xls/modules/zstd: Add rle block decoder

Adds RleBlockDecoder responsible for decoding Blocks
of RLE_Block Block_Type as specified in RFC 8878, paragraph 3.1.1.2.2.
https://datatracker.ietf.org/doc/html/rfc8878#section-3.1.1.2.2

RleBlockDecoder communicates through BlockDataPacket channels.
It reuses existing RunLengthDecoder block which is interfaced through
two seprate procs:

 * RleDataPacker
 * BatchPacker

Which are responsible for converting input data into format accepted by
RLE decoder and for gathering RLE decoder output symbols into batches
which are then send out through BlockDataPacket.

Internal-tag: [#51473]
Signed-off-by: Pawel Czarnecki <[email protected]>

Author: lpawelcz

xls/modules/zstd/BUILD

@@ -155,3 +155,21 @@ xls_dslx_test(
     name = "raw_block_dec_dslx_test",
     library = ":raw_block_dec_dslx",
 )
+
+xls_dslx_library(
+    name = "rle_block_dec_dslx",
+    srcs = [
+        "rle_block_dec.x",
+    ],
+    deps = [
+        ":buffer_dslx",
+        ":common_dslx",
+        "//xls/modules/rle:rle_common_dslx",
+        "//xls/modules/rle:rle_dec_dslx",
+    ],
+)
+
+xls_dslx_test(
+    name = "rle_block_dec_dslx_test",
+    library = ":rle_block_dec_dslx",
+)

xls/modules/zstd/common.x

@@ -14,8 +14,12 @@
 
 pub const DATA_WIDTH = u32:64;
 pub const MAX_ID = u32::MAX;
+pub const SYMBOL_WIDTH = u32:8;
+pub const BLOCK_SIZE_WIDTH = u32:21;
 
 pub type BlockData = bits[DATA_WIDTH];
+pub type BlockPacketLength = u32;
+pub type BlockSize = bits[BLOCK_SIZE_WIDTH];
 
 pub enum BlockType : u2 {
     RAW = 0,
@@ -29,5 +33,5 @@ pub struct BlockDataPacket {
     last_block: bool,
     id: u32,
     data: BlockData,
-    length: u32
+    length: BlockPacketLength,
 }