Audio: Fixes for FCC_LIMIT validation

Test: SoundPool(Aac|Haptic|Midi|Ogg)Test
Test: AudioEffectTest, AudioPreProcessingTest
Test: BassBoostTest, EnvReverbTest, EqualizerTest, LoudnessEnhancerTest
Test: PresetReverbTest, VirtualizerTest, VisualizerTest
Bug: 189325443
Change-Id: I0ce958a2e111d8f55391a00fafbc95135bee288e
diff --git a/media/libaudioprocessing/AudioMixerBase.cpp b/media/libaudioprocessing/AudioMixerBase.cpp
index a54e22f..f30eb54 100644
--- a/media/libaudioprocessing/AudioMixerBase.cpp
+++ b/media/libaudioprocessing/AudioMixerBase.cpp
@@ -18,6 +18,7 @@
 #define LOG_TAG "AudioMixer"
 //#define LOG_NDEBUG 0
 
+#include <array>
 #include <sstream>
 #include <string.h>
 
@@ -1295,8 +1296,29 @@
 
 // Needs to derive a compile time constant (constexpr).  Could be targeted to go
 // to a MONOVOL mixtype based on MAX_NUM_VOLUMES, but that's an unnecessary complication.
-#define MIXTYPE_MONOVOL(mixtype) ((mixtype) == MIXTYPE_MULTI ? MIXTYPE_MULTI_MONOVOL : \
-        (mixtype) == MIXTYPE_MULTI_SAVEONLY ? MIXTYPE_MULTI_SAVEONLY_MONOVOL : (mixtype))
+
+constexpr int MIXTYPE_MONOVOL(int mixtype, int channels) {
+    if (channels <= FCC_2) {
+        return mixtype;
+    } else if (mixtype == MIXTYPE_MULTI) {
+        return MIXTYPE_MULTI_MONOVOL;
+    } else if (mixtype == MIXTYPE_MULTI_SAVEONLY) {
+        return MIXTYPE_MULTI_SAVEONLY_MONOVOL;
+    } else {
+        return mixtype;
+    }
+}
+
+// Helper to make a functional array from volumeRampMulti.
+template <int MIXTYPE, typename TO, typename TI, typename TV, typename TA, typename TAV,
+          std::size_t ... Is>
+static constexpr auto makeVRMArray(std::index_sequence<Is...>)
+{
+    using F = void(*)(TO*, size_t, const TI*, TA*, TV*, const TV*, TAV*, TAV);
+    return std::array<F, sizeof...(Is)>{
+            { &volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE, Is + 1), Is + 1, TO, TI, TV, TA, TAV> ...}
+        };
+}
 
 /* MIXTYPE     (see AudioMixerOps.h MIXTYPE_* enumeration)
  * TO: int32_t (Q4.27) or float
@@ -1308,40 +1330,26 @@
 static void volumeRampMulti(uint32_t channels, TO* out, size_t frameCount,
         const TI* in, TA* aux, TV *vol, const TV *volinc, TAV *vola, TAV volainc)
 {
-    switch (channels) {
-    case 1:
-        volumeRampMulti<MIXTYPE, 1>(out, frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 2:
-        volumeRampMulti<MIXTYPE, 2>(out, frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 3:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 3>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 4:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 4>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 5:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 5>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 6:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 6>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 7:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 7>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
-    case 8:
-        volumeRampMulti<MIXTYPE_MONOVOL(MIXTYPE), 8>(out,
-                frameCount, in, aux, vol, volinc, vola, volainc);
-        break;
+    static constexpr auto volumeRampMultiArray =
+            makeVRMArray<MIXTYPE, TO, TI, TV, TA, TAV>(std::make_index_sequence<FCC_LIMIT>());
+    if (channels > 0 && channels <= volumeRampMultiArray.size()) {
+        volumeRampMultiArray[channels - 1](out, frameCount, in, aux, vol, volinc, vola, volainc);
+    } else {
+        ALOGE("%s: invalid channel count:%d", __func__, channels);
     }
 }
 
+// Helper to make a functional array from volumeMulti.
+template <int MIXTYPE, typename TO, typename TI, typename TV, typename TA, typename TAV,
+          std::size_t ... Is>
+static constexpr auto makeVMArray(std::index_sequence<Is...>)
+{
+    using F = void(*)(TO*, size_t, const TI*, TA*, const TV*, TAV);
+    return std::array<F, sizeof...(Is)>{
+            { &volumeMulti<MIXTYPE_MONOVOL(MIXTYPE, Is + 1), Is + 1, TO, TI, TV, TA, TAV> ... }
+        };
+}
+
 /* MIXTYPE     (see AudioMixerOps.h MIXTYPE_* enumeration)
  * TO: int32_t (Q4.27) or float
  * TI: int32_t (Q4.27) or int16_t (Q0.15) or float
@@ -1352,31 +1360,12 @@
 static void volumeMulti(uint32_t channels, TO* out, size_t frameCount,
         const TI* in, TA* aux, const TV *vol, TAV vola)
 {
-    switch (channels) {
-    case 1:
-        volumeMulti<MIXTYPE, 1>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 2:
-        volumeMulti<MIXTYPE, 2>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 3:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 3>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 4:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 4>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 5:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 5>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 6:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 6>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 7:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 7>(out, frameCount, in, aux, vol, vola);
-        break;
-    case 8:
-        volumeMulti<MIXTYPE_MONOVOL(MIXTYPE), 8>(out, frameCount, in, aux, vol, vola);
-        break;
+    static constexpr auto volumeMultiArray =
+            makeVMArray<MIXTYPE, TO, TI, TV, TA, TAV>(std::make_index_sequence<FCC_LIMIT>());
+    if (channels > 0 && channels <= volumeMultiArray.size()) {
+        volumeMultiArray[channels - 1](out, frameCount, in, aux, vol, vola);
+    } else {
+        ALOGE("%s: invalid channel count:%d", __func__, channels);
     }
 }