1 files changed, 91 insertions, 0 deletions
diff --git a/libs/vibrator/ExternalVibrationUtils.cpp b/libs/vibrator/ExternalVibrationUtils.cpp
new file mode 100644
index 0000000000..749c568457
--- /dev/null
+++ b/libs/vibrator/ExternalVibrationUtils.cpp
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <cstring>
+
+#include <math.h>
+
+#include <vibrator/ExternalVibrationUtils.h>
+
+namespace android::os {
+
+namespace {
+static constexpr float HAPTIC_SCALE_VERY_LOW_RATIO = 2.0f / 3.0f;
+static constexpr float HAPTIC_SCALE_LOW_RATIO = 3.0f / 4.0f;
+static constexpr float HAPTIC_MAX_AMPLITUDE_FLOAT = 1.0f;
+
+float getHapticScaleGamma(HapticScale scale) {
+    switch (scale) {
+    case HapticScale::VERY_LOW:
+        return 2.0f;
+    case HapticScale::LOW:
+        return 1.5f;
+    case HapticScale::HIGH:
+        return 0.5f;
+    case HapticScale::VERY_HIGH:
+        return 0.25f;
+    default:
+        return 1.0f;
+    }
+}
+
+float getHapticMaxAmplitudeRatio(HapticScale scale) {
+    switch (scale) {
+    case HapticScale::VERY_LOW:
+        return HAPTIC_SCALE_VERY_LOW_RATIO;
+    case HapticScale::LOW:
+        return HAPTIC_SCALE_LOW_RATIO;
+    case HapticScale::NONE:
+    case HapticScale::HIGH:
+    case HapticScale::VERY_HIGH:
+        return 1.0f;
+    default:
+        return 0.0f;
+    }
+}
+
+} // namespace
+
+bool isValidHapticScale(HapticScale scale) {
+    switch (scale) {
+    case HapticScale::MUTE:
+    case HapticScale::VERY_LOW:
+    case HapticScale::LOW:
+    case HapticScale::NONE:
+    case HapticScale::HIGH:
+    case HapticScale::VERY_HIGH:
+        return true;
+    }
+    return false;
+}
+
+void scaleHapticData(float* buffer, size_t length, HapticScale scale) {
+    if (!isValidHapticScale(scale) || scale == HapticScale::NONE) {
+        return;
+    }
+    if (scale == HapticScale::MUTE) {
+        memset(buffer, 0, length * sizeof(float));
+        return;
+    }
+    float gamma = getHapticScaleGamma(scale);
+    float maxAmplitudeRatio = getHapticMaxAmplitudeRatio(scale);
+    for (size_t i = 0; i < length; i++) {
+        float sign = buffer[i] >= 0 ? 1.0 : -1.0;
+        buffer[i] = powf(fabsf(buffer[i] / HAPTIC_MAX_AMPLITUDE_FLOAT), gamma)
+                * maxAmplitudeRatio * HAPTIC_MAX_AMPLITUDE_FLOAT * sign;
+    }
+}
+
+} // namespace android::os