Probably should name the custom packages specially

1 files changed, 64 insertions, 0 deletions

diff --git a/internal/flatex/decompress_bytes.go b/internal/flatex/decompress_bytes.go
new file mode 100644
index 00000000..5a660b0a
--- /dev/null
+++ b/internal/flatex/decompress_bytes.go
@@ -0,0 +1,64 @@
+package flatex
+
+import (
+	"io"
+	"sync"
+
+	"git.sr.ht/~runxiyu/furgit/internal/bufpool"
+)
+
+// bufferDecompressor wraps the custom slice inflater so byte-slice
+// decompressions avoid repeated allocations.
+type bufferDecompressor struct {
+	inflater sliceInflater
+}
+
+var bufferDecompressorPool = sync.Pool{
+	New: func() any {
+		fixedHuffmanDecoderInit()
+		d := &bufferDecompressor{}
+		d.inflater.bits = new([maxNumLit + maxNumDist]int)
+		d.inflater.codebits = new([numCodes]int)
+		return d
+	},
+}
+
+// Decompress inflates the provided DEFLATE stream and returns the full output
+// in a pooled bufpool.Buffer along with the number of consumed bytes from src.
+func Decompress(src []byte) (bufpool.Buffer, int, error) {
+	return DecompressDict(src, nil)
+}
+
+// DecompressDict inflates the provided DEFLATE stream using dict as the preset
+// dictionary and returns the full output in a pooled bufpool.Buffer. The second
+// returned value reports how many bytes of src were consumed.
+func DecompressDict(src []byte, dict []byte) (bufpool.Buffer, int, error) {
+	d := bufferDecompressorPool.Get().(*bufferDecompressor)
+	defer bufferDecompressorPool.Put(d)
+
+	if err := d.inflater.reset(src, dict); err != nil {
+		return bufpool.Buffer{}, 0, err
+	}
+
+	out := bufpool.Borrow(bufpool.DefaultBufferCap)
+	out.Resize(0)
+
+	for {
+		if len(d.inflater.toRead) > 0 {
+			out.Append(d.inflater.toRead)
+			d.inflater.toRead = nil
+			continue
+		}
+		if d.inflater.err != nil {
+			if d.inflater.err == io.EOF {
+				return out, d.inflater.pos, nil
+			}
+			out.Release()
+			return bufpool.Buffer{}, 0, d.inflater.err
+		}
+		d.inflater.step(&d.inflater)
+		if d.inflater.err != nil && len(d.inflater.toRead) == 0 {
+			d.inflater.toRead = d.inflater.dict.readFlush()
+		}
+	}
+}