Put the checksum of vector table into 0x1c

The checksum of the entries 0 to 6 should be calculated and put at address 0x1c.

lpc.c

@@ -147,10 +147,22 @@ void lpc_write(struct lpc_device *dev, const struct sprog_data *d) {
       chunk.data[i] = d->data[offset+i];
     
     for(i=data_size; i<chunk_size; i++)
-      chunk.data[i] = 0;
+      chunk.data[i] = 0xff;
     
     chunk.size = chunk_size;
     
+    if(offset==0) {
+    /* calculate the checksum and put it at 0x1c in the vector table */
+      j = 0;
+      for(i=0; i<0x1c; i+=4)
+	j += chunk.data[i] | chunk.data[i+1]<<8 | chunk.data[i+2]<<16 | chunk.data[i+3]<<24;
+      j = -j;
+      for(i=0; i<4; i++) {
+	chunk.data[0x1c+i] = j & 0xff;
+	j >>= 8;
+      }
+    }
+    
     lpc_write_ram(dev, &chunk, 0x10000400);
     
     sprog_info("Copying to Flash...\n");