[Courgette] Initial Implementation of LabelManager.

courgette/image_utils.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COURGETTE_IMAGE_UTILS_H_
 #define COURGETTE_IMAGE_UTILS_H_
 
 #include "base/basictypes.h"
 
 // COURGETTE_HISTOGRAM_TARGETS prints out a histogram of how frequently
 // different target addresses are referenced. Purely for debugging.
 #define COURGETTE_HISTOGRAM_TARGETS 0
 
 namespace courgette {
 
 typedef uint32 RVA;
 
+// A Label is a symbolic reference to an address.  Unlike a conventional
+// assembly language, we always know the address.  The address will later be
+// stored in a table and the Label will be replaced with the index into the
+// table.
+//
+// TODO(sra): Make fields private and add setters and getters.
+class Label {
+ public:
+  static const int kNoIndex = -1;

[grt (UTC plus 2), 2015/12/02 19:03:40]

nit:
  enum : int { kNoIndex = -1 };
as per
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/hDqJ4KBVqog/aaAfR...

[huangs, 2015/12/02 20:51:02]

Done.

+  Label() : rva_(0), index_(kNoIndex), count_(0) {}
+  explicit Label(RVA rva) : rva_(rva), index_(kNoIndex), count_(0) {}
+
+  bool operator==(const Label& other) const {
+    return rva_ == other.rva_ && index_ == other.index_ &&
+        count_ == other.count_;
+  }
+
+  RVA rva_;    // Address referred to by the label.

[grt (UTC plus 2), 2015/12/02 19:03:40]

use non-static member initializers here; e.g.:
  RVA rva_ = 0;
  int index_ = kNoIndex;
  int count_ = 0;
then remove the no-arg ctor altogether and only initialize rva_ in the other
ctor

[huangs, 2015/12/02 20:51:02]

Done.

+  int index_;  // Index of address in address table, kNoIndex until assigned.
+  int count_;
+};
+
 // These helper functions avoid the need for casts in the main code.
 inline uint16 ReadU16(const uint8* address, size_t offset) {
   return *reinterpret_cast<const uint16*>(address + offset);
 }
 
 inline uint32 ReadU32(const uint8* address, size_t offset) {
   return *reinterpret_cast<const uint32*>(address + offset);
 }
 
 inline uint64 ReadU64(const uint8* address, size_t offset) {
   return *reinterpret_cast<const uint64*>(address + offset);
 }
 
 inline uint16 Read16LittleEndian(const void* address) {
   return *reinterpret_cast<const uint16*>(address);
 }
 
 inline uint32 Read32LittleEndian(const void* address) {
   return *reinterpret_cast<const uint32*>(address);
 }
 
 inline uint64 Read64LittleEndian(const void* address) {
   return *reinterpret_cast<const uint64*>(address);
 }
 
 }  // namespace courgette
 
 #endif  // COURGETTE_IMAGE_UTILS_H_