Re: [Qemu-devel] [PATCHv3 04/13] eepro100: switch eepro100 e100_compute_mcast_idx() over to use net_crc32()

[Philippe Mathieu-Daudé]

On 12/15/2017 03:41 PM, Mark Cave-Ayland wrote:
> Instead of e100_compute_mcast_idx() using its own implementation, we can
> simply call net_crc32() directly and apply the bit shift inline.
> 
> Signed-off-by: Mark Cave-Ayland <address@hidden>
> Reviewed-by: Stefan Weil <address@hidden>

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

> ---
>  hw/net/eepro100.c | 28 ++++------------------------
>  1 file changed, 4 insertions(+), 24 deletions(-)
> 
> diff --git a/hw/net/eepro100.c b/hw/net/eepro100.c
> index 71cddfece4..e30fed830b 100644
> --- a/hw/net/eepro100.c
> +++ b/hw/net/eepro100.c
> @@ -44,6 +44,7 @@
>  #include "hw/hw.h"
>  #include "hw/pci/pci.h"
>  #include "net/net.h"
> +#include "net/eth.h"
>  #include "hw/nvram/eeprom93xx.h"
>  #include "sysemu/sysemu.h"
>  #include "sysemu/dma.h"
> @@ -325,28 +326,6 @@ static const uint16_t eepro100_mdi_mask[] = {
>  
>  static E100PCIDeviceInfo *eepro100_get_class(EEPRO100State *s);
>  
> -/* From FreeBSD (locally modified). */
> -static unsigned e100_compute_mcast_idx(const uint8_t *ep)
> -{
> -    uint32_t crc;
> -    int carry, i, j;
> -    uint8_t b;
> -
> -    crc = 0xffffffff;
> -    for (i = 0; i < 6; i++) {
> -        b = *ep++;
> -        for (j = 0; j < 8; j++) {
> -            carry = ((crc & 0x80000000L) ? 1 : 0) ^ (b & 0x01);
> -            crc <<= 1;
> -            b >>= 1;
> -            if (carry) {
> -                crc = ((crc ^ POLYNOMIAL_BE) | carry);
> -            }
> -        }
> -    }
> -    return (crc & BITS(7, 2)) >> 2;
> -}
> -
>  /* Read a 16 bit control/status (CSR) register. */
>  static uint16_t e100_read_reg2(EEPRO100State *s, E100RegisterOffset addr)
>  {
> @@ -843,7 +822,8 @@ static void set_multicast_list(EEPRO100State *s)
>          uint8_t multicast_addr[6];
>          pci_dma_read(&s->dev, s->cb_address + 10 + i, multicast_addr, 6);
>          TRACE(OTHER, logout("multicast entry %s\n", nic_dump(multicast_addr, 
> 6)));
> -        unsigned mcast_idx = e100_compute_mcast_idx(multicast_addr);
> +        unsigned mcast_idx = (net_crc32(multicast_addr, ETH_ALEN) &
> +                              BITS(7, 2)) >> 2;
>          assert(mcast_idx < 64);
>          s->mult[mcast_idx >> 3] |= (1 << (mcast_idx & 7));
>      }
> @@ -1679,7 +1659,7 @@ static ssize_t nic_receive(NetClientState *nc, const 
> uint8_t * buf, size_t size)
>          if (s->configuration[21] & BIT(3)) {
>            /* Multicast all bit is set, receive all multicast frames. */
>          } else {
> -          unsigned mcast_idx = e100_compute_mcast_idx(buf);
> +          unsigned mcast_idx = (net_crc32(buf, ETH_ALEN) & BITS(7, 2)) >> 2;
>            assert(mcast_idx < 64);
>            if (s->mult[mcast_idx >> 3] & (1 << (mcast_idx & 7))) {
>              /* Multicast frame is allowed in hash table. */
>