Select the audio/video backend with the best match of caps

Author: crashfort

src/svr_common/svr_common.cpp

@@ -7,6 +7,7 @@
 #include <assert.h>
 #include <mfapi.h>
 #include <strsafe.h>
+#include <intrin.h>
 
 // Prefer to use this instead of calling Release yourself since you can use this to see the actual reference count.
 void svr_release(struct IUnknown* p)
@@ -442,6 +443,12 @@ s32 svr_count_num_true(bool* opts, s32 num)
     return ret;
 }
 
+s32 svr_count_set_bits(u32 bits)
+{
+    s32 ret = __popcnt(bits);
+    return ret;
+}
+
 bool svr_does_file_exist(const char* path)
 {
     WIN32_FILE_ATTRIBUTE_DATA attr;

src/svr_common/svr_common.h

@@ -186,6 +186,7 @@ s64 svr_rescale(s64 a, s64 b, s64 c);
 bool svr_check_all_true(bool* opts, s32 num);
 bool svr_check_one_true(bool* opts, s32 num);
 s32 svr_count_num_true(bool* opts, s32 num);
+s32 svr_count_set_bits(u32 bits);
 
 bool svr_does_file_exist(const char* path);
 

src/svr_standalone/game_audio.cpp

@@ -15,17 +15,24 @@ GameAudioSearch GAME_AUDIO_BACKENDS[] =
 
 void game_audio_init()
 {
+    GameAudioDesc* best_desc = NULL;
+    s32 best_match = 0;
+
     for (s32 i = 0; i < SVR_ARRAY_SIZE(GAME_AUDIO_BACKENDS); i++)
     {
         GameAudioSearch* s = &GAME_AUDIO_BACKENDS[i];
 
-        if (game_state.search_desc.caps & s->caps)
+        s32 num_match = svr_count_set_bits(game_state.search_desc.caps & s->caps);
+
+        if (num_match > best_match)
         {
-            game_state.audio_desc = s->desc;
-            break;
+            best_desc = s->desc;
+            best_match = num_match;
         }
     }
 
+    game_state.audio_desc = best_desc;
+
     if (game_state.audio_desc)
     {
         svr_log("Using game audio backend %s\n", game_state.audio_desc->name);

src/svr_standalone/game_video.cpp

@@ -14,17 +14,24 @@ GameVideoSearch GAME_VIDEO_BACKENDS[] =
 // Find the right video backend from the search description.
 void game_video_init()
 {
+    GameVideoDesc* best_desc = NULL;
+    s32 best_match = 0;
+
     for (s32 i = 0; i < SVR_ARRAY_SIZE(GAME_VIDEO_BACKENDS); i++)
     {
         GameVideoSearch* s = &GAME_VIDEO_BACKENDS[i];
 
-        if (game_state.search_desc.caps & s->caps)
+        s32 num_match = svr_count_set_bits(game_state.search_desc.caps & s->caps);
+
+        if (num_match > best_match)
         {
-            game_state.video_desc = s->desc;
-            break;
+            best_desc = s->desc;
+            best_match = num_match;
         }
     }
 
+    game_state.video_desc = best_desc;
+
     if (game_state.video_desc == NULL)
     {
         game_init_error("No video backend available.");