modules/zstd: Add common zstd definitions

Internal-tag: [#51343]
Signed-off-by: Robert Winkler <[email protected]>

xls/modules/zstd/BUILD

@@ -83,6 +83,14 @@ xls_dslx_library(
     ],
 )
 
+xls_dslx_library(
+    name = "common_dslx",
+    srcs = [
+        "common.x",
+    ],
+    deps = [],
+)
+
 xls_dslx_test(
     name = "frame_header_dslx_test",
     library = ":frame_header_dslx",

xls/modules/zstd/common.x

@@ -0,0 +1,33 @@
+// Copyright 2023 The XLS 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
+//
+//      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.
+
+pub const DATA_WIDTH = u32:64;
+pub const MAX_ID = u32::MAX;
+
+pub type BlockData = bits[DATA_WIDTH];
+
+pub enum BlockType : u2 {
+    RAW = 0,
+    RLE = 1,
+    COMPRESSED = 2,
+    RESERVED = 3,
+}
+
+pub struct BlockDataPacket {
+    last: bool,
+    last_block: bool,
+    id: u32,
+    data: BlockData,
+    length: u32
+}