This provides a standard ethernet CRC32 little-endian implementation.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 include/net/net.h |  2 ++
 net/net.c         | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/net/net.h b/include/net/net.h
index 586098cb94..4afac1a9dd 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -228,7 +228,9 @@ NetClientState *net_hub_port_find(int hub_id);
 void qdev_set_nic_properties(DeviceState *dev, NICInfo *nd);
 
 #define POLYNOMIAL_BE 0x04c11db6
+#define POLYNOMIAL_LE 0xedb88320
 uint32_t net_crc32(const uint8_t *p, int len);
+uint32_t net_crc32_le(const uint8_t *p, int len);
 unsigned compute_mcast_idx(const uint8_t *ep);
 
 #define vmstate_offset_macaddr(_state, _field)                       \
diff --git a/net/net.c b/net/net.c
index 02a567c18f..38008fe8e7 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1603,6 +1603,28 @@ uint32_t net_crc32(const uint8_t *p, int len)
     return crc;
 }
 
+uint32_t net_crc32_le(const uint8_t *p, int len)
+{
+    uint32_t crc;
+    int carry, i, j;
+    uint8_t b;
+
+    crc = 0xffffffff;
+    for (i = 0; i < len; i++) {
+        b = *p++;
+        for (j = 0; j < 8; j++) {
+            carry = (crc & 0x1) ^ (b & 0x01);
+            crc >>= 1;
+            b >>= 1;
+            if (carry) {
+                crc = crc ^ POLYNOMIAL_LE;
+            }
+        }
+    }
+
+    return crc;
+}
+
 unsigned compute_mcast_idx(const uint8_t *ep)
 {
     return net_crc32(ep, 6) >> 26;
-- 
2.11.0

On 12/05/2017 02:17 AM, Mark Cave-Ayland wrote:
> This provides a standard ethernet CRC32 little-endian implementation.
> 
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> ---
>  include/net/net.h |  2 ++
>  net/net.c         | 22 ++++++++++++++++++++++
>  2 files changed, 24 insertions(+)

Reviewed-by: Eric Blake <eblake@redhat.com>

> +            if (carry) {
> +                crc = crc ^ POLYNOMIAL_LE;
> +            }

Worth writing as 'crc ^= POLYNOMIAL_LE;'?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

On 05/12/17 14:31, Eric Blake wrote:

> On 12/05/2017 02:17 AM, Mark Cave-Ayland wrote:
>> This provides a standard ethernet CRC32 little-endian implementation.
>>
>> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>> ---
>>   include/net/net.h |  2 ++
>>   net/net.c         | 22 ++++++++++++++++++++++
>>   2 files changed, 24 insertions(+)
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 
>> +            if (carry) {
>> +                crc = crc ^ POLYNOMIAL_LE;
>> +            }
> 
> Worth writing as 'crc ^= POLYNOMIAL_LE;'?

Yes, works for me.


ATB,

Mark.

On 12/05/2017 05:17 AM, Mark Cave-Ayland wrote:
> This provides a standard ethernet CRC32 little-endian implementation.
> 
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

> ---
>  include/net/net.h |  2 ++
>  net/net.c         | 22 ++++++++++++++++++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/include/net/net.h b/include/net/net.h
> index 586098cb94..4afac1a9dd 100644
> --- a/include/net/net.h
> +++ b/include/net/net.h
> @@ -228,7 +228,9 @@ NetClientState *net_hub_port_find(int hub_id);
>  void qdev_set_nic_properties(DeviceState *dev, NICInfo *nd);
>  
>  #define POLYNOMIAL_BE 0x04c11db6
> +#define POLYNOMIAL_LE 0xedb88320
>  uint32_t net_crc32(const uint8_t *p, int len);
> +uint32_t net_crc32_le(const uint8_t *p, int len);
>  unsigned compute_mcast_idx(const uint8_t *ep);
>  
>  #define vmstate_offset_macaddr(_state, _field)                       \
> diff --git a/net/net.c b/net/net.c
> index 02a567c18f..38008fe8e7 100644
> --- a/net/net.c
> +++ b/net/net.c
> @@ -1603,6 +1603,28 @@ uint32_t net_crc32(const uint8_t *p, int len)
>      return crc;
>  }
>  
> +uint32_t net_crc32_le(const uint8_t *p, int len)
> +{
> +    uint32_t crc;
> +    int carry, i, j;
> +    uint8_t b;
> +
> +    crc = 0xffffffff;
> +    for (i = 0; i < len; i++) {
> +        b = *p++;
> +        for (j = 0; j < 8; j++) {
> +            carry = (crc & 0x1) ^ (b & 0x01);
> +            crc >>= 1;
> +            b >>= 1;
> +            if (carry) {
> +                crc = crc ^ POLYNOMIAL_LE;
> +            }
> +        }
> +    }
> +
> +    return crc;
> +}
> +
>  unsigned compute_mcast_idx(const uint8_t *ep)
>  {
>      return net_crc32(ep, 6) >> 26;
>