Import of the watch repository from Pebble

src/fw/util/ratio.h

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <inttypes.h>
+
+// ratio32 - uint32 as a real number between 0 and 1
+
+#define RATIO32_MIN 0
+#define RATIO32_MAX 65535
+
+static inline uint32_t ratio32_mul(uint32_t a, uint32_t b) {
+  return (a * b) / RATIO32_MAX;
+}
+
+static inline uint32_t ratio32_div(uint32_t a, uint32_t b) {
+  return (a * RATIO32_MAX) / b;
+}
+
+//! Converts a ratio32 to a percent in the range [0, 100]
+static inline uint32_t ratio32_to_percent(uint32_t ratio) {
+  return (ratio * 100) / RATIO32_MAX;
+}
+
+//! Converts a percent in the range [0, 100] to a ratio32
+static inline uint32_t ratio32_from_percent(uint32_t percent) {
+  return (percent * RATIO32_MAX) / 100 + 1;
+}