Import of the watch repository from Pebble

src/fw/kernel/util/segment.h

@@ -0,0 +1,59 @@
+/*
+ * 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.
+ */
+
+//! Memory Segments
+//!
+//! A memory segment is a representation of a contiguous chunk of memory.
+//! Memory segments can be split, dividing the segment in two. This API
+//! is designed to simplify tasks such as process loading where a chunk
+//! of memory must be allocated into a bunch of smaller chunks of
+//! various fixed and dynamic sizes.
+
+#pragma once
+
+#include <stddef.h>
+
+
+typedef struct MemorySegment {
+  void *start;  //!< The lowest address of the segment
+  void *end;    //!< One past the highest address of the segment
+} MemorySegment;
+
+
+//! Returns the size of the largest object that the segment can contain.
+size_t memory_segment_get_size(MemorySegment *segment);
+
+//! Align the start pointer of a segment such that it is suitably
+//! aligned for any object.
+void memory_segment_align(MemorySegment *segment);
+
+//! Split a memory segment into two.
+//!
+//! The child memory segment is allocated from the start of the parent,
+//! and the start of the parent is moved to the end of the child.
+//!
+//! After the split, the start addresses of both the parent and the
+//! child are guaranteed to be suitably aligned for any object.
+//!
+//! @param parent the memory segment to split.
+//! @param child the memory segment created from the split. May be NULL.
+//! @param size size of the new memory segment.
+//!
+//! @return start of child memory segment if successful, or NULL if
+//!         there is not enough space in the parent segment to split
+//!         with the requested size.
+void * memory_segment_split(MemorySegment * restrict parent,
+                            MemorySegment * restrict child, size_t size);