diff --git a/se/sics/mspsim/chip/CC2520SPI.java b/se/sics/mspsim/chip/CC2520SPI.java
index f8a33ee..fff57f0 100644
--- a/se/sics/mspsim/chip/CC2520SPI.java
+++ b/se/sics/mspsim/chip/CC2520SPI.java
@@ -54,7 +54,7 @@ public class CC2520SPI {
     SPICommand[] commands = new SPICommand[256];
     
     CC2520SPI() {
-
+        /* set up the commands */
         for (int i = 0; i < spiCommands.length; i++) {
             SPICommand c = spiCommands[i];
             int maxv = 1 << (8 - c.bitCount);
@@ -70,8 +70,18 @@ public class CC2520SPI {
         }    
     }
     
+    SPICommand getCommand(int cmd) {
+        if (cmd < 256 && commands[cmd] != null)
+            return commands[cmd];
+        return null;
+    }
+    
+    
     public static void main(String[] args) {
-        new CC2520SPI();
+        CC2520SPI spi = new CC2520SPI();
+        SPICommand cmd = spi.getCommand(0xff);
+        /* commands that take infinite number of bytes have the bitfield ... */
+        System.out.println("Has ... => " + cmd.getBitField("..."));
     }
     
 }
diff --git a/se/sics/mspsim/chip/SPICommand.java b/se/sics/mspsim/chip/SPICommand.java
index d0b5640..55ebfe0 100644
--- a/se/sics/mspsim/chip/SPICommand.java
+++ b/se/sics/mspsim/chip/SPICommand.java
@@ -1,6 +1,7 @@
 package se.sics.mspsim.chip;
 
 import java.util.ArrayList;
+import java.util.Iterator;
 
 public class SPICommand {
 /*    
@@ -93,6 +94,9 @@ public class SPICommand {
         if (start != 0) {
             System.out.println("Bitfield: " + currentName + ": [" +
                     start + " - " + (c - 1) + "]");
+            if (bitFields == null)
+                bitFields = new ArrayList<SPICommand.BitField>();
+            bitFields.add(new BitField(currentName, start, c - 1));
         }
 
         System.out.printf("Value %x\n", value);
@@ -113,11 +117,20 @@ public class SPICommand {
         return true;
     }
     
+    /* for any command that is executable (finite commands) */
     public boolean executeSPICommand(int[] spiData) {
         System.out.println("Command " + name + " not implemented...");
         return true;
     }
     
+    public BitField getBitField(String arg) {
+        for (BitField b : bitFields) {
+            if (b.name.equals(arg)) return b;
+        }
+        /* not existing ... */
+        return null;
+    }
+    
     public static void main(String[] args) {
         SPICommand c = new SPICommand("MEMXCP 0 1 0 1 0 1 0 p c c c c c c c c a a a a e e e e a a a a a a a a e e e e e e e e") {
             public boolean executeSPICommand(int[] spiData) {