” COMP9017编程 写作、Java，PythonCOMP2017 / COMP9017 Assignment 2Due: 11:59PM Sunday 11 April 2021 local Sydney timeThis assignment is worth 15% of your final assessmentTask DescriptionIn this assignment you will be implementing and performing operations on a simple virtual machine.You will need to emulate this virtual machine to store and reference variables and stack frame contextsbefore reading a set of pseudo assembly instructions that dictate the operations that should beperformed on the stack. Your program will take a single command line argument being the path tothe file containing your x2017 assembly code.Before attempting this assignment it would be a good idea to familiarise yourself with the stack,registers, stack frames, stack pointers, program counters, assembly and machine code. A strongunderstanding of these concepts is Essential to completing this assignment. Section 3.6 and 3.7 ofthe course textbook provide specific detail to x86_64 architecture, however you can review these as areference.In order to complete this assignment at a technical level you should revise your understanding ofbitwise operations, file IO, pointers and arrays.Some implementation details are purposefully left ambiguous; you have the freedom to decide on thespecifics yourself. Additionally this description does not define all possible behaviour that can beexhibited by the system; some error cases are not documented. You are expected to gracefully reportand handle these errors yourself.The ArchitectureIn this assignment you will be emulating an 8 bit architecture. The memory model of this architectureconsists of: RAM – Contains 28addresses of 1 byte each Register Bank – 8 registers of 1 byte each Program Code – Memory required to store the program to be executed.For full marks the total size on disk of your programs binary should not exceed 10kb.1COMP2017 / COMP9017During execution you should not store any information about the state of the machine outside of theRAM and the register bank.Note: A register stores a single Value using a fixed bit width. It the size of a register corresponding tothe processor word size, in this case 8 bits. Think of them as a primitive variable. Physical processorhardware is constrained, and the number of registers is always fixed. There are registers which servespecific purposes, and those which are general. Please identify these in the description and considerthem for your solution. You need not consider special purpose registers, such as floating point, in thisassignment.Program Code: x2017Our virtual machine will be operating on a home brewed x2017 assembly language. You will beprovided with binaries in this language to run on your virtual machine. Each operation within x2017contains an operation specifier code (op code) and takes zero, one or two arguments. Argumentsare expressed as one of four different types, while operation codes are selected from a table. Thearguments of each function precede the opcode and are expressed as follows:([Second Value][Second Type])([First Value][First Type])[Operation Code]A collection of these operations will form a function.The type is a two bit field and specifies the type of the preceding value.00 – value: 1 byte long. The value in the preceding 8 bits should be interpreted as a single bytevalue.01 – register address: 3 bits long. This address refers to one of the eight fixed registers10 – stack symbol: 5 bits long. This refers to a particular symbol within the current stack frame.11 – pointer valued: 5 bits long. This treats the contents of the address referred to by a particularsymbol within the current stack frame as a variable. Pointers may reference variables ondifferent stack frames.The second address and Address type field is optional and will not be required for unary operations.The address type specifies whether it is a stack address, a value, a register address or a pointer toanother stack address. Stack addresses are 7 bits long, register addresses are 3 bits long and valuesare 8 bits long and pointer addresses are also 7 bits long.A stack symbol is a value that is associated with an address on the stack; it is up to you to finda cogent method of allocating stack space to symbols. Symbols only exist within the scope of thecurrent function; should two functions use the same symbol then they are not referencing the sameregion of memory.While the exact memory layout within the stack frame is open to interpretation, four registers arereserved for special values. 0x07 Stores the program counter.Page 2 of 8COMP2017 / COMP9017 0x06 Will not be referenced by the program; this register exists for your personal use. 0x05 Will not be referenced by the program; this register exists for your personal use. 0x04 Will not be referenced by the program; this register exists for your personal use.Registers in the range 0x00-0x03 are general purpose registers and may be explicitly referenced by aprogram.The opcodes associated with x2017 instructions are detailed below. You will need to read each ofthe op-codes and implement the operation on the memory specified.Opcodes:000 – [MOV A B] – Copies the value at some point B in memory to another point A in memory(register or stack). The destination may not be value typed.001 – [CAL A] – Calls another function the first argument is a single byte (using the VALUE type)containing the label of the calling function.010 – [RET] – Terminates the current function, this is guaranteed to always exist at the end of eachfunction. There may be more Than one RET in a function. If this function is the entry-point,then the program terminates.011 – [REF A B] – Takes a stack symbol B and stores its corresponding stack address in A.100 – [ADD A B] – Takes two register addresses and ADDs their values, storing the result in the firstlisted register.101 – [PRINT A] – Takes any address type and prints the contents to a new line of standard outputas an unsigned integer.110 – [NOT A] – Takes a register address and performs a bitwise not operation on the value at thataddress. The result is stored in the same register111 – [EQU A] – Takes a register address and tests if it equals zero. The value in the register will beset to 1 if it is 0, or 0 if it is not. The result is stored in the same register.The state of the registers is preserved between CAL and RET operations.In the event that the execution of this program enters an undefined state; for example if the amountof stack memory required to execute the program exceeds the RAM buffer, then you should print anappropriate error to standard error and return 1 on exiting main.The value of the program counter register should reference the current opcode. Your program shouldincrement the program counter before executing the associated instruction. You may wish to considerwhat may happen when the program counter is modified during the execution of an instruction.Binary File Format:The first few bits of the file are padding bits to ensure that the total number of bits in the file accumulatesto a whole number of bytes. The number of padding bits will always be strictly less than onebyte.Page 3 of 8COMP2017 / COMP9017The file is broken up into a Number of functions. Each function is defined with a three bit headerdictating the label of the function and the number of arguments, and a five bit tail specifying thenumber of instructions in the function. The function with the label 0 is the entry point and should beexecuted first.[Padding bits][function label (3 bits)][OPCODE][OPCODE]…[RET][Number of instructions (5 bits)][function label (3 bits)][OPCODE][OPCODE]…[RET][Number of instructions (5 bits)]ExampleThe following assembly function moves the values 3 and 5 to separate registers before adding them,moving the value to the stack and returning.Some equivalent C code might look like this:#define BYTE unsigned char // Because all values are 1 bytevoid main(){register BYTE reg_0 = 3; // Storing the value 3 at register 1register BYTE reg_1 = 5; // Storing the value 5 at register 2reg_0 += reg_1; // ADD The two registers, save the value at r1BYTE A = reg_0; // Store the value from register 1 at stack symbol Areturn; // Return}We can Consider some equivalent x2017 assembly:FUNC LABEL 0MOV REG 0 VAL 3MOV REG 1 VAL 5ADD REG 0 REG 1MOV STK A REG 0RETPage 4 of 8COMP2017 / COMP9017And this assembly can be compiled down to binary:00000 # Padding for the file000 # Function labeled 000000011|00|000|01|000 # MOV REG 0 VAL 300000101|00|001|01|000 # MOV REG 1 VAL 5001|01|000|01|100 # ADD REG 0 REG 1000|01|00000|10|000 # MOV STK A REG 0010 # RETOr without the comments:00000000000000110000001000000001010000101000001010000110000001000001000001000101And finally; hex formatted:\x00\x03\x02\x01B\x82\x86\x04\x10EYour program will take the path to one of these binary files as a command line argument and executethe instructions within.MilestoneAs part of this assignment, you are expected to submit a milestone prior to your final submission. Themilestone task will be to create a disassembler for x2017 binaries. That is; your program will take anx2017 binary and print its contents in a human readable form. Given a path to a file containing:\x00\x03\x02\x01\x42\x82\x86\x04\x10\x45You would be expected to print:FUNC LABEL 0MOV REG 0 VAL 3MOV REG 1 VAL 5ADD REG 0 REG 1MOV STK A REG 0RETYou may notice that the symbol information is stripped in the binary; that is that the value A neverappears. You should print each unique symbol within each stack frame as a single capital letter inorder of appearance starting with A. As there are 25 possible symbols and only 26 letters of thealphabet symbols after Z should instead be displayed as lower case letters starting at a.Indentation in the output of this program should be performed using four spaces.Page 5 of 8COMP2017 / COMP9017Compilation and ExecutionYour program will be compiled by running the default rule of a make file. Upon compiling yourprogram should produce a single vm_x2017 binary. Your binary should accept a single argument inthe form of the path to a x2017 binary file to execute.make./vm_x2017 x2017_binaryYour milestone disassembler will be compiled and run using the make rule make objdump_x2017make objdump_x2017./objdump_x2017 x2017_binaryTests will be compiled and run using two make rules; make tests and make run_tests.make testsmake run_testsThese rules should Build any tests you need, then execute each test and report back on your correctness.Failing to adhere to these conventions will prevent your markers from running your code and tests. Inthis circumstance you will be awarded a mark of 0 for this assignment.Marking CriteriaThe following is the marking breakdown, each point contributes a portion to the total 15% of theassignment. You will receive a result of zero if your program fails to compile.Marks are allocated on the basis of: Milestone Correctness – 3 – Passing automatic test cases, a number of tests will not be releasedor run until after your final submission. Final Correctness – 3 – Passing automatic test cases, a number of tests will not be released orrun until after your final submission. Binary size – 2 – If all test cases are passed, then an additional 2 marks are awarded if the binarydoes not exceed 10kB. If the test cases are not passed, then these marks are not awarded. Solution Discussion – 7 – You will need to answer questions from a COMP2017 teaching staffmember regarding your implementation. You will be required to attend a zoom session withCOMP2017 teaching staff member after the code submission deadline. A reasonable attemptwill need to be made, otherwise you will receive zero for the assessment.In this session, you will be asked to explain:Page 6 of 8COMP2017 / COMP9017 How your program counter is affected by the opcodes executed. How your code organises and manages the stack memory for function calls. What are the edge cases you considered for when your program returns 1. Answer further questions. Your code will also be assessed on C coding style conventions (see Ed resources). Cleancode will attract the best grade.Correctness is based on: vm_x2017 – return value of the program vm_x2017 – printed standard output of the x2017 binary program execution (all PRINT ops) objdump_x2017 – printed standard output of the disassemblerAdditionally marks will be deducted on the basis of: Compilation – If your Submission does not compile you will receive an automatic mark of zerofor this assessment. Style – 2 – Poor code readability will result in the deduction of up to 2 marks. Your code andtest cases should be neatly divided between header and source files in appropriate directories,should be commented, contain meaningful variable names, useful indentation, white space andfunctions should be used appropriately. Please refer to this courses style guide for more details. Tests – 2 – A lack of tests, or a lack of thorough testing will result in the deduction of up to 2marks. Please provide your test cases along with appropriate scripts to build, run and report theresults of your tests. As a number of tests will not be released until after your final submissionyou are strongly encouraged to test all aspects of your program. Graceful Error Handling – 1 – The description above contains a number of undefined behaviours.Your program should gracefully catch each of these error, report, and exit. Should your programcrash marks will be deducted. Your error messages should be meaningful but you will not beprovided with a standard format. Memory Leaks – Code that leaks memory will receive a mark of 0. Savvy readers may note thatthis task does not necessarily require dynamically allocated memory.Warning: Any attempts to deceive or disrupt the marking system will result in an immediate zero forthe entire assignment. Negative marks can be assigned if you do not follow the assignment descriptionor if your code is unnecessarily or deliberately obfuscated.Helpful Hints / Where to Start Start by reading in the operation code from the above example, you will need to use bitwiseoperations here and should refer to the relevant lectures and tutorial sheets.Page 7 of 8COMP2017 / COMP9017 You do not know the number of padding bits at the start of the file in advance! Consider howyou might calculate this. Start with the milestone; you cant execute the program until you have parsed it; and parsingthe program is a requirement for completing the milestone. Spend some time working out how the CAL and RET operations work before you start writingyour implementation. You will not be tested on the internal state of your stack and as a result you have a degree offlexibility in your implementation. You will need to decide how to manage memory on yourstack yourself. Invalid inputs may be provided; when you detect such a case you should return 1 and exit withan appropriate error message. When writing test cases you may find it useful to write your own ascii to x2017 compiler andbundle it with your test builder. You have three registers and an arbitrary amount of stack space set aside for your own use; thesuccess of your approach will depend on how you utilise this memory.Academic declarationBy submitting this assignment you declare the following:I declare that I have read and understood the University of Sydney Student Plagiarism: Coursework Policy and Procedure, and except where specificallyacknowledged, the work contained in this assignment/project is my own work, and has not been copied from other sources or been previously submittedfor award or assessment.I understand that failure to comply with the Student Plagiarism: Coursework Policy and Procedure can lead to severe penalties as outlined underChapter 8 of the University of Sydney By-Law 1999 (as amended). These penalties may be imposed in cases where any significant portion of mysubmitted work has been copied without proper acknowledgment from other sources, including published works, the Internet, existing programs, thework of other students, or work previously submitted for other awards or assessments.I realise that I may be asked to identify those portions of the work contributed by me and required to demonstrate my knowledge of the relevant materialby answering oral questions or by Undertaking supplementary work, either written or in the laboratory, in order to arrive at the final assessment mark.I acknowledge that the School of Computer Science, in assessing this assignment, may reproduce it entirely, may provide a copy to another member offaculty, and/or communicate a copy of this assignment to a plagiarism checking service or in-house computer program, and that a copy of the assignmentmay be maintained by the service or the School of Computer Science for the purpose of future plagiarism checking.请加QQ：99515681 或邮箱：99515681@qq.com WX：codehelp
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