Import of the watch repository from Pebble

src/fw/util/stringlist.h

@@ -0,0 +1,56 @@
+/*
+ * 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 <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+//! A string list is a serialized array of NULL terminated strings
+//! It is used to pass groups of strings as a single attribute on the wire.
+//! E.g. canned responses for notifications
+//! @note the serialized_byte_length does not include the last terminated byte
+
+//! Calculate the maximum string list size given the number of values and their max length
+#define StringListSize(num_values, max_value_size) \
+    (sizeof(StringList) + ((num_values) * (max_value_size)))
+
+typedef struct {
+  uint16_t serialized_byte_length;
+  char data[];
+} StringList;
+
+//! Retrieve a string from a string list
+//! @param list a pointer to the string list
+//! @param index of the desired string
+//! @note string lists are zero indexed
+//! @return a pointer to the start of the string, NULL if index out of bounds
+char *string_list_get_at(StringList *list, size_t index);
+
+//! Count the number of strings in a string list
+//! @param list a pointer to the string list
+//! @return the number of strings in a list
+size_t string_list_count(StringList *list);
+
+//! Adds a string to a string list
+//! @param list a pointer to the string list
+//! @param max_list_size the max size of the list (includes the header and last terminated byte)
+//! @param str the string to add
+//! @param max_str_size the string to add
+//! @return the number of bytes written not including the null terminator
+int string_list_add_string(StringList *list, size_t max_list_size, const char *str,
+                           size_t max_str_size);