1 | // Copyright (c) 2015-2020 The Khronos Group Inc. |
2 | // Modifications Copyright (C) 2020 Advanced Micro Devices, Inc. All rights |
3 | // reserved. |
4 | // |
5 | // Licensed under the Apache License, Version 2.0 (the "License"); |
6 | // you may not use this file except in compliance with the License. |
7 | // You may obtain a copy of the License at |
8 | // |
9 | // http://www.apache.org/licenses/LICENSE-2.0 |
10 | // |
11 | // Unless required by applicable law or agreed to in writing, software |
12 | // distributed under the License is distributed on an "AS IS" BASIS, |
13 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
14 | // See the License for the specific language governing permissions and |
15 | // limitations under the License. |
16 | |
17 | // This file contains a disassembler: It converts a SPIR-V binary |
18 | // to text. |
19 | |
20 | #include <algorithm> |
21 | #include <cassert> |
22 | #include <cstring> |
23 | #include <iomanip> |
24 | #include <memory> |
25 | #include <unordered_map> |
26 | #include <utility> |
27 | |
28 | #include "source/assembly_grammar.h" |
29 | #include "source/binary.h" |
30 | #include "source/diagnostic.h" |
31 | #include "source/disassemble.h" |
32 | #include "source/ext_inst.h" |
33 | #include "source/name_mapper.h" |
34 | #include "source/opcode.h" |
35 | #include "source/parsed_operand.h" |
36 | #include "source/print.h" |
37 | #include "source/spirv_constant.h" |
38 | #include "source/spirv_endian.h" |
39 | #include "source/util/hex_float.h" |
40 | #include "source/util/make_unique.h" |
41 | #include "spirv-tools/libspirv.h" |
42 | |
43 | namespace { |
44 | |
45 | // A Disassembler instance converts a SPIR-V binary to its assembly |
46 | // representation. |
47 | class Disassembler { |
48 | public: |
49 | Disassembler(const spvtools::AssemblyGrammar& grammar, uint32_t options, |
50 | spvtools::NameMapper name_mapper) |
51 | : grammar_(grammar), |
52 | print_(spvIsInBitfield(SPV_BINARY_TO_TEXT_OPTION_PRINT, options)), |
53 | color_(spvIsInBitfield(SPV_BINARY_TO_TEXT_OPTION_COLOR, options)), |
54 | indent_(spvIsInBitfield(SPV_BINARY_TO_TEXT_OPTION_INDENT, options) |
55 | ? kStandardIndent |
56 | : 0), |
57 | text_(), |
58 | out_(print_ ? out_stream() : out_stream(text_)), |
59 | stream_(out_.get()), |
60 | header_(!spvIsInBitfield(SPV_BINARY_TO_TEXT_OPTION_NO_HEADER, options)), |
61 | show_byte_offset_(spvIsInBitfield( |
62 | SPV_BINARY_TO_TEXT_OPTION_SHOW_BYTE_OFFSET, options)), |
63 | byte_offset_(0), |
64 | name_mapper_(std::move(name_mapper)) {} |
65 | |
66 | // Emits the assembly header for the module, and sets up internal state |
67 | // so subsequent callbacks can handle the cases where the entire module |
68 | // is either big-endian or little-endian. |
69 | spv_result_t HandleHeader(spv_endianness_t endian, uint32_t version, |
70 | uint32_t generator, uint32_t id_bound, |
71 | uint32_t schema); |
72 | // Emits the assembly text for the given instruction. |
73 | spv_result_t HandleInstruction(const spv_parsed_instruction_t& inst); |
74 | |
75 | // If not printing, populates text_result with the accumulated text. |
76 | // Returns SPV_SUCCESS on success. |
77 | spv_result_t SaveTextResult(spv_text* text_result) const; |
78 | |
79 | private: |
80 | enum { kStandardIndent = 15 }; |
81 | |
82 | using out_stream = spvtools::out_stream; |
83 | |
84 | // Emits an operand for the given instruction, where the instruction |
85 | // is at offset words from the start of the binary. |
86 | void EmitOperand(const spv_parsed_instruction_t& inst, |
87 | const uint16_t operand_index); |
88 | |
89 | // Emits a mask expression for the given mask word of the specified type. |
90 | void EmitMaskOperand(const spv_operand_type_t type, const uint32_t word); |
91 | |
92 | // Resets the output color, if color is turned on. |
93 | void ResetColor() { |
94 | if (color_) out_.get() << spvtools::clr::reset{print_}; |
95 | } |
96 | // Sets the output to grey, if color is turned on. |
97 | void SetGrey() { |
98 | if (color_) out_.get() << spvtools::clr::grey{print_}; |
99 | } |
100 | // Sets the output to blue, if color is turned on. |
101 | void SetBlue() { |
102 | if (color_) out_.get() << spvtools::clr::blue{print_}; |
103 | } |
104 | // Sets the output to yellow, if color is turned on. |
105 | void SetYellow() { |
106 | if (color_) out_.get() << spvtools::clr::yellow{print_}; |
107 | } |
108 | // Sets the output to red, if color is turned on. |
109 | void SetRed() { |
110 | if (color_) out_.get() << spvtools::clr::red{print_}; |
111 | } |
112 | // Sets the output to green, if color is turned on. |
113 | void SetGreen() { |
114 | if (color_) out_.get() << spvtools::clr::green{print_}; |
115 | } |
116 | |
117 | const spvtools::AssemblyGrammar& grammar_; |
118 | const bool print_; // Should we also print to the standard output stream? |
119 | const bool color_; // Should we print in colour? |
120 | const int indent_; // How much to indent. 0 means don't indent |
121 | spv_endianness_t endian_; // The detected endianness of the binary. |
122 | std::stringstream text_; // Captures the text, if not printing. |
123 | out_stream out_; // The Output stream. Either to text_ or standard output. |
124 | std::ostream& stream_; // The output std::stream. |
125 | const bool ; // Should we output header as the leading comment? |
126 | const bool show_byte_offset_; // Should we print byte offset, in hex? |
127 | size_t byte_offset_; // The number of bytes processed so far. |
128 | spvtools::NameMapper name_mapper_; |
129 | }; |
130 | |
131 | spv_result_t Disassembler::HandleHeader(spv_endianness_t endian, |
132 | uint32_t version, uint32_t generator, |
133 | uint32_t id_bound, uint32_t schema) { |
134 | endian_ = endian; |
135 | |
136 | if (header_) { |
137 | SetGrey(); |
138 | const char* generator_tool = |
139 | spvGeneratorStr(SPV_GENERATOR_TOOL_PART(generator)); |
140 | stream_ << "; SPIR-V\n" |
141 | << "; Version: " << SPV_SPIRV_VERSION_MAJOR_PART(version) << "." |
142 | << SPV_SPIRV_VERSION_MINOR_PART(version) << "\n" |
143 | << "; Generator: " << generator_tool; |
144 | // For unknown tools, print the numeric tool value. |
145 | if (0 == strcmp("Unknown" , generator_tool)) { |
146 | stream_ << "(" << SPV_GENERATOR_TOOL_PART(generator) << ")" ; |
147 | } |
148 | // Print the miscellaneous part of the generator word on the same |
149 | // line as the tool name. |
150 | stream_ << "; " << SPV_GENERATOR_MISC_PART(generator) << "\n" |
151 | << "; Bound: " << id_bound << "\n" |
152 | << "; Schema: " << schema << "\n" ; |
153 | ResetColor(); |
154 | } |
155 | |
156 | byte_offset_ = SPV_INDEX_INSTRUCTION * sizeof(uint32_t); |
157 | |
158 | return SPV_SUCCESS; |
159 | } |
160 | |
161 | spv_result_t Disassembler::HandleInstruction( |
162 | const spv_parsed_instruction_t& inst) { |
163 | if (inst.result_id) { |
164 | SetBlue(); |
165 | const std::string id_name = name_mapper_(inst.result_id); |
166 | if (indent_) |
167 | stream_ << std::setw(std::max(0, indent_ - 3 - int(id_name.size()))); |
168 | stream_ << "%" << id_name; |
169 | ResetColor(); |
170 | stream_ << " = " ; |
171 | } else { |
172 | stream_ << std::string(indent_, ' '); |
173 | } |
174 | |
175 | stream_ << "Op" << spvOpcodeString(static_cast<SpvOp>(inst.opcode)); |
176 | |
177 | for (uint16_t i = 0; i < inst.num_operands; i++) { |
178 | const spv_operand_type_t type = inst.operands[i].type; |
179 | assert(type != SPV_OPERAND_TYPE_NONE); |
180 | if (type == SPV_OPERAND_TYPE_RESULT_ID) continue; |
181 | stream_ << " " ; |
182 | EmitOperand(inst, i); |
183 | } |
184 | |
185 | if (show_byte_offset_) { |
186 | SetGrey(); |
187 | auto saved_flags = stream_.flags(); |
188 | auto saved_fill = stream_.fill(); |
189 | stream_ << " ; 0x" << std::setw(8) << std::hex << std::setfill('0') |
190 | << byte_offset_; |
191 | stream_.flags(saved_flags); |
192 | stream_.fill(saved_fill); |
193 | ResetColor(); |
194 | } |
195 | |
196 | byte_offset_ += inst.num_words * sizeof(uint32_t); |
197 | |
198 | stream_ << "\n" ; |
199 | return SPV_SUCCESS; |
200 | } |
201 | |
202 | void Disassembler::EmitOperand(const spv_parsed_instruction_t& inst, |
203 | const uint16_t operand_index) { |
204 | assert(operand_index < inst.num_operands); |
205 | const spv_parsed_operand_t& operand = inst.operands[operand_index]; |
206 | const uint32_t word = inst.words[operand.offset]; |
207 | switch (operand.type) { |
208 | case SPV_OPERAND_TYPE_RESULT_ID: |
209 | assert(false && "<result-id> is not supposed to be handled here" ); |
210 | SetBlue(); |
211 | stream_ << "%" << name_mapper_(word); |
212 | break; |
213 | case SPV_OPERAND_TYPE_ID: |
214 | case SPV_OPERAND_TYPE_TYPE_ID: |
215 | case SPV_OPERAND_TYPE_SCOPE_ID: |
216 | case SPV_OPERAND_TYPE_MEMORY_SEMANTICS_ID: |
217 | SetYellow(); |
218 | stream_ << "%" << name_mapper_(word); |
219 | break; |
220 | case SPV_OPERAND_TYPE_EXTENSION_INSTRUCTION_NUMBER: { |
221 | spv_ext_inst_desc ext_inst; |
222 | SetRed(); |
223 | if (grammar_.lookupExtInst(inst.ext_inst_type, word, &ext_inst) == |
224 | SPV_SUCCESS) { |
225 | stream_ << ext_inst->name; |
226 | } else { |
227 | if (!spvExtInstIsNonSemantic(inst.ext_inst_type)) { |
228 | assert(false && "should have caught this earlier" ); |
229 | } else { |
230 | // for non-semantic instruction sets we can just print the number |
231 | stream_ << word; |
232 | } |
233 | } |
234 | } break; |
235 | case SPV_OPERAND_TYPE_SPEC_CONSTANT_OP_NUMBER: { |
236 | spv_opcode_desc opcode_desc; |
237 | if (grammar_.lookupOpcode(SpvOp(word), &opcode_desc)) |
238 | assert(false && "should have caught this earlier" ); |
239 | SetRed(); |
240 | stream_ << opcode_desc->name; |
241 | } break; |
242 | case SPV_OPERAND_TYPE_LITERAL_INTEGER: |
243 | case SPV_OPERAND_TYPE_TYPED_LITERAL_NUMBER: { |
244 | SetRed(); |
245 | spvtools::EmitNumericLiteral(&stream_, inst, operand); |
246 | ResetColor(); |
247 | } break; |
248 | case SPV_OPERAND_TYPE_LITERAL_STRING: { |
249 | stream_ << "\"" ; |
250 | SetGreen(); |
251 | // Strings are always little-endian, and null-terminated. |
252 | // Write out the characters, escaping as needed, and without copying |
253 | // the entire string. |
254 | auto c_str = reinterpret_cast<const char*>(inst.words + operand.offset); |
255 | for (auto p = c_str; *p; ++p) { |
256 | if (*p == '"' || *p == '\\') stream_ << '\\'; |
257 | stream_ << *p; |
258 | } |
259 | ResetColor(); |
260 | stream_ << '"'; |
261 | } break; |
262 | case SPV_OPERAND_TYPE_CAPABILITY: |
263 | case SPV_OPERAND_TYPE_SOURCE_LANGUAGE: |
264 | case SPV_OPERAND_TYPE_EXECUTION_MODEL: |
265 | case SPV_OPERAND_TYPE_ADDRESSING_MODEL: |
266 | case SPV_OPERAND_TYPE_MEMORY_MODEL: |
267 | case SPV_OPERAND_TYPE_EXECUTION_MODE: |
268 | case SPV_OPERAND_TYPE_STORAGE_CLASS: |
269 | case SPV_OPERAND_TYPE_DIMENSIONALITY: |
270 | case SPV_OPERAND_TYPE_SAMPLER_ADDRESSING_MODE: |
271 | case SPV_OPERAND_TYPE_SAMPLER_FILTER_MODE: |
272 | case SPV_OPERAND_TYPE_SAMPLER_IMAGE_FORMAT: |
273 | case SPV_OPERAND_TYPE_FP_ROUNDING_MODE: |
274 | case SPV_OPERAND_TYPE_LINKAGE_TYPE: |
275 | case SPV_OPERAND_TYPE_ACCESS_QUALIFIER: |
276 | case SPV_OPERAND_TYPE_FUNCTION_PARAMETER_ATTRIBUTE: |
277 | case SPV_OPERAND_TYPE_DECORATION: |
278 | case SPV_OPERAND_TYPE_BUILT_IN: |
279 | case SPV_OPERAND_TYPE_GROUP_OPERATION: |
280 | case SPV_OPERAND_TYPE_KERNEL_ENQ_FLAGS: |
281 | case SPV_OPERAND_TYPE_KERNEL_PROFILING_INFO: |
282 | case SPV_OPERAND_TYPE_RAY_FLAGS: |
283 | case SPV_OPERAND_TYPE_RAY_QUERY_INTERSECTION: |
284 | case SPV_OPERAND_TYPE_RAY_QUERY_COMMITTED_INTERSECTION_TYPE: |
285 | case SPV_OPERAND_TYPE_RAY_QUERY_CANDIDATE_INTERSECTION_TYPE: |
286 | case SPV_OPERAND_TYPE_DEBUG_BASE_TYPE_ATTRIBUTE_ENCODING: |
287 | case SPV_OPERAND_TYPE_DEBUG_COMPOSITE_TYPE: |
288 | case SPV_OPERAND_TYPE_DEBUG_TYPE_QUALIFIER: |
289 | case SPV_OPERAND_TYPE_DEBUG_OPERATION: |
290 | case SPV_OPERAND_TYPE_CLDEBUG100_DEBUG_BASE_TYPE_ATTRIBUTE_ENCODING: |
291 | case SPV_OPERAND_TYPE_CLDEBUG100_DEBUG_COMPOSITE_TYPE: |
292 | case SPV_OPERAND_TYPE_CLDEBUG100_DEBUG_TYPE_QUALIFIER: |
293 | case SPV_OPERAND_TYPE_CLDEBUG100_DEBUG_OPERATION: |
294 | case SPV_OPERAND_TYPE_CLDEBUG100_DEBUG_IMPORTED_ENTITY: { |
295 | spv_operand_desc entry; |
296 | if (grammar_.lookupOperand(operand.type, word, &entry)) |
297 | assert(false && "should have caught this earlier" ); |
298 | stream_ << entry->name; |
299 | } break; |
300 | case SPV_OPERAND_TYPE_FP_FAST_MATH_MODE: |
301 | case SPV_OPERAND_TYPE_FUNCTION_CONTROL: |
302 | case SPV_OPERAND_TYPE_LOOP_CONTROL: |
303 | case SPV_OPERAND_TYPE_IMAGE: |
304 | case SPV_OPERAND_TYPE_MEMORY_ACCESS: |
305 | case SPV_OPERAND_TYPE_SELECTION_CONTROL: |
306 | case SPV_OPERAND_TYPE_DEBUG_INFO_FLAGS: |
307 | case SPV_OPERAND_TYPE_CLDEBUG100_DEBUG_INFO_FLAGS: |
308 | EmitMaskOperand(operand.type, word); |
309 | break; |
310 | default: |
311 | assert(false && "unhandled or invalid case" ); |
312 | } |
313 | ResetColor(); |
314 | } |
315 | |
316 | void Disassembler::EmitMaskOperand(const spv_operand_type_t type, |
317 | const uint32_t word) { |
318 | // Scan the mask from least significant bit to most significant bit. For each |
319 | // set bit, emit the name of that bit. Separate multiple names with '|'. |
320 | uint32_t remaining_word = word; |
321 | uint32_t mask; |
322 | int num_emitted = 0; |
323 | for (mask = 1; remaining_word; mask <<= 1) { |
324 | if (remaining_word & mask) { |
325 | remaining_word ^= mask; |
326 | spv_operand_desc entry; |
327 | if (grammar_.lookupOperand(type, mask, &entry)) |
328 | assert(false && "should have caught this earlier" ); |
329 | if (num_emitted) stream_ << "|" ; |
330 | stream_ << entry->name; |
331 | num_emitted++; |
332 | } |
333 | } |
334 | if (!num_emitted) { |
335 | // An operand value of 0 was provided, so represent it by the name |
336 | // of the 0 value. In many cases, that's "None". |
337 | spv_operand_desc entry; |
338 | if (SPV_SUCCESS == grammar_.lookupOperand(type, 0, &entry)) |
339 | stream_ << entry->name; |
340 | } |
341 | } |
342 | |
343 | spv_result_t Disassembler::SaveTextResult(spv_text* text_result) const { |
344 | if (!print_) { |
345 | size_t length = text_.str().size(); |
346 | char* str = new char[length + 1]; |
347 | if (!str) return SPV_ERROR_OUT_OF_MEMORY; |
348 | strncpy(str, text_.str().c_str(), length + 1); |
349 | spv_text text = new spv_text_t(); |
350 | if (!text) { |
351 | delete[] str; |
352 | return SPV_ERROR_OUT_OF_MEMORY; |
353 | } |
354 | text->str = str; |
355 | text->length = length; |
356 | *text_result = text; |
357 | } |
358 | return SPV_SUCCESS; |
359 | } |
360 | |
361 | spv_result_t (void* user_data, spv_endianness_t endian, |
362 | uint32_t /* magic */, uint32_t version, |
363 | uint32_t generator, uint32_t id_bound, |
364 | uint32_t schema) { |
365 | assert(user_data); |
366 | auto disassembler = static_cast<Disassembler*>(user_data); |
367 | return disassembler->HandleHeader(endian, version, generator, id_bound, |
368 | schema); |
369 | } |
370 | |
371 | spv_result_t DisassembleInstruction( |
372 | void* user_data, const spv_parsed_instruction_t* parsed_instruction) { |
373 | assert(user_data); |
374 | auto disassembler = static_cast<Disassembler*>(user_data); |
375 | return disassembler->HandleInstruction(*parsed_instruction); |
376 | } |
377 | |
378 | // Simple wrapper class to provide extra data necessary for targeted |
379 | // instruction disassembly. |
380 | class WrappedDisassembler { |
381 | public: |
382 | WrappedDisassembler(Disassembler* dis, const uint32_t* binary, size_t wc) |
383 | : disassembler_(dis), inst_binary_(binary), word_count_(wc) {} |
384 | |
385 | Disassembler* disassembler() { return disassembler_; } |
386 | const uint32_t* inst_binary() const { return inst_binary_; } |
387 | size_t word_count() const { return word_count_; } |
388 | |
389 | private: |
390 | Disassembler* disassembler_; |
391 | const uint32_t* inst_binary_; |
392 | const size_t word_count_; |
393 | }; |
394 | |
395 | spv_result_t (void* user_data, spv_endianness_t endian, |
396 | uint32_t /* magic */, uint32_t version, |
397 | uint32_t generator, uint32_t id_bound, |
398 | uint32_t schema) { |
399 | assert(user_data); |
400 | auto wrapped = static_cast<WrappedDisassembler*>(user_data); |
401 | return wrapped->disassembler()->HandleHeader(endian, version, generator, |
402 | id_bound, schema); |
403 | } |
404 | |
405 | spv_result_t DisassembleTargetInstruction( |
406 | void* user_data, const spv_parsed_instruction_t* parsed_instruction) { |
407 | assert(user_data); |
408 | auto wrapped = static_cast<WrappedDisassembler*>(user_data); |
409 | // Check if this is the instruction we want to disassemble. |
410 | if (wrapped->word_count() == parsed_instruction->num_words && |
411 | std::equal(wrapped->inst_binary(), |
412 | wrapped->inst_binary() + wrapped->word_count(), |
413 | parsed_instruction->words)) { |
414 | // Found the target instruction. Disassemble it and signal that we should |
415 | // stop searching so we don't output the same instruction again. |
416 | if (auto error = |
417 | wrapped->disassembler()->HandleInstruction(*parsed_instruction)) |
418 | return error; |
419 | return SPV_REQUESTED_TERMINATION; |
420 | } |
421 | return SPV_SUCCESS; |
422 | } |
423 | |
424 | } // namespace |
425 | |
426 | spv_result_t spvBinaryToText(const spv_const_context context, |
427 | const uint32_t* code, const size_t wordCount, |
428 | const uint32_t options, spv_text* pText, |
429 | spv_diagnostic* pDiagnostic) { |
430 | spv_context_t hijack_context = *context; |
431 | if (pDiagnostic) { |
432 | *pDiagnostic = nullptr; |
433 | spvtools::UseDiagnosticAsMessageConsumer(&hijack_context, pDiagnostic); |
434 | } |
435 | |
436 | const spvtools::AssemblyGrammar grammar(&hijack_context); |
437 | if (!grammar.isValid()) return SPV_ERROR_INVALID_TABLE; |
438 | |
439 | // Generate friendly names for Ids if requested. |
440 | std::unique_ptr<spvtools::FriendlyNameMapper> friendly_mapper; |
441 | spvtools::NameMapper name_mapper = spvtools::GetTrivialNameMapper(); |
442 | if (options & SPV_BINARY_TO_TEXT_OPTION_FRIENDLY_NAMES) { |
443 | friendly_mapper = spvtools::MakeUnique<spvtools::FriendlyNameMapper>( |
444 | &hijack_context, code, wordCount); |
445 | name_mapper = friendly_mapper->GetNameMapper(); |
446 | } |
447 | |
448 | // Now disassemble! |
449 | Disassembler disassembler(grammar, options, name_mapper); |
450 | if (auto error = spvBinaryParse(&hijack_context, &disassembler, code, |
451 | wordCount, DisassembleHeader, |
452 | DisassembleInstruction, pDiagnostic)) { |
453 | return error; |
454 | } |
455 | |
456 | return disassembler.SaveTextResult(pText); |
457 | } |
458 | |
459 | std::string spvtools::spvInstructionBinaryToText(const spv_target_env env, |
460 | const uint32_t* instCode, |
461 | const size_t instWordCount, |
462 | const uint32_t* code, |
463 | const size_t wordCount, |
464 | const uint32_t options) { |
465 | spv_context context = spvContextCreate(env); |
466 | const spvtools::AssemblyGrammar grammar(context); |
467 | if (!grammar.isValid()) { |
468 | spvContextDestroy(context); |
469 | return "" ; |
470 | } |
471 | |
472 | // Generate friendly names for Ids if requested. |
473 | std::unique_ptr<spvtools::FriendlyNameMapper> friendly_mapper; |
474 | spvtools::NameMapper name_mapper = spvtools::GetTrivialNameMapper(); |
475 | if (options & SPV_BINARY_TO_TEXT_OPTION_FRIENDLY_NAMES) { |
476 | friendly_mapper = spvtools::MakeUnique<spvtools::FriendlyNameMapper>( |
477 | context, code, wordCount); |
478 | name_mapper = friendly_mapper->GetNameMapper(); |
479 | } |
480 | |
481 | // Now disassemble! |
482 | Disassembler disassembler(grammar, options, name_mapper); |
483 | WrappedDisassembler wrapped(&disassembler, instCode, instWordCount); |
484 | spvBinaryParse(context, &wrapped, code, wordCount, DisassembleTargetHeader, |
485 | DisassembleTargetInstruction, nullptr); |
486 | |
487 | spv_text text = nullptr; |
488 | std::string output; |
489 | if (disassembler.SaveTextResult(&text) == SPV_SUCCESS) { |
490 | output.assign(text->str, text->str + text->length); |
491 | // Drop trailing newline characters. |
492 | while (!output.empty() && output.back() == '\n') output.pop_back(); |
493 | } |
494 | spvTextDestroy(text); |
495 | spvContextDestroy(context); |
496 | |
497 | return output; |
498 | } |
499 | |