HTTP/2: used bitwise operation to replace division and modulo.

[Ruslan Ermilov]

On Sun, Mar 04, 2018 at 10:36:43PM -0800, tokers wrote:
> # HG changeset patch
> # User Alex Zhang <zchao1995 at gmail.com>
> # Date 1520229178 -28800
> #      Mon Mar 05 13:52:58 2018 +0800
> # Node ID 03ecef37a93d541e55802393636c101a4da14550
> # Parent  265c29b0b8b8c54b1c623268481ed85324ce3c79
> HTTP/2: used bitwise operation to replace division and modulo.
> 
> Signed-off-by: Alex Zhang <zchao1995 at gmail.com>

No, thanks.

- there is no difference in assembler output even with -O0,
  with either GCC or Clang, and the author likes it the way
  it's written;

- this would require parenthesis around the & operator on
  the LHS of ==.

- the patch is incomplete.

Also, please fix your MUA so that it doesn't break patches
by wrapping lines.

> diff -r 265c29b0b8b8 -r 03ecef37a93d src/http/v2/ngx_http_v2.c
> --- a/src/http/v2/ngx_http_v2.c Thu Mar 01 11:42:55 2018 +0300
> +++ b/src/http/v2/ngx_http_v2.c Mon Mar 05 13:52:58 2018 +0800
> @@ -1094,7 +1094,7 @@
>                     "depends on %ui excl:%ui weight:%ui",
>                     h2c->state.sid, depend, excl, weight);
> 
> -    if (h2c->state.sid % 2 == 0 || h2c->state.sid <= h2c->last_sid) {
> +    if (h2c->state.sid & 0x1 == 0 || h2c->state.sid <= h2c->last_sid) {
>          ngx_log_error(NGX_LOG_INFO, h2c->connection->log, 0,
>                        "client sent HEADERS frame with incorrect identifier
> "
>                        "%ui, the last was %ui", h2c->state.sid,
> h2c->last_sid);
> diff -r 265c29b0b8b8 -r 03ecef37a93d src/http/v2/ngx_http_v2_filter_module.c
> --- a/src/http/v2/ngx_http_v2_filter_module.c   Thu Mar 01 11:42:55 2018
> +0300
> +++ b/src/http/v2/ngx_http_v2_filter_module.c   Mon Mar 05 13:52:58 2018
> +0800
> @@ -1149,8 +1149,8 @@
>      value -= prefix;
> 
>      while (value >= 128) {
> -        *pos++ = value % 128 + 128;
> -        value /= 128;
> +        *pos++ = (value & 0x7f) + 128;
> +        value >>= 7;
>      }
> 
>      *pos++ = (u_char) value;

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-- 
Ruslan Ermilov
Assume stupidity not malice