CMSC 216程序写作、写作Programming程序

” CMSC 216程序写作、写作Programming程序CMSC 216 Project #5 Summer 2020Assembly Language Programming Due: Tue, Jul 21, 11:30 PM / Thu, Jul 23, 2019, 11:30 PM1 OverviewIn this project you will write AVR assembly code that corresponds to C code provided. There are two deadlinesassociated with this project: Tue, Jul 21, 11:30 PM – Your code must pass the first two public tests (PUBLIC 1, PUBLIC 2) in the submitserver. That is the only requirement for this deadline. Unlike previous projects, this first deadline isworth 1.5% of your course grade (NOT .5%). Notice you can still submit late for this part. Thu, Jul 23, 11:30 PM – Final deadline for the project. Notice you can still submit late (as usual).2 The MakefileIn the code distribution youll see two .c files for each function you need write; youll fill in the third (a .S file). x_reference.c – A reference C implementation of what you should write. x_driver.c – A main() that invokes your code (or the reference, depending on the Makefile) with variousinputs to print the output. x.S – Here is where you will define the function that in AVR assembly mimics the reference code.The Makefile has several rules. For example, for palindrome.S:make palindrome_s /* builds executable */make palindrome_s.run /* runs the program using simulator */make Palindrome_s.gdb /* runs the debugger */Although the base name of the assembly file is palindrome, we use palindrom s. You can also see the expectedoutput for a test based on the reference code (C code). For example, for palindrome.S:make palindrome_r.run /* runs the reference code (C code) */Notice the use of r. By the way, the driver code contains the public tests.3 SpecificationsFor each C routine, create an assembly program that produces the same output, given identical input. Yourprimary goal should be to produce a working version of each program. Your secondary goal is to make it nomore complicated than it needs to be.The input is provided by main(); you will not be expected to read integers or halt (cli/sleep) at the end of yourfunctions. You need only implement the routine, and the _driver.c will invoke the routine as needed.3.1 PalindromeAsk if it seems unclear. Palindromes are words or phrases that are the same forward as backwards, the C codeshows An example of how to do it.You may optimize the code, since array subscript operations are not straightforward. (You need to get to apointer to read from memory, the pointer is in X, Y, or Z, and although you can access at a constant offsetfrom a pointer (LDD Rd, Z+q) there is no single AVR instruction for array subscripting (variable pointer +variable offset).)CMSC 216作业写作、写作Programming作业3.2 FibonacciGiven n as a (uint16_t) parameter, it returns the nth Fibonacci number. This routine must be implemented ina recursive fashion otherwise you will lose most of the credit.3.3 Integer Square RootCompute the square root of an integer, using the bitwise algorithm at httpss://en.wikipedia.org/wiki/Integer_square_root.You will need the logical shift instructions. To shift left by one, lsl r24. To shift left by two, repeat theinstruction. Same for shifting right.3.4 Reverse Prefix SumTransform an array by adding the value at an index to the sum of the remainder of the array. Return thesum. The return value may be a 16-bit integer, but the array is of 8-bit integers. (Do not concern yourself withbehavior on overflow, just assume it will not happen.) The reverse prefix sum routine must be implementedin a recursive fashion otherwise you will lose most of the credit.3.5 Rules1. You may refer as much As you like to the output of avr-gcc -S. You may run make isqrt_reference.sfor example. We expect you to use this information only to help with individual fragments, for example,to learn how to add two words together, call shift instructions, find which instructions to execute, etc.We expect you to avoid Copying any code from the compiler output.2. (Restated…) You are expected to write the assembly code; this is preparation for exam questions. Youcan look at the compilers output if you need inspiration, but turning in something conspicuously similarto the compilers output will lose (at least) style points. The output of the compiler is inefficient,uncommented, and has an identifiable style that is more complicated than what humans would write.Notice that you dont need to look at the compilers output in order to implement the project.3. Dont change the C code.4. You dont have to worry about the maximum length of 80 for a line of code. (You might write longcomments.)5. Your comments should be descriptive of the intent, not of the action. A comment per line after a semicolondescriptive of what is happening is necessary. (I.e., stash n for later use is an ok comment. mover24 into r20 is not.) A description of the variable that each register represents is useful.6. Obey the callee-save And caller-save conventions; you must not clobber registers that the C driver doesnot expect you to clobber. If you have close control over only calling functions that you have personallywritten, you may be able to get away with skipping saving some caller-save registers; do not takeadvantage of this feature.7. Do not use rcall to call functions.4 Grading CriteriaYour project grade will be determined by the following:Results of public tests 50%Results of secret tests 38%Code style grading (verify by TA) 12%24.1 Style gradingFor this project, some style guidelines are obviously different, as you are writing in assembly language, not C.Please pay close attention to these guidelines:1. Reasonable and consistent indentation is still required. Your editor should help. Convention is to indentall instructions by one tab, to not indent labels, and to align per-line comments starting at the samecolumn. Our Examples are generally formatted this way.2. Your code must have a comment at the beginning with your name, university ID number, and UMDDirectory ID (i.e., your username on Grace).3. Your code must be thoroughly commented. Assembly language can easily become unreadable withoutproper documentation, so it is absolutely necessary that you comment your code.4. Use appropriate whitespace, especially between blocks of instructions that are performing differenttasks.5. There should be no need for global variables. Using global variables for format strings (e.g., .asciz %d)is fine.6. Obey the callee-save and caller-save conventions; you may not clobber registers that the C driver doesnot expect you to clobber.7. Your entire assembly code needs to be commented. You will lose significant points if more than 25% ofthe lines having instructions are uncommented.8. Make sure you leave at least one space between an instruction and the semicolon that starts a comment.You need comments next to the instructions (on the same line).9. You can use either the strlen (from the C string library) or your own (from the assembly exercise). Youdont need to include any files to use the C string library; you can call strlen as its linked using avr-gcc.10. Even if you are not planning to implement a function for a while, you need to provide an empty shell(i.e., name and ret instruction) that will allow the submit server to build your code.11. Commonly Seen Assembly mistakes can be found at: https://www.cs.umd.edu/~nelson/classes/resources/assembly_avr/#mistakes5 Other1. For your code to build in the submit server, you need to add to each .S file a shell of the function youneed to implement (similar to the provided fibonacci.S file).2. Feel free to use code examples provided in lecture.3. Submit often so you have a copy of your code in the submit server.4. Adding your own targets to the Makefile is fine, but do not modify the ones provided.6 SubmissionSubmit as usual.6.1 DeliverablesThe only files We will grade are your .S source files.37 Academic IntegrityPlease see the syllabus for project rules and academic integrity information. All programming assignments inthis course are to be written individually (unless explicitly indicated otherwise in a written project handout).Cooperation between students is a violation of the Code of Academic Integrity.4如有需要，请加QQ：99515681 或邮箱：99515681@qq.com

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