Intial Thumb2 Sandbox (naclrev 6680)

src/trusted/validator_arm/address_set.h

 /*
  * Copyright 2009 The Native Client Authors.  All rights reserved.

[bsy, 2011/09/21 22:32:17]

11

  * Use of this source code is governed by a BSD-style license that can
  * be found in the LICENSE file.
  * Copyright 2009, Google Inc.
  */
 
 #ifndef NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_ARM_V2_ADDRESS_SET_H
 #define NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_ARM_V2_ADDRESS_SET_H
 
 #include <stdint.h>
 
 namespace nacl_arm_val {
 
 /*
  * A set of word addresses, implemented as a dense bitset.
  *
  * An AddressSet has a base address and a size, in bytes, of the space to
- * describe.  Describing N bytes costs N/32 bytes here, since we only record
- * word addresses (4-byte alignment) and pack 8 per byte.
+ * describe.  Describing N bytes costs N/16 bytes here, since we only record
+ * half-word addresses (2-byte alignment) and pack 8 per byte.
  *
- * Thus, an AddressSet covering the entire 256MB code region costs 8MB, plus
+ * Thus, an AddressSet covering the entire 256MB code region costs 16MB, plus
  * a small constant overhead (~16 bytes).
  */
 class AddressSet {
  public:
   /*
    * Creates an AddressSet describing 'size' bytes starting at 'base'.
    */
   AddressSet(uint32_t base, uint32_t size);
   ~AddressSet();
 
   /*
    * Adds an address to the set.
    * - If the address is already in the set, nothing changes.
    * - If the address is outside of this set's range (delimited by base and size
    *   provided at construction), nothing changes.
    * - If the address is not 4-byte aligned, the address of the 4-byte word

[Karl, 2011/09/19 19:56:05]

Doesn't this conflict with the 2-byte alignment comment on line 20?

    *   containing the address is added instead.
    */
   void add(uint32_t address);
 
   /*
    * Checks whether the AddressSet contains an address.  If the address is not
    * 4-byte aligned, the address of the 4-byte word containing the address is

[Karl, 2011/09/19 19:56:05]

Similar question here.

[jasonwkim, 2011/09/26 21:35:52]

both fixed

    * checked instead.
    */
   bool contains(uint32_t address) const;
 
   class Iterator {
    public:
     Iterator(const AddressSet &, uint32_t index, uint32_t shift);
     Iterator &operator++();
     bool operator!=(const Iterator &) const;
     uint32_t operator*() const;
@@ skipping 15 matching lines @@
   uint32_t * const bits_;
 
   // Disallow copies - we don't need them, and don't want to refcount bits_.
   AddressSet(const AddressSet &);
   AddressSet &operator=(const AddressSet &);
 };
 
 }  // namespace
 
 #endif  // NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_ARM_V2_ADDRESS_SET_H