commit 74722c3ab910921296a87596ea6d7460e1f75818
author Ian Romanick <ian.d.romanick@intel.com> Wed Oct 21 08:40:44 2020 +0300
committer Martin Peres <martin.peres@mupuf.org> Thu Oct 22 07:47:28 2020 +0300
tree 084bab5f292ec95ec2ac1127f17338a13067779d
parent 1331b86299b2404eb231b1ae1c6564de5c80e466

glx: rework __glXCalculateUsableExtensions to be more readable

We are about to make the GLX extension equation even more complex by
adding force-enable/disable. Before doing so, split the line into
multiple stages that can get a proper comment to explain what is going
on.

The code is taken mostly verbatim from Ian Romanick's comment:
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7212#note_668045

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Martin Peres <martin.peres@mupuf.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7212>

src/glx/glxextensions.c

diff --git a/src/glx/glxextensions.c b/src/glx/glxextensions.c
index d26168e..ba14487 100644
--- a/src/glx/glxextensions.c
+++ b/src/glx/glxextensions.c
@@ -695,17 +695,33 @@
 
    if (display_is_direct_capable) {
       for (i = 0; i < __GLX_EXT_BYTES; i++) {
-         usable[i] = (client_glx_support[i] & client_glx_only[i])
-            | (client_glx_support[i] & psc->direct_support[i] &
-               server_support[i])
-            | (client_glx_support[i] & psc->direct_support[i] &
-               direct_glx_only[i]);
+         /* Enable extensions that the client supports that only have a client-side
+          * component.
+          */
+         unsigned char u = client_glx_support[i] & client_glx_only[i];
+
+         /* Enable extensions that the client supports, are supported for direct
+          * rendering, and either are supported by the server or only have a
+          * direct-rendering component.
+          */
+         u |= client_glx_support[i] & psc->direct_support[i] &
+                 (server_support[i] | direct_glx_only[i]);
+
+         usable[i] = u;
+
       }
    }
    else {
       for (i = 0; i < __GLX_EXT_BYTES; i++) {
-         usable[i] = (client_glx_support[i] & client_glx_only[i])
-            | (client_glx_support[i] & server_support[i]);
+         /* Enable extensions that the client supports that only have a
+          * client-side component.
+          */
+         unsigned char u = client_glx_support[i] & client_glx_only[i];
+
+         /* Enable extensions that the client and server both support */
+         u |= client_glx_support[i] & server_support[i];
+
+         usable[i] = u;
       }
    }