diff --git a/hw/net/e1000.c b/hw/net/e1000.c
index 9619a2e..0925a99 100644
--- a/hw/net/e1000.c
+++ b/hw/net/e1000.c
@@ -1063,30 +1063,6 @@
 }
 
 static uint32_t
-mac_low4_read(E1000State *s, int index)
-{
-    return s->mac_reg[index] & 0xf;
-}
-
-static uint32_t
-mac_low11_read(E1000State *s, int index)
-{
-    return s->mac_reg[index] & 0x7ff;
-}
-
-static uint32_t
-mac_low13_read(E1000State *s, int index)
-{
-    return s->mac_reg[index] & 0x1fff;
-}
-
-static uint32_t
-mac_low16_read(E1000State *s, int index)
-{
-    return s->mac_reg[index] & 0xffff;
-}
-
-static uint32_t
 mac_icr_read(E1000State *s, int index)
 {
     uint32_t ret = s->mac_reg[ICR];
@@ -1138,11 +1114,17 @@
     }
 }
 
-static void
-set_16bit(E1000State *s, int index, uint32_t val)
-{
-    s->mac_reg[index] = val & 0xffff;
-}
+#define LOW_BITS_SET_FUNC(num)                             \
+    static void                                            \
+    set_##num##bit(E1000State *s, int index, uint32_t val) \
+    {                                                      \
+        s->mac_reg[index] = val & (BIT(num) - 1);          \
+    }
+
+LOW_BITS_SET_FUNC(4)
+LOW_BITS_SET_FUNC(11)
+LOW_BITS_SET_FUNC(13)
+LOW_BITS_SET_FUNC(16)
 
 static void
 set_dlen(E1000State *s, int index, uint32_t val)
@@ -1196,7 +1178,9 @@
     getreg(XONRXC),   getreg(XONTXC),   getreg(XOFFRXC),  getreg(XOFFTXC),
     getreg(RFC),      getreg(RJC),      getreg(RNBC),     getreg(TSCTFC),
     getreg(MGTPRC),   getreg(MGTPDC),   getreg(MGTPTC),   getreg(GORCL),
-    getreg(GOTCL),
+    getreg(GOTCL),    getreg(RDFH),     getreg(RDFT),     getreg(RDFHS),
+    getreg(RDFTS),    getreg(RDFPC),    getreg(TDFH),     getreg(TDFT),
+    getreg(TDFHS),    getreg(TDFTS),    getreg(TDFPC),    getreg(AIT),
 
     [TOTH]    = mac_read_clr8,      [TORH]    = mac_read_clr8,
     [GOTCH]   = mac_read_clr8,      [GORCH]   = mac_read_clr8,
@@ -1214,22 +1198,15 @@
     [MPTC]    = mac_read_clr4,
     [ICR]     = mac_icr_read,       [EECD]    = get_eecd,
     [EERD]    = flash_eerd_read,
-    [RDFH]    = mac_low13_read,     [RDFT]    = mac_low13_read,
-    [RDFHS]   = mac_low13_read,     [RDFTS]   = mac_low13_read,
-    [RDFPC]   = mac_low13_read,
-    [TDFH]    = mac_low11_read,     [TDFT]    = mac_low11_read,
-    [TDFHS]   = mac_low13_read,     [TDFTS]   = mac_low13_read,
-    [TDFPC]   = mac_low13_read,
-    [AIT]     = mac_low16_read,
 
     [CRCERRS ... MPC]     = &mac_readreg,
     [IP6AT ... IP6AT + 3] = &mac_readreg,    [IP4AT ... IP4AT + 6] = &mac_readreg,
-    [FFLT ... FFLT + 6]   = &mac_low11_read,
+    [FFLT ... FFLT + 6]   = &mac_readreg,
     [RA ... RA + 31]      = &mac_readreg,
     [WUPM ... WUPM + 31]  = &mac_readreg,
     [MTA ... MTA + 127]   = &mac_readreg,
     [VFTA ... VFTA + 127] = &mac_readreg,
-    [FFMT ... FFMT + 254] = &mac_low4_read,
+    [FFMT ... FFMT + 254] = &mac_readreg,
     [FFVT ... FFVT + 254] = &mac_readreg,
     [PBM ... PBM + 16383] = &mac_readreg,
 };
@@ -1241,26 +1218,27 @@
     putreg(PBA),      putreg(EERD),     putreg(SWSM),     putreg(WUFC),
     putreg(TDBAL),    putreg(TDBAH),    putreg(TXDCTL),   putreg(RDBAH),
     putreg(RDBAL),    putreg(LEDCTL),   putreg(VET),      putreg(FCRUC),
-    putreg(TDFH),     putreg(TDFT),     putreg(TDFHS),    putreg(TDFTS),
-    putreg(TDFPC),    putreg(RDFH),     putreg(RDFT),     putreg(RDFHS),
-    putreg(RDFTS),    putreg(RDFPC),    putreg(IPAV),     putreg(WUC),
-    putreg(WUS),      putreg(AIT),
+    putreg(IPAV),     putreg(WUC),
+    putreg(WUS),
 
-    [TDLEN]  = set_dlen,   [RDLEN]  = set_dlen,       [TCTL] = set_tctl,
-    [TDT]    = set_tctl,   [MDIC]   = set_mdic,       [ICS]  = set_ics,
-    [TDH]    = set_16bit,  [RDH]    = set_16bit,      [RDT]  = set_rdt,
-    [IMC]    = set_imc,    [IMS]    = set_ims,        [ICR]  = set_icr,
-    [EECD]   = set_eecd,   [RCTL]   = set_rx_control, [CTRL] = set_ctrl,
-    [RDTR]   = set_16bit,  [RADV]   = set_16bit,      [TADV] = set_16bit,
-    [ITR]    = set_16bit,
+    [TDLEN]  = set_dlen,   [RDLEN]  = set_dlen,       [TCTL]  = set_tctl,
+    [TDT]    = set_tctl,   [MDIC]   = set_mdic,       [ICS]   = set_ics,
+    [TDH]    = set_16bit,  [RDH]    = set_16bit,      [RDT]   = set_rdt,
+    [IMC]    = set_imc,    [IMS]    = set_ims,        [ICR]   = set_icr,
+    [EECD]   = set_eecd,   [RCTL]   = set_rx_control, [CTRL]  = set_ctrl,
+    [RDTR]   = set_16bit,  [RADV]   = set_16bit,      [TADV]  = set_16bit,
+    [ITR]    = set_16bit,  [TDFH]   = set_11bit,      [TDFT]  = set_11bit,
+    [TDFHS]  = set_13bit,  [TDFTS]  = set_13bit,      [TDFPC] = set_13bit,
+    [RDFH]   = set_13bit,  [RDFT]   = set_13bit,      [RDFHS] = set_13bit,
+    [RDFTS]  = set_13bit,  [RDFPC]  = set_13bit,      [AIT]   = set_16bit,
 
     [IP6AT ... IP6AT + 3] = &mac_writereg, [IP4AT ... IP4AT + 6] = &mac_writereg,
-    [FFLT ... FFLT + 6]   = &mac_writereg,
+    [FFLT ... FFLT + 6]   = &set_11bit,
     [RA ... RA + 31]      = &mac_writereg,
     [WUPM ... WUPM + 31]  = &mac_writereg,
     [MTA ... MTA + 127]   = &mac_writereg,
     [VFTA ... VFTA + 127] = &mac_writereg,
-    [FFMT ... FFMT + 254] = &mac_writereg, [FFVT ... FFVT + 254] = &mac_writereg,
+    [FFMT ... FFMT + 254] = &set_4bit,     [FFVT ... FFVT + 254] = &mac_writereg,
     [PBM ... PBM + 16383] = &mac_writereg,
 };