sky2: use mask instead of modulo operation

Gcc isn't smart enough to know that it can do a modulo
operation with power of 2 constant by doing a mask.
So add macro to do it for us.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index 4bb6ea1..d9cce50 100644 (file)
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -79,6 +79,8 @@
 #define NAPI_WEIGHT            64
 #define PHY_RETRIES            1000
 
+#define RING_NEXT(x,s) (((x)+1) & ((s)-1))
+
 static const u32 default_msg =
     NETIF_MSG_DRV | NETIF_MSG_PROBE | NETIF_MSG_LINK
     | NETIF_MSG_TIMER | NETIF_MSG_TX_ERR | NETIF_MSG_RX_ERR
@@ -719,7 +721,7 @@ static inline struct sky2_tx_le *get_tx_le(struct sky2_port *sky2)
 {
        struct sky2_tx_le *le = sky2->tx_le + sky2->tx_prod;
 
-       sky2->tx_prod = (sky2->tx_prod + 1) % TX_RING_SIZE;
+       sky2->tx_prod = RING_NEXT(sky2->tx_prod, TX_RING_SIZE);
        return le;
 }
 
@@ -735,7 +737,7 @@ static inline void sky2_put_idx(struct sky2_hw *hw, unsigned q, u16 idx)
 static inline struct sky2_rx_le *sky2_next_rx(struct sky2_port *sky2)
 {
        struct sky2_rx_le *le = sky2->rx_le + sky2->rx_put;
-       sky2->rx_put = (sky2->rx_put + 1) % RX_LE_SIZE;
+       sky2->rx_put = RING_NEXT(sky2->rx_put, RX_LE_SIZE);
        return le;
 }
 
@@ -1078,7 +1080,7 @@ err_out:
 /* Modular subtraction in ring */
 static inline int tx_dist(unsigned tail, unsigned head)
 {
-       return (head - tail) % TX_RING_SIZE;
+       return (head - tail) & (TX_RING_SIZE - 1);
 }
 
 /* Number of list elements available for next tx */
@@ -1255,7 +1257,7 @@ static int sky2_xmit_frame(struct sk_buff *skb, struct net_device *dev)
                le->opcode = OP_BUFFER | HW_OWNER;
 
                fre = sky2->tx_ring
-                   + ((re - sky2->tx_ring) + i + 1) % TX_RING_SIZE;
+                   + RING_NEXT((re - sky2->tx_ring) + i, TX_RING_SIZE);
                pci_unmap_addr_set(fre, mapaddr, mapping);
        }
 
@@ -1315,7 +1317,7 @@ static void sky2_tx_complete(struct sky2_port *sky2, u16 done)
 
                for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
                        struct tx_ring_info *fre;
-                       fre = sky2->tx_ring + (put + i + 1) % TX_RING_SIZE;
+                       fre = sky2->tx_ring + RING_NEXT(put + i, TX_RING_SIZE);
                        pci_unmap_page(pdev, pci_unmap_addr(fre, mapaddr),
                                       skb_shinfo(skb)->frags[i].size,
                                       PCI_DMA_TODEVICE);
@@ -1876,7 +1878,7 @@ static int sky2_status_intr(struct sky2_hw *hw, int to_do)
                        break;
                opcode &= ~HW_OWNER;
 
-               hw->st_idx = (hw->st_idx + 1) % STATUS_RING_SIZE;
+               hw->st_idx = RING_NEXT(hw->st_idx, STATUS_RING_SIZE);
                le->opcode = 0;
 
                link = le->link;