Converting mips instructions to machine code

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It only takes a minute to sign up. I am working on a problem that asks for the assembly language that would correspond to the following machine instruction in MIPS:.

Is this correct? I am going off an example but I am not entirely sure if its correct. Any help, advice would be appreciated.

Thank you. This is an andi instruction. I wrote some code and checked that an adi instruction has the above format in a disassembly listing. Looking up the MIPS registers for the rs and rt fields:. Sign up to join this community. The best answers are voted up and rise to the top.

Home Questions Tags Users Unanswered. Asked 4 years, 10 months ago. Active 4 years, 10 months ago. Viewed 1k times. Active Oldest Votes. You had the first two steps right: OXFF80 But not the rest. First separate out the opcode, starting from the left. All opcodes are 6 bits. So the opcode in binary, from the left, is: which is 0xC. Then you need to separate out the fields according to the MIPS I instruction format ; opcode rs rt immediate Opcode: 0xC rs: 0x03 rt: 0x02 Immediate: 0xFF80 I wrote some code and checked that an adi instruction has the above format in a disassembly listing.

I added that step.

MIPS Instruction Set Formats: R I J with Tables

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Help with converting machine language instruction into MIPS assembly instruction

Yet it parses R-format instructions add, sub, or, and, sltI-format beq, bne, lw, swbut not yet J-format. It's trivial to implement them.

Translating MIPS Assembly to Machine Code - Part 1

I haven't refreshed the README yet, but you can execute it with the -c option which transfers the parsed instruction as a comment after encoded line. Note that the registers are in reverse order, in contrast with the order that should be encoded in the binary representation:.

EDIT: There is also a work in progress a remake from me here. Darn it, I read the question backwards, and came up with a cool way to turn the binary into an opcode.

But it might point heh you in the right direction: using an array of pointers as an index to a bunch of strings. I'm going to describe the simpler binary-to-opcode concept first, then adapt the idea for opcode-to-binary. Firstthe question you didn't ask: binary into opcode. Consider using the bits of each section of the instruction word as a displacement pointer into an array that then points you to the appropriate string. At least, I think that's what I'd do.

Let's see how that would work for translating the last 6 bits of an R-type instruction using the Green Sheet. Here's the data segment, where I've defined strings not necessarily in order and a vector table which is in order. Now for the code. For the "funct", we want to mask out all but the 6 bits we're looking at, then shift left twice to make it a word pointer. For the others, you'd need to shift right.

Finallythe question you asked: how do you get started converting the text to the binary? Maybe you can use a similar array of strings and pointers to strings. Loop through the possible strings until you find a match or run out of strings to compare. You would need to set up a parallel array to indicate what sort of opcode it is, and what the associated bit pattern would be:. Get the pointer from opcodeXrefuse that to get the string from opcodeNamesand see if it's a match.

If not, go to the next word in opcodeXref. If it's a match, then use the same index you're at in opcodeXref to get the format from. Hope that's enough to get started.

Sounds like a pretty big project, especially with all that string manipulation not something Assembler is really intuitive for. Learn more. Mips Assembly code conversion to machine code Ask Question. Asked 6 years, 5 months ago. Active 4 years, 9 months ago. Viewed 13k times. Berjees Berjees 21 1 1 gold badge 1 1 silver badge 4 4 bronze badges. Do you understand how MIPS instructions encoded? If yes then you'll be able to convert any instructions to machine code.

If the answer is no then you should read a MIPS book then look at the instruction encoding and opcodes.Instruction encoding means the MIPS instruction are translated into binary numbers and then bring back to original format for human understanding decoding. Encoding should be done in a way that decoding is easy. MIPS instruction formats include:. Encoding format used for. Opcode stands for "operational code". It is the machine representation of instructions. It's is 6-bit long.

The first source register is rs. It's is 5-bit long. The destination register is rd. It stores the result of operations performed or rs and rt. I stands for "immediate value". An immediate is a bit value. It is operational code. J stands for "JUMP. J-type has a jump instruction and a target address.

General representation of J-Type is as follows:. In I-format opcode is a 6-bit jump instruction. It's similar to R-type instruction, the only difference is that it is reserved for floating point numbers.

converting mips instructions to machine code

It's similar to I-type instructionthe only difference is that it is reserved for floating point numbers. Comment to show me if it was helpful. Waiting for you! You may also like.R instructions are used when all the data values used by the instruction are located in registers. Where "OP" is the mnemonic for the particular instruction. As an example, the add mnemonic can be used as:.

In the main narrative of this book, the operands will be denoted by these names. Converting an R mnemonic into the equivalent binary machine code is performed in the following way:. Because several functions can have the same opcode, R-Type instructions need a function Func code to identify what exactly is being done - for example, 0x00 refers to an ALU operation and 0x20 refers to ADDing specifically. I instructions are used when the instruction must operate on an immediate value and a register value.

Immediate values may be a maximum of 16 bits long. Larger numbers may not be manipulated by immediate instructions. Where rt is the target register, rs is the source register, and IMM is the immediate value. The immediate value can be up to 16 bits long.

For instance, the addi instruction can be called as:. J instructions are used when a jump needs to be performed. The J instruction has the most space for an immediate value, because addresses are large numbers.

converting mips instructions to machine code

FR instructions are similar to the R instructions described above, except they are reserved for use with floating-point numbers:. FI instructions are similar to the I instructions described above, except they are reserved for use with floating-point numbers:.

The following table contains a listing of MIPS instructions and the corresponding opcodes. Opcode and funct numbers are all listed in hexadecimal. From Wikibooks, open books for an open world. MIPS Assembly. Namespaces Book Discussion. Views Read Edit View history. Policies and guidelines Contact us. In other languages Add links. This page was last edited on 13 Aprilat By using this site, you agree to the Terms of Use and Privacy Policy.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Software Engineering Stack Exchange is a question and answer site for professionals, academics, and students working within the systems development life cycle. It only takes a minute to sign up. For example if you open about a binary file in notepad you see a textually formatted representation of machine code. I assume that each byte symbol you see is the corresponding ascii character for it's binary value? Look at the instruction set documentation, and you will find entries like this one from a pic microcontroller for each instruction:.

The "encoding" line tells what that instruction looks like in binary. In this case, it always starts with 5 ones, then a don't care bit which can be either one or zerothen the "k"s stand for the literal you are adding. The first few bits are called an "opcode," are are unique for each instruction. The CPU basically looks at the opcode to see what instruction it is, then it knows to decode the "k"s as a number to be added.

It's tedious, but not that difficult to encode and decode. I had an undergrad class where we had to do it by hand in exams. To actually make a full executable file, you also have to do things like allocate memory, calculate branch offsets, and put it into a format like ELFdepending on your operating system.

Assembly opcodes have, for the most part, a one-to-one correspondence with the underlying machine instructions. So all you have to do is identify each opcode in the assembly language, map it to the corresponding machine instruction, and write the machine instruction out to a file, along with its corresponding parameters if any.

You then repeat the process for each additional opcode in the source file. Of course, it takes more than that to create an executable file that will properly load and run on an operating system, and most decent assemblers do have some additional capabilities beyond simple mapping of opcodes to machine instructions such as macros, for example. The first thing you need is something like this file.

converting mips instructions to machine code

This is the instruction database for x86 processors as used by the NASM assembler which I helped write, although not the parts that actually translate instructions. Lets pick an arbitrary line from the database:.Hot Threads.

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Help with converting machine language instruction into MIPS assembly instruction. Thread starter XodoX Start date Dec 2, I think it's easy, but I don't get it. Given the machine language instruction 0x What MIPS assembly instruction does it represent? I know the solution. I know I have to convert the numbers into binary first. So you have etc. Then you take the first 6 0's, and that's how you determine what type it is R-type? How do I do this? I know that there's a lsit where you can look it up, but you havewhich is 8 segments in total.

Dosen't make any sense.

MIPS Assembly/Instruction Formats

Mark44 Mentor. Insights Author. XodoX said:. Last edited: Dec 3, Ah, got it now! Thanks guys! However, I have been trying to to the reverse now. I suppose you first convert it to Hex 0x whatever number like above and then to the binary form.

How'd I do this? I thought the hex would be on the reference sheet, but I don't see anything. Once I have that, I just convert it to binary. No, you have it backwards.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up. I am doing some practice problems involving MIPS assembly instructions and machine code in hex. I am doing a problem but am uncertain if it is correct.

This is the problem, and what I did:. Thank you. This handy site agrees with you. Sign up to join this community. The best answers are voted up and rise to the top.

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