zephyr: samples: add basic sample from main Zephyr repo

Zephyr upstream repo is not pulling in lz4 as a module anymore and will
stop maintaining this code sample. As it's useful for testing lz4 in
the context of a working Zephyr application, add it here.

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

Author: kartben

zephyr/samples/lorem_ipsum/CMakeLists.txt

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(lz4)
+
+target_sources(app PRIVATE src/main.c)

zephyr/samples/lorem_ipsum/README.rst

@@ -0,0 +1,15 @@
+Overview
+********
+
+A simple sample that can be used with any Zephyr supported board and
+compress & decompress the user data to the console.
+
+Building and Running
+********************
+
+The sample can be built and executed on nrf52840dk/nrf52840 as follows::
+
+    west build -b nrf52840dk/nrf52840 zephyr/samples/lorem_ipsum
+    west flash
+
+To build for another board, change "nrf52840dk/nrf52840" above to that board's name.

zephyr/samples/lorem_ipsum/prj.conf

@@ -0,0 +1,4 @@
+CONFIG_LZ4=y
+CONFIG_REQUIRES_FULL_LIBC=y
+CONFIG_HEAP_MEM_POOL_SIZE=16384
+CONFIG_COMMON_LIBC_MALLOC_ARENA_SIZE=24576

zephyr/samples/lorem_ipsum/sample.yaml

@@ -0,0 +1,24 @@
+sample:
+  name: lz4 sample
+  description: lz4 data compression library
+common:
+  tags:
+    - compression
+    - lz4
+  min_ram: 64
+  filter: CONFIG_FULL_LIBC_SUPPORTED
+  harness: console
+  harness_config:
+    type: one_line
+    regex:
+      - "Validation done. (.*)"
+  modules:
+    - lz4
+tests:
+  sample.compression.lz4:
+    integration_platforms:
+      - mps2/an385
+      - qemu_riscv64
+    tags:
+      - compression
+      - lz4

zephyr/samples/lorem_ipsum/src/main.c

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2020 Linumiz
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+#include <zephyr/kernel.h>
+#include <zephyr/misc/lorem_ipsum.h>
+#include <string.h>
+#include <stdlib.h>
+#include "lz4.h"
+
+int main(void)
+{
+	static const char *src = LOREM_IPSUM;
+
+	const int src_size = (int)(strlen(src) + 1);
+	const int max_dst_size = LZ4_compressBound(src_size);
+
+	char *compressed_data = malloc((size_t)max_dst_size);
+
+	if (compressed_data == NULL) {
+		printk("Failed to allocate memory for compressed data\n");
+		return 0;
+	}
+
+	const int compressed_data_size = LZ4_compress_default(src,
+					compressed_data, src_size,
+					max_dst_size);
+	if (compressed_data_size <= 0) {
+		printk("Failed to compress the data\n");
+		return 0;
+	}
+
+	printk("Original Data size: %d\n", src_size);
+	printk("Compressed Data size : %d\n", compressed_data_size);
+
+	compressed_data = (char *)realloc(compressed_data,
+					  (size_t)compressed_data_size);
+	if (compressed_data == NULL) {
+		printk("Failed to re-alloc memory for compressed data\n");
+		return 0;
+	}
+
+	char * const decompressed_data = malloc(src_size);
+
+	if (decompressed_data == NULL) {
+		printk("Failed to allocate memory to decompress data\n");
+		return 0;
+	}
+
+	const int decompressed_size = LZ4_decompress_safe(compressed_data,
+				      decompressed_data, compressed_data_size,
+				      src_size);
+	if (decompressed_size < 0) {
+		printk("Failed to decompress the data\n");
+		return 0;
+	}
+
+	free(compressed_data);
+
+	if (decompressed_size >= 0) {
+		printk("Successfully decompressed some data\n");
+	}
+
+	if (decompressed_size != src_size) {
+		printk("Decompressed data is different from original\n");
+		return 0;
+	}
+
+	if (memcmp(src, decompressed_data, src_size) != 0) {
+		printk("Validation failed.\n");
+		printk("*src and *new_src are not identical\n");
+		return 0;
+	}
+
+	printk("Validation done. The string we ended up with is:\n%s\n",
+			decompressed_data);
+	return 0;
+}