♻️ refactor: split src into internal packages and cmd

internal/tsf/mmap_unix.go

@@ -0,0 +1,37 @@
+//go:build unix
+
+package tsf
+
+import (
+	"os"
+	"syscall"
+)
+
+func readFrameFile(filename string) (*frameFile, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = f.Close() }()
+
+	info, err := f.Stat()
+	if err != nil {
+		return nil, err
+	}
+	size := info.Size()
+	if size <= 0 || size != int64(int(size)) {
+		data, err := os.ReadFile(filename)
+		return &frameFile{data: data}, err
+	}
+	data, err := syscall.Mmap(int(f.Fd()), 0, int(size), syscall.PROT_READ, syscall.MAP_SHARED)
+	if err != nil {
+		data, err := os.ReadFile(filename)
+		return &frameFile{data: data}, err
+	}
+	return &frameFile{
+		data: data,
+		cleanup: func() error {
+			return syscall.Munmap(data)
+		},
+	}, nil
+}