Ok. I'll check your proposal on BE/LE.
-----Original Message-----
From: Ilya Maximets [mailto:i.maxim...@samsung.com]
Sent: Friday, December 11, 2015 5:54 PM
To: Grigore Ion-B17953 <ion.grig...@freescale.com>; Maxim Uvarov
<maxim.uva...@linaro.org>; lng-odp@lists.linaro.org
Subject: Re: [PATCHv6] helper : Fix UDP checksum computation
On 11.12.2015 18:47, Ion Grigore wrote:
> A more precise question. Did you check on a LE platform ?
Yes. On my LE i7.
>>>>> - /* Fold sum to 16 bits: add carrier to result */
>>>>> - while (sum >> 16)
>>>>> - sum = (sum & 0xFFFF) + (sum >> 16);
>>>>> -
>>>>> + (iph->dst_addr & 0xFFFF) + (iph->dst_addr >> 16) +
>>>>> + u8_pad_to_u16(iph->proto, 1) + udph->length;
>>>> I meant something like:
>>>>
>>>> union {
>>>> uint8_t v8[2];
>>>> uint16_t v16;
>>>> } val;
>>>>
>>>> val.v8[0] = 0;
>>>> val.v8[1] = iph->proto;
>>>>
>>>
>>> The val.val16 must be swapped on LE platforms.
>>
>> NO.
>>
>> Did you checked this ?
>
> And you?
>
>>
>>>
>>>
>>>> sum = (iph->src_addr & 0xFFFF) + (iph->src_addr >> 16) +
>>>> (iph->dst_addr & 0xFFFF) + (iph->dst_addr >> 16) +
>>>> val.v16 + udph->length;
>>>>
>>>>> + udplen = odp_be_to_cpu_16(udph->length);
>>>>> + buf = (uint16_t *)((void *)udph);
>>>>> + /* 32-bit sum of UDP header (checksum field cleared) and UDP data */
>>>>> + for ( ; udplen > 1; udplen -= 2)
>>>>> + sum += *buf++;
>>>>> + /* Length is not a multiple of 2 bytes */
>>>>> + if (udplen)
>>>>> + sum += u8_pad_to_u16(*buf, 0);
>>>> val.v8[0] = *buf;
>>>> val.v8[1] = 0;
>>>>
>>>> sum += val.v16;
>>>>
>>>> Isn't it more understandable, then artificial byte swapping?
>>>>
>>>
>>> The val.val16 must be swapped on LE platforms.
>>
>> NO.
>>
>> Did you checked this ?
>
> And you?
>
> P.S. Just to be honest, I checked this a few minutes ago.
> Helper test below works.
>
> Yes on BE/LE platforms, but not with the change you proposed.
So why you talking that val.val16 must be swapped if you do not understand how
it works and you have not tested it?
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