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
22 namespace open_vcdiff {
23
24 // VCDiffInstructionMap members and methods
25
26 VCDiffInstructionMap* VCDiffInstructionMap::default_instruction_map = NULL;
27
GetDefaultInstructionMap()28 VCDiffInstructionMap* 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
FindMaxSize(const unsigned char size_array[VCDiffCodeTableData::kCodeTableSize])37 static 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
ClearSizeOpcodeArray(int length,OpcodeOrNone * array)48 static void ClearSizeOpcodeArray(int length, OpcodeOrNone* array) {
49 for (int i = 0; i < length; ++i) {
50 array[i] = kNoOpcode;
51 }
52 }
53
NewSizeOpcodeArray(int length)54 static OpcodeOrNone* NewSizeOpcodeArray(int length) {
55 OpcodeOrNone* array = new OpcodeOrNone[length];
56 ClearSizeOpcodeArray(length, array);
57 return array;
58 }
59
FirstInstructionMap(int num_insts_and_modes,int max_size_1)60 VCDiffInstructionMap::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
~FirstInstructionMap()73 VCDiffInstructionMap::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
SecondInstructionMap(int num_insts_and_modes,int max_size_2)80 VCDiffInstructionMap::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
~SecondInstructionMap()89 VCDiffInstructionMap::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
Add(unsigned char first_opcode,unsigned char inst,unsigned char size,unsigned char mode,unsigned char second_opcode)103 void 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
Lookup(unsigned char first_opcode,unsigned char inst,unsigned char size,unsigned char mode) const127 OpcodeOrNone 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 //
VCDiffInstructionMap(const VCDiffCodeTableData & code_table_data,unsigned char max_mode)151 VCDiffInstructionMap::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