* Extra bytes in some cases */
 #define VLAN_TAG 4  /* optional 802.1q VLAN Tag */
+
 #define MIN_ETH_PAYLOAD 46   /* Minimum Ethernet payload size */
 #define MAX_ETH_PAYLOAD 1500 /* Maximum Ethernet payload size */
+
+#define ETH_MAX_PACKET_SIZE \
+  1536 /* ETH_HEADER + VLAN_TAG + MAX_ETH_PAYLOAD + ETH_CRC */
 #define MIN_ETH_FRAME_SIZE (ETH_HEADER + MIN_ETH_PAYLOAD) /* 60 bytes */
 
+/* Buffer Configuration */
+#define ETH_RX_BUF_COUNT 4
+#define ETH_TX_BUF_COUNT 2
+#define ETH_RX_BUF_SIZE ETH_MAX_PACKET_SIZE
+#define ETH_TX_BUF_SIZE ETH_MAX_PACKET_SIZE
+
+/* DMA descriptor stuff */
+#define ETH_DMARxDesc_FrameLengthShift 16
+
 typedef struct {
   uint32_t volatile Status;     /* Status */
   uint32_t ControlBufferSize;   /* Control and Buffer1, Buffer2 lengths */
@@ -31,29 +38,52 @@ typedef struct {
 } ETH_DMADESCTypeDef;
 
 /**
- * @brief Initialize the ethernet interface and lwIP network stack.
- *        This function should be passed as the init function to netif_add().
+ * Should be called at the beginning of the program to set up the
+ * network interface. It calls the function low_level_init() to do the
+ * actual setup of the hardware.
  *
- * @param netif The lwIP network interface structure to be initialized.
- * @return ERR_OK if the loopif is initialized, ERR_MEM if private data couldn't
- * be allocated.
+ * This function should be passed as a parameter to netif_add().
+ *
+ * @param netif the lwip network interface structure for this ethernetif
+ * @return ERR_OK if the loopif is initialized
+ *         ERR_MEM if private data couldn't be allocated
+ *         any other err_t on error
  */
 err_t ethernetif_init(struct netif* netif);
 
 /**
- * @brief This function should be called periodically from your main loop
- *        to check for incoming packets and pass them to lwIP.
+ * This function should be called when a packet is ready to be read
+ * from the interface. It uses the function low_level_input() that
+ * should handle the actual reception of bytes from the network
+ * interface. Then the type of the received packet is determined and
+ * the appropriate input function is called.
  *
- * @param netif The lwIP network interface structure.
+ * @param netif the lwip network interface structure for this ethernetif
  */
 void ethernetif_input(struct netif* netif);
 
 /**
- * @brief This function should be called periodically from your main loop
- *        to check the link status and update lwIP accordingly.
+ * This function should be called periodically from the main loop
+ * to check the link status and update lwIP accordingly.
  *
- * @param netif The lwIP network interface structure..
+ * @param netif the lwip network interface structure for this ethernetif
  */
 void ethernetif_link_poll(struct netif* netif);
 
+/**
+ * Write a value to PHY register.
+ *
+ * @param reg_add PHY register address.
+ * @param reg_val Value to write.
+ */
+void phy_write_reg(uint8_t reg_add, uint16_t reg_val);
+
+/**
+ * Read a value from PHY register.
+ *
+ * @param reg_add PHY register address.
+ * @return Register value.
+ */
+uint16_t phy_read_reg(uint8_t reg_add);
+
 #endif /* __ETHERNETIF_H */
\ No newline at end of file