compress: Improve RingBuffer usage

Author: joadnacer

lib/std/compress/zstandard.zig

@@ -34,7 +34,7 @@ pub fn DecompressStream(
         checksum: if (options.verify_checksum) ?u32 else void,
         current_frame_decompressed_size: usize,
 
-        pub const Error = ReaderType.Error || error{
+        pub const Error = ReaderType.Error || RingBuffer.Error || error{
             ChecksumFailure,
             DictionaryIdFlagUnsupported,
             MalformedBlock,
@@ -219,9 +219,7 @@ pub fn DecompressStream(
             }
 
             const size = @min(self.buffer.len(), buffer.len);
-            for (0..size) |i| {
-                buffer[i] = self.buffer.read().?;
-            }
+            try self.buffer.readFirst(buffer, size);
             if (self.state == .LastBlock and self.buffer.len() == 0) {
                 self.state = .NewFrame;
                 self.allocator.free(self.literal_fse_buffer);

lib/std/compress/zstandard/decode/block.zig

@@ -311,8 +311,8 @@ pub const DecodeState = struct {
         try self.decodeLiteralsRingBuffer(dest, sequence.literal_length);
         const copy_start = dest.write_index + dest.data.len - sequence.offset;
         const copy_slice = dest.sliceAt(copy_start, sequence.match_length);
-        for (copy_slice.first) |b| dest.writeAssumeCapacity(b);
-        for (copy_slice.second) |b| dest.writeAssumeCapacity(b);
+        dest.writeSliceAssumeCapacity(copy_slice.first);
+        dest.writeSliceAssumeCapacity(copy_slice.second);
         self.written_count += sequence.match_length;
     }
 
@@ -723,9 +723,7 @@ pub fn decodeBlockRingBuffer(
         },
         .rle => {
             if (src.len < 1) return error.MalformedRleBlock;
-            for (0..block_size) |_| {
-                dest.writeAssumeCapacity(src[0]);
-            }
+            dest.writeSliceAssumeCapacity(src[0..block_size]);
             consumed_count.* += 1;
             decode_state.written_count += block_size;
             return block_size;