code review 105290049: image/png: remove unnecessary function call

image/png: remove unnecessary function call

paeth(0, x, 0) == x for any uint8 value.

[ruiu, 2014-06-21 02:22:55]

Hello golang-codereviews@googlegroups.com,

I'd like you to review this change to
https://code.google.com/p/go

[bradfitz, 2014-06-21 16:31:28]

R=nigeltao



On Fri, Jun 20, 2014 at 7:22 PM, ruiu via golang-codereviews <
golang-codereviews@googlegroups.com> wrote:

> Reviewers: golang-codereviews,
>
> Message:
> Hello golang-codereviews@googlegroups.com,
>
> I'd like you to review this change to
> https://code.google.com/p/go
>
>
> Description:
> image/png: remove unnecessary function call
>
> paeth(0, x, 0) = x for any x.
>
> Please review this at https://codereview.appspot.com/105290049/
>
> Affected files (+1, -1 lines):
>   M src/pkg/image/png/writer.go
>
>
> Index: src/pkg/image/png/writer.go
> ===================================================================
> --- a/src/pkg/image/png/writer.go
> +++ b/src/pkg/image/png/writer.go
> @@ -188,7 +188,7 @@
>         // The Paeth filter.
>         sum = 0
>         for i := 0; i < bpp; i++ {
> -               cdat4[i] = cdat0[i] - paeth(0, pdat[i], 0)
> +               cdat4[i] = cdat0[i] - pdat[i]
>                 sum += abs8(cdat4[i])
>         }
>         for i := bpp; i < n; i++ {
>
>
> --
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[ruiu, 2014-06-21 17:44:48]

I verified that paeth(0, x, 0) == x for all possible uint8 values by
writing a test, just in case.


On Sat, Jun 21, 2014 at 9:31 AM, Brad Fitzpatrick <bradfitz@golang.org>
wrote:

> R=nigeltao
>
>
>
> On Fri, Jun 20, 2014 at 7:22 PM, ruiu via golang-codereviews <
> golang-codereviews@googlegroups.com> wrote:
>
>> Reviewers: golang-codereviews,
>>
>> Message:
>> Hello golang-codereviews@googlegroups.com,
>>
>> I'd like you to review this change to
>> https://code.google.com/p/go
>>
>>
>> Description:
>> image/png: remove unnecessary function call
>>
>> paeth(0, x, 0) = x for any x.
>>
>> Please review this at https://codereview.appspot.com/105290049/
>>
>> Affected files (+1, -1 lines):
>>   M src/pkg/image/png/writer.go
>>
>>
>> Index: src/pkg/image/png/writer.go
>> ===================================================================
>> --- a/src/pkg/image/png/writer.go
>> +++ b/src/pkg/image/png/writer.go
>> @@ -188,7 +188,7 @@
>>         // The Paeth filter.
>>         sum = 0
>>         for i := 0; i < bpp; i++ {
>> -               cdat4[i] = cdat0[i] - paeth(0, pdat[i], 0)
>> +               cdat4[i] = cdat0[i] - pdat[i]
>>                 sum += abs8(cdat4[i])
>>         }
>>         for i := bpp; i < n; i++ {
>>
>>
>>
>> --
>> You received this message because you are subscribed to the Google Groups
>> "golang-codereviews" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to golang-codereviews+unsubscribe@googlegroups.com.
>> For more options, visit https://groups.google.com/d/optout.
>>
>
>

[nigeltao, 2014-06-23 00:29:34]

LGTM.

[nigeltao, 2014-06-23 00:30:06]

*** Submitted as https://code.google.com/p/go/source/detail?r=d628e9e34434 ***

image/png: remove unnecessary function call

paeth(0, x, 0) == x for any uint8 value.

LGTM=nigeltao
R=golang-codereviews, bradfitz, nigeltao
CC=golang-codereviews
https://codereview.appspot.com/105290049

Committer: Nigel Tao <nigeltao@golang.org>

[gobot, 2014-06-23 01:32:07]

This CL appears to have broken the plan9-386-cnielsen builder.
See http://build.golang.org/log/7741353b19e1fbb83310d1f02781cde345fb039b