1// Copyright 2008 Google Inc.
2// Author: Lincoln Smith
3//
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at
7//
8//      http://www.apache.org/licenses/LICENSE-2.0
9//
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15
16#include <config.h>
17#include "instruction_map.h"
18#include <string.h>  // memset
19#include "addrcache.h"
20#include "vcdiff_defs.h"
21
22namespace open_vcdiff {
23
24// VCDiffInstructionMap members and methods
25
26VCDiffInstructionMap* VCDiffInstructionMap::default_instruction_map = NULL;
27
28VCDiffInstructionMap* VCDiffInstructionMap::GetDefaultInstructionMap() {
29  if (!default_instruction_map) {
30    default_instruction_map = new VCDiffInstructionMap(
31        VCDiffCodeTableData::kDefaultCodeTableData,
32        VCDiffAddressCache::DefaultLastMode());
33  }
34  return default_instruction_map;
35}
36
37static unsigned char FindMaxSize(
38    const unsigned char size_array[VCDiffCodeTableData::kCodeTableSize]) {
39  unsigned char max_size = size_array[0];
40  for (int i = 1; i < VCDiffCodeTableData::kCodeTableSize; ++i) {
41    if (size_array[i] > max_size) {
42      max_size = size_array[i];
43    }
44  }
45  return max_size;
46}
47
48static void ClearSizeOpcodeArray(int length, OpcodeOrNone* array) {
49  for (int i = 0; i < length; ++i) {
50    array[i] = kNoOpcode;
51  }
52}
53
54static OpcodeOrNone* NewSizeOpcodeArray(int length) {
55  OpcodeOrNone* array = new OpcodeOrNone[length];
56  ClearSizeOpcodeArray(length, array);
57  return array;
58}
59
60VCDiffInstructionMap::FirstInstructionMap::FirstInstructionMap(
61    int num_insts_and_modes,
62    int max_size_1)
63    : num_instruction_type_modes_(num_insts_and_modes),
64      max_size_1_(max_size_1) {
65  first_opcodes_ = new OpcodeOrNone*[num_instruction_type_modes_];
66  for (int i = 0; i < num_instruction_type_modes_; ++i) {
67    // There must be at least (max_size_1_ + 1) elements in first_opcodes_
68    // because the element first_opcodes[max_size_1_] will be referenced.
69    first_opcodes_[i] = NewSizeOpcodeArray(max_size_1_ + 1);
70  }
71}
72
73VCDiffInstructionMap::FirstInstructionMap::~FirstInstructionMap() {
74  for (int i = 0; i < num_instruction_type_modes_; ++i) {
75    delete[] first_opcodes_[i];
76  }
77  delete[] first_opcodes_;
78}
79
80VCDiffInstructionMap::SecondInstructionMap::SecondInstructionMap(
81    int num_insts_and_modes,
82    int max_size_2)
83    : num_instruction_type_modes_(num_insts_and_modes),
84      max_size_2_(max_size_2) {
85  memset(second_opcodes_, 0, sizeof(second_opcodes_));
86}
87
88
89VCDiffInstructionMap::SecondInstructionMap::~SecondInstructionMap() {
90  for (int opcode = 0; opcode < VCDiffCodeTableData::kCodeTableSize; ++opcode) {
91    if (second_opcodes_[opcode] != NULL) {
92      for (int inst_mode = 0;
93           inst_mode < num_instruction_type_modes_;
94           ++inst_mode) {
95        // No need to check for NULL
96        delete[] second_opcodes_[opcode][inst_mode];
97      }
98      delete[] second_opcodes_[opcode];
99    }
100  }
101}
102
103void VCDiffInstructionMap::SecondInstructionMap::Add(
104    unsigned char first_opcode,
105    unsigned char inst,
106    unsigned char size,
107    unsigned char mode,
108    unsigned char second_opcode) {
109  OpcodeOrNone**& inst_mode_array = second_opcodes_[first_opcode];
110  if (!inst_mode_array) {
111    inst_mode_array = new OpcodeOrNone*[num_instruction_type_modes_];
112    memset(inst_mode_array,
113           0,
114           num_instruction_type_modes_ * sizeof(inst_mode_array[0]));
115  }
116  OpcodeOrNone*& size_array = inst_mode_array[inst + mode];
117  if (!size_array) {
118    // There must be at least (max_size_2_ + 1) elements in size_array
119    // because the element size_array[max_size_2_] will be referenced.
120    size_array = NewSizeOpcodeArray(max_size_2_ + 1);
121  }
122  if (size_array[size] == kNoOpcode) {
123    size_array[size] = second_opcode;
124  }
125}
126
127OpcodeOrNone VCDiffInstructionMap::SecondInstructionMap::Lookup(
128    unsigned char first_opcode,
129    unsigned char inst,
130    unsigned char size,
131    unsigned char mode) const {
132  if (size > max_size_2_) {
133    return kNoOpcode;
134  }
135  const OpcodeOrNone* const * const inst_mode_array =
136    second_opcodes_[first_opcode];
137  if (!inst_mode_array) {
138    return kNoOpcode;
139  }
140  int inst_mode = (inst == VCD_COPY) ? (inst + mode) : inst;
141  const OpcodeOrNone* const size_array = inst_mode_array[inst_mode];
142  if (!size_array) {
143    return kNoOpcode;
144  }
145  return size_array[size];
146}
147
148// Because a constructor should never fail, the caller must already
149// have run ValidateCodeTable() against the code table data.
150//
151VCDiffInstructionMap::VCDiffInstructionMap(
152    const VCDiffCodeTableData& code_table_data,
153    unsigned char max_mode)
154    : first_instruction_map_(VCD_LAST_INSTRUCTION_TYPE + max_mode + 1,
155                             FindMaxSize(code_table_data.size1)),
156      second_instruction_map_(VCD_LAST_INSTRUCTION_TYPE + max_mode + 1,
157                              FindMaxSize(code_table_data.size2)) {
158  // First pass to fill up first_instruction_map_
159  for (int opcode = 0; opcode < VCDiffCodeTableData::kCodeTableSize; ++opcode) {
160    if (code_table_data.inst2[opcode] == VCD_NOOP) {
161      // Single instruction.  If there is more than one opcode for the same
162      // inst, mode, and size, then the lowest-numbered opcode will always
163      // be used by the encoder, because of the descending loop.
164      first_instruction_map_.Add(code_table_data.inst1[opcode],
165                                 code_table_data.size1[opcode],
166                                 code_table_data.mode1[opcode],
167                                 opcode);
168    } else if (code_table_data.inst1[opcode] == VCD_NOOP) {
169      // An unusual case where inst1 == NOOP and inst2 == ADD, RUN, or COPY.
170      // This is valid under the standard, but unlikely to be used.
171      // Add it to the first instruction map as if inst1 and inst2 were swapped.
172      first_instruction_map_.Add(code_table_data.inst2[opcode],
173                                 code_table_data.size2[opcode],
174                                 code_table_data.mode2[opcode],
175                                 opcode);
176    }
177  }
178  // Second pass to fill up second_instruction_map_ (depends on first pass)
179  for (int opcode = 0; opcode < VCDiffCodeTableData::kCodeTableSize; ++opcode) {
180    if ((code_table_data.inst1[opcode] != VCD_NOOP) &&
181        (code_table_data.inst2[opcode] != VCD_NOOP)) {
182      // Double instruction.  Find the corresponding single instruction opcode
183      const OpcodeOrNone single_opcode =
184          LookupFirstOpcode(code_table_data.inst1[opcode],
185                            code_table_data.size1[opcode],
186                            code_table_data.mode1[opcode]);
187      if (single_opcode == kNoOpcode) continue;  // No single opcode found
188      second_instruction_map_.Add(static_cast<unsigned char>(single_opcode),
189                                  code_table_data.inst2[opcode],
190                                  code_table_data.size2[opcode],
191                                  code_table_data.mode2[opcode],
192                                  opcode);
193    }
194  }
195}
196
197};  // namespace open_vcdiff
198