eepro100: Use symbolic names and BIT macros in binary operations

Instead of magic numbers like 0x8000, symbolic names are used
for the SCB command and status bits.

There are too many configuration bits to use symbolic names
there, too. Using the BIT macro is a little help when comparing
code and documentation.

For the same reason, some other constants were replaced by
the BITS macro.

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/eepro100.c

diff --git a/hw/eepro100.c b/hw/eepro100.c
index d5d3abc..a58c640 100644
--- a/hw/eepro100.c
+++ b/hw/eepro100.c
@@ -172,6 +172,20 @@
     char packet[MAX_ETH_FRAME_SIZE + 4];
 } eepro100_rx_t;
 
+typedef enum {
+    COMMAND_EL = BIT(15),
+    COMMAND_S = BIT(14),
+    COMMAND_I = BIT(13),
+    COMMAND_NC = BIT(4),
+    COMMAND_SF = BIT(3),
+    COMMAND_CMD = BITS(2, 0),
+} scb_command_bit;
+
+typedef enum {
+    STATUS_C = BIT(15),
+    STATUS_OK = BIT(13),
+} scb_status_bit;
+
 typedef struct {
     uint32_t tx_good_frames, tx_max_collisions, tx_late_collisions,
         tx_underruns, tx_lost_crs, tx_deferred, tx_single_collisions,
@@ -753,22 +767,22 @@
 
 static cu_state_t get_cu_state(EEPRO100State * s)
 {
-    return ((s->mem[SCBStatus] >> 6) & 0x03);
+    return ((s->mem[SCBStatus] & BITS(7, 6)) >> 6);
 }
 
 static void set_cu_state(EEPRO100State * s, cu_state_t state)
 {
-    s->mem[SCBStatus] = (s->mem[SCBStatus] & 0x3f) + (state << 6);
+    s->mem[SCBStatus] = (s->mem[SCBStatus] & ~BITS(7, 6)) + (state << 6);
 }
 
 static ru_state_t get_ru_state(EEPRO100State * s)
 {
-    return ((s->mem[SCBStatus] >> 2) & 0x0f);
+    return ((s->mem[SCBStatus] & BITS(5, 2)) >> 2);
 }
 
 static void set_ru_state(EEPRO100State * s, ru_state_t state)
 {
-    s->mem[SCBStatus] = (s->mem[SCBStatus] & 0xc3) + (state << 2);
+    s->mem[SCBStatus] = (s->mem[SCBStatus] & ~BITS(5, 2)) + (state << 2);
 }
 
 static void dump_statistics(EEPRO100State * s)
@@ -898,13 +912,13 @@
         uint16_t command = le16_to_cpu(s->tx.command);
         logout("val=(cu start), status=0x%04x, command=0x%04x, link=0x%08x\n",
                status, command, s->tx.link);
-        bool bit_el = ((command & 0x8000) != 0);
-        bool bit_s = ((command & 0x4000) != 0);
-        bool bit_i = ((command & 0x2000) != 0);
-        bool bit_nc = ((command & 0x0010) != 0);
+        bool bit_el = ((command & COMMAND_EL) != 0);
+        bool bit_s = ((command & COMMAND_S) != 0);
+        bool bit_i = ((command & COMMAND_I) != 0);
+        bool bit_nc = ((command & COMMAND_NC) != 0);
         bool success = true;
-        //~ bool bit_sf = ((command & 0x0008) != 0);
-        uint16_t cmd = command & 0x0007;
+        //~ bool bit_sf = ((command & COMMAND_SF) != 0);
+        uint16_t cmd = command & COMMAND_CMD;
         s->cu_offset = le32_to_cpu(s->tx.link);
         switch (cmd) {
         case CmdNOp:
@@ -941,7 +955,7 @@
             break;
         }
         /* Write new status. */
-        stw_phys(s->cb_address, status | 0x8000 | (success ? 0x2000 : 0));
+        stw_phys(s->cb_address, status | STATUS_C | (success ? STATUS_OK : 0));
         if (bit_i) {
             /* CU completed action. */
             eepro100_cx_interrupt(s);
@@ -1684,13 +1698,13 @@
         /* CSMA is disabled. */
         logout("%p received while CSMA is disabled\n", s);
         return -1;
-    } else if (size < 64 && (s->configuration[7] & 1)) {
+    } else if (size < 64 && (s->configuration[7] & BIT(0))) {
         /* Short frame and configuration byte 7/0 (discard short receive) set:
          * Short frame is discarded */
         logout("%p received short frame (%zu byte)\n", s, size);
         s->statistics.rx_short_frame_errors++;
         //~ return -1;
-    } else if ((size > MAX_ETH_FRAME_SIZE + 4) && !(s->configuration[18] & 8)) {
+    } else if ((size > MAX_ETH_FRAME_SIZE + 4) && !(s->configuration[18] & BIT(3))) {
         /* Long frame and configuration byte 18/3 (long receive ok) not set:
          * Long frames are discarded. */
         logout("%p received long frame (%zu byte), ignored\n", s, size);
@@ -1713,7 +1727,7 @@
           assert(mcast_idx < 64);
           if (s->mult[mcast_idx >> 3] & (1 << (mcast_idx & 7))) {
             /* Multicast frame is allowed in hash table. */
-          } else if (s->configuration[15] & 1) {
+          } else if (s->configuration[15] & BIT(0)) {
               /* Promiscuous: receive all. */
               rfd_status |= 0x0004;
           } else {
@@ -1723,7 +1737,7 @@
         }
         /* TODO: Next not for promiscuous mode? */
         rfd_status |= 0x0002;
-    } else if (s->configuration[15] & 1) {
+    } else if (s->configuration[15] & BIT(0)) {
         /* Promiscuous: receive all. */
         TRACE(RXTX, logout("%p received frame in promiscuous mode, len=%zu\n", s, size));
         rfd_status |= 0x0004;
@@ -1764,23 +1778,23 @@
     /* Early receive interrupt not supported. */
     //~ eepro100_er_interrupt(s);
     /* Receive CRC Transfer not supported. */
-    if (s->configuration[18] & 4) {
+    if (s->configuration[18] & BIT(2)) {
         missing("Receive CRC Transfer");
         return -1;
     }
     /* TODO: check stripping enable bit. */
-    //~ assert(!(s->configuration[17] & 1));
+    //~ assert(!(s->configuration[17] & BIT(0)));
     cpu_physical_memory_write(s->ru_base + s->ru_offset +
                               offsetof(eepro100_rx_t, packet), buf, size);
     s->statistics.rx_good_frames++;
     eepro100_fr_interrupt(s);
     s->ru_offset = le32_to_cpu(rx.link);
-    if (rfd_command & 0x8000) {
+    if (rfd_command & COMMAND_EL) {
         /* EL bit is set, so this was the last frame. */
         logout("receive: Running out of frames\n");
         set_ru_state(s, ru_suspended);
     }
-    if (rfd_command & 0x4000) {
+    if (rfd_command & COMMAND_S) {
         /* S bit is set. */
         set_ru_state(s, ru_suspended);
     }