Add a simple object pool allocator

src/include/sof/objpool.h

@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright(c) 2025 Intel Corporation.
+ */
+
+#ifndef __ZEPHYR_OBJPOOL_H__
+#define __ZEPHYR_OBJPOOL_H__
+
+struct list_item;
+/**
+ * Allocate memory tracked as part of an object pool.
+ *
+ * @param head Pointer to the object pool list head.
+ * @param size Size in bytes of memory blocks to allocate.
+ *
+ * @return a pointer to the allocated memory on success, NULL on failure.
+ *
+ * Allocate a memory block of @a size bytes. @a size is used upon the first
+ * invocation to allocate memory on the heap, all consequent allocations with
+ * the same @a head must use the same @a size value. First allocation with an
+ * empty @a head allocates 2 blocks. After both blocks are taken and a third one
+ * is requested, the next call allocates 4 blocks, then 8, 16 and 32. After that
+ * 32 blocks are allocated every time. Note, that by design allocated blocks are
+ * never freed. See more below.
+ */
+void *objpool_alloc(struct list_item *head, size_t size);
+
+/**
+ * Return a block to the object pool
+ *
+ * @param head Pointer to the object pool list head.
+ * @param data Pointer to the object to return (can be NULL)
+ *
+ * @return 0 on success or a negative error code.
+ *
+ * Return a block to the object pool. Memory is never freed by design, unused
+ * blocks are kept in the object pool for future re-use.
+ */
+int objpool_free(struct list_item *head, void *data);
+
+#endif

src/lib/CMakeLists.txt

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
-set(common_files notifier.c dma.c dai.c)
+set(common_files notifier.c dma.c dai.c objpool.c)
 
 if(CONFIG_LIBRARY)
   add_local_sources(sof

src/lib/objpool.c

@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: BSD-3-Clause
+//
+// Copyright(c) 2025 Intel Corporation.
+
+#include <rtos/alloc.h>
+#include <rtos/bit.h>
+#include <sof/objpool.h>
+#include <sof/common.h>
+#include <sof/list.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+struct objpool {
+	struct list_item list;
+	unsigned int n;
+	uint32_t mask;
+	size_t size;
+	uint8_t data[];
+};
+
+#define OBJPOOL_BITS (sizeof(((struct objpool *)0)->mask) * 8)
+
+static int objpool_add(struct list_item *head, unsigned int n, size_t size)
+{
+	if (n > OBJPOOL_BITS)
+		return -ENOMEM;
+
+	if (!is_power_of_2(n))
+		return -EINVAL;
+
+	size_t aligned_size = ALIGN_UP(size, sizeof(int));
+
+	/* Initialize with 0 to give caller a chance to identify new allocations */
+	struct objpool *pobjpool = rzalloc(0, n * aligned_size + sizeof(*pobjpool));
+
+	if (!pobjpool)
+		return -ENOMEM;
+
+	pobjpool->n = n;
+	/* clear bit means free */
+	pobjpool->mask = 0;
+	pobjpool->size = size;
+
+	list_item_append(&pobjpool->list, head);
+
+	return 0;
+}
+
+void *objpool_alloc(struct list_item *head, size_t size)
+{
+	size_t aligned_size = ALIGN_UP(size, sizeof(int));
+	struct list_item *list;
+	struct objpool *pobjpool;
+
+	/* Make sure size * 32 still fits in OBJPOOL_BITS bits */
+	if (!size || aligned_size > (UINT_MAX >> 5) - sizeof(*pobjpool))
+		return NULL;
+
+	list_for_item(list, head) {
+		pobjpool = container_of(list, struct objpool, list);
+
+		uint32_t free_mask = MASK(pobjpool->n - 1, 0) & ~pobjpool->mask;
+
+		/* sanity check */
+		if (size != pobjpool->size)
+			return NULL;
+
+		if (!free_mask)
+			continue;
+
+		/* Find first free - guaranteed valid now */
+		unsigned int bit = ffs(free_mask) - 1;
+
+		pobjpool->mask |= BIT(bit);
+
+		return pobjpool->data + aligned_size * bit;
+	}
+
+	/* no free elements found */
+	unsigned int new_n;
+
+	if (list_is_empty(head)) {
+		new_n = 2;
+	} else {
+		/* Check the last one */
+		pobjpool = container_of(head->prev, struct objpool, list);
+
+		if (pobjpool->n == OBJPOOL_BITS)
+			new_n = OBJPOOL_BITS;
+		else
+			new_n = pobjpool->n << 1;
+	}
+
+	if (objpool_add(head, new_n, size) < 0)
+		return NULL;
+
+	/* Return the first element of the new objpool, which is now the last one in the list */
+	pobjpool = container_of(head->prev, struct objpool, list);
+	pobjpool->mask = 1;
+
+	return pobjpool->data;
+}
+
+int objpool_free(struct list_item *head, void *data)
+{
+	struct list_item *list;
+	struct objpool *pobjpool;
+
+	if (!data)
+		return 0;
+
+	list_for_item(list, head) {
+		pobjpool = container_of(list, struct objpool, list);
+
+		size_t aligned_size = ALIGN_UP(pobjpool->size, sizeof(int));
+
+		if ((uint8_t *)data >= pobjpool->data &&
+		    (uint8_t *)data < pobjpool->data + aligned_size * pobjpool->n) {
+			unsigned int n = ((uint8_t *)data - pobjpool->data) / aligned_size;
+
+			if ((uint8_t *)data != pobjpool->data + n * aligned_size)
+				return -EINVAL;
+
+			pobjpool->mask &= ~BIT(n);
+
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}

test/ztest/unit/fast-get/prj.conf

@@ -1,2 +1,2 @@
 CONFIG_ZTEST=y
-CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n
+CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n

test/ztest/unit/list/prj.conf

@@ -1,2 +1,2 @@
 CONFIG_ZTEST=y
-CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n
+CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n

test/ztest/unit/math/basic/arithmetic/prj.conf

@@ -1,2 +1,2 @@
 CONFIG_ZTEST=y
-CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n
+CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n

test/ztest/unit/math/basic/trigonometry/prj.conf

@@ -1,2 +1,2 @@
 CONFIG_ZTEST=y
-CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n
+CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n

test/ztest/unit/objpool/CMakeLists.txt

@@ -0,0 +1,30 @@
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(test_objpool)
+
+set(SOF_ROOT "${PROJECT_SOURCE_DIR}/../../../..")
+
+# Include SOF CMake functions
+include(${SOF_ROOT}/scripts/cmake/misc.cmake)
+
+target_include_directories(app PRIVATE
+	${SOF_ROOT}/zephyr/include
+	${SOF_ROOT}/src/include
+	${SOF_ROOT}/src/platform/posix/include
+)
+
+# Define SOF-specific configurations for unit testing
+target_compile_definitions(app PRIVATE
+	-DCONFIG_ZEPHYR_POSIX=1
+)
+
+target_sources(app PRIVATE
+	test_objpool_ztest.c
+	${SOF_ROOT}/src/lib/objpool.c
+)
+
+target_link_libraries(app PRIVATE "-Wl,--wrap=rzalloc")
+
+# Add RELATIVE_FILE definitions for SOF trace functionality
+sof_append_relative_path_definitions(app)

test/ztest/unit/objpool/prj.conf

@@ -0,0 +1,2 @@
+CONFIG_ZTEST=y
+CONFIG_SOF_FULL_ZEPHYR_APPLICATION=n

test/ztest/unit/objpool/test_objpool_ztest.c

@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: BSD-3-Clause
+//
+// Copyright(c) 2025 Intel Corporation.
+
+#define DATA_SIZE 5
+#define ALIGNED_SIZE ALIGN_UP(DATA_SIZE, sizeof(int))
+
+#include <zephyr/ztest.h>
+#include <sof/objpool.h>
+#include <sof/common.h>
+#include <sof/list.h>
+#include <stdlib.h>
+#include <string.h>
+
+void *__wrap_rzalloc(uint32_t flags, size_t bytes)
+{
+	(void)flags;
+
+	void *ret = malloc(bytes);
+
+	if (ret)
+		memset(ret, 0, bytes);
+
+	return ret;
+}
+
+ZTEST(objpool_suite, test_objpool_wrong_size)
+{
+	struct list_item head = LIST_INIT(head);
+	/* new object pool of 2 blocks */
+	uint8_t *block1 = objpool_alloc(&head, DATA_SIZE);
+	/* should fail because of a different size */
+	uint8_t *block2 = objpool_alloc(&head, DATA_SIZE + 1);
+	/* second block in the first object pool */
+	uint8_t *block3 = objpool_alloc(&head, DATA_SIZE);
+	/* new object pool of 4 blocks */
+	uint8_t *block4 = objpool_alloc(&head, DATA_SIZE);
+	/* should fail because of a different size */
+	uint8_t *block5 = objpool_alloc(&head, DATA_SIZE * 2);
+
+	zassert_not_null(block1);
+	zassert_is_null(block2);
+	zassert_not_null(block3);
+	zassert_not_null(block4);
+	zassert_is_null(block5);
+
+	zassert_not_ok(objpool_free(&head, block1 + 1));
+	zassert_ok(objpool_free(&head, block1));
+	zassert_not_ok(objpool_free(&head, block3 + 1));
+	zassert_ok(objpool_free(&head, block3));
+	zassert_not_ok(objpool_free(&head, block4 + 1));
+	zassert_ok(objpool_free(&head, block4));
+}
+
+ZTEST(objpool_suite, test_objpool)
+{
+	struct list_item head = LIST_INIT(head);
+	void *blocks[62]; /* 2 + 4 + 8 + 16 + 32 */
+	unsigned int k = 0;
+
+	/* Loop over all powers: 2^1..2^5 */
+	for (unsigned int i = 1; i <= 5; i++) {
+		unsigned int n = 1 << i;
+		uint8_t *start;
+
+		for (unsigned int j = 0; j < n; j++) {
+			uint8_t *block = objpool_alloc(&head, DATA_SIZE);
+
+			zassert_not_null(block, "allocation failed loop %u iter %u", i, j);
+
+			if (!j)
+				start = block;
+			else
+				zassert_equal(block, start + ALIGNED_SIZE * j, "wrong pointer");
+
+			blocks[k++] = block;
+		}
+	}
+
+	while (k--)
+		zassert_ok(objpool_free(&head, blocks[k]), "free failed");
+}
+
+ZTEST_SUITE(objpool_suite, NULL, NULL, NULL, NULL, NULL);

test/ztest/unit/objpool/testcase.yaml

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: BSD-3-Clause
+#
+# Copyright(c) 2025 Intel Corporation.
+#
+# Object pool allocator unit tests for Ztest framework
+
+tests:
+  sof.objpool:
+    tags: unit
+    platform_allow: native_sim
+    integration_platforms:
+      - native_sim
+    build_only: false