imported brians code

[nestedvm.git] / src / org / xwt / mips / util / SeekableInputStream.java

diff --git a/src/org/xwt/mips/util/SeekableInputStream.java b/src/org/xwt/mips/util/SeekableInputStream.java
new file mode 100644 (file)
index 0000000..1dc0b0d
--- /dev/null
+++ b/src/org/xwt/mips/util/SeekableInputStream.java
@@ -0,0 +1,48 @@
+package org.xwt.mips.util;
+
+import java.io.*;
+
+public class SeekableInputStream implements SeekableData {
+    private byte[] buffer = new byte[4096];
+    private int bytesRead = 0;
+    private boolean eof = false;
+    private int pos;
+    private InputStream is;
+    
+    public SeekableInputStream(InputStream is) { this.is = is; }
+    
+    public int read(byte[] outbuf, int off, int len) throws IOException {
+        if(pos >= bytesRead && !eof) readTo(pos + 1);
+        len = Math.min(len,bytesRead-pos);
+        if(len <= 0) return -1;
+        System.arraycopy(buffer,pos,outbuf,off,len);
+        pos += len;
+        return len;
+    }
+    
+    private void readTo(int target) throws IOException {
+        if(target >= buffer.length) {
+            byte[] buf2 = new byte[Math.max(buffer.length+Math.min(buffer.length,65536),target)];
+            System.arraycopy(buffer,0,buf2,0,bytesRead);
+            buffer = buf2;
+        }
+        while(bytesRead < target) {
+            int n = is.read(buffer,bytesRead,buffer.length-bytesRead);
+            if(n == -1) {
+                eof = true;
+                break;
+            }
+            bytesRead += n;
+        }
+    }
+    
+    public int length() throws IOException {
+        while(!eof) readTo(bytesRead+4096);
+        return bytesRead;
+    }
+        
+    public int write(byte[] buf, int off, int len) throws IOException { throw new IOException("read-only"); }
+    public void seek(int pos) { this.pos = pos; }
+    public int pos() { return pos; }
+    public void close() throws IOException { is.close(); }
+}