pw_random: Create module

Creates the pw_random module, starting it off with a random number
generator interface and an implementation based on the xorshift*
algorithm.

Change-Id: Ideda3eb9b713c586ce12230b8f572d079435d949
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/15362
Commit-Queue: Armando Montanez <amontanez@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
diff --git a/pw_random/BUILD.gn b/pw_random/BUILD.gn
new file mode 100644
index 0000000..d9dc72a
--- /dev/null
+++ b/pw_random/BUILD.gn
@@ -0,0 +1,49 @@
+# Copyright 2020 The Pigweed Authors
+#
+# 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
+#
+#     https://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.
+
+# gn-format disable
+import("//build_overrides/pigweed.gni")
+
+import("$dir_pw_build/target_types.gni")
+import("$dir_pw_docgen/docs.gni")
+import("$dir_pw_unit_test/test.gni")
+config("default_config") {
+  include_dirs = [ "public" ]
+}
+
+pw_source_set("pw_random") {
+  public_configs = [ ":default_config" ]
+  public = [
+    "public/pw_random/random.h",
+    "public/pw_random/xor_shift.h",
+  ]
+  public_deps = [
+    dir_pw_bytes,
+    dir_pw_span,
+    dir_pw_status,
+  ]
+}
+
+pw_test_group("tests") {
+  tests = [ ":xor_shift_star_test" ]
+}
+
+pw_test("xor_shift_star_test") {
+  deps = [ ":pw_random" ]
+  sources = [ "xor_shift_test.cc" ]
+}
+
+pw_doc_group("docs") {
+  sources = [ "docs.rst" ]
+}