I had an assignment and I almost completed. But I found it tough to write integer to a file in MIPS. Are there anyways to write Int to a file in MIPS?
Related
This MIPS simulator will read in a text file consisting of LC3100 machine code instructions (represented as decimal values), and execute the program, then display the values of register files and memory after each instruction is completed.
I do not understand how this can be done and simply need a format for what steps I need to take in order to create the simulator in MIPS. Do I write code in C++ or write the code in MIPS? How do I read files if it is in MIPS? Honestly, just confused.
I do not know where I need to start from. This is what I am asking to help figure out.
I'd imagine you'd want to create some global variables that represent your registers and memory:
int memory[0x80000000/4];
int reg_v0;
int reg_t0;
int* reg_pc;
// etc
And then define some functions that mimic the way MIPS behaves. You'll need to read up on how the CPU operates (which is why this example function may seem arbitrary but really it isn't.)
void MIPS_multu(int regA, int regB)
{
// void because we're writing to global variables.
uint64_t temp = regA * regB;
reg_hi = temp >> 32;
reg_lo = (temp & 0x00000000FFFFFFFF);
}
Finally, you'll need to understand how MIPS instructions are encoded and create a routine that can unpack them and select the correct function.
int memory[0x80000000/4];
int reg_v0;
int reg_t0;
int* reg_pc;
// etc
int main()
{
reg_pc = &memory[0];
while (reg_pc < &memory[0x80000000/4])
// chances are this is either invalid C or just bad practice,
// but I can't think of a better way to express the idea
{
int temp = *reg_pc;
// use bitwise operators etc to figure out what the instruction represents,
// and switch cases to pick the functions.
reg_pc++;
}
}
As anything with CUDA, the most basic things are sometimes the hardest...
So...I just want to copy a variable from the CPU to a GPU's constant variable, and I am having a hard time.
This is what i have:
__constant__ int contadorlinhasx_d;
int main(){
(...)
int contadorlinhasx=100;
status=cudaMemcpyToSymbol(contadorlinhasx_d,contadorlinhasx,1*sizeof(int),0,cudaMemcpyHostToDevice);
And i get this error
presortx.cu(222): error: no instance of overloaded function "cudaMemcpyToSymbol" matches the argument list
argument types are: (int, int, unsigned long, int, cudaMemcpyKind)
Could anyone help me? I know it is some stupid error, but I am tired of googling it, and I have spent almost 30 minutes just trying to copy a stupid variable :/
Thanks in advance
You need to do something like
cudaMemcpyToSymbol("contadorlinhasx_d",
&contadorlinhasx,
1*sizeof(int),
0,
cudaMemcpyHostToDevice);
[Note this is the old API call, now deprecated in CUDA 4.0 and newer]
or
cudaMemcpyToSymbol(contadorlinhasx_d,
&contadorlinhasx,
1*sizeof(int),
0,
cudaMemcpyHostToDevice);
If you look at the API documentation, the first two arguments are pointers. The first can either be a string, which will force a symbol lookup internally in the API (pre CUDA 4), or a device symbol address (CUDA 4 and later). The second argument is the address of the host source memory for the copy. The compiler error message is pretty explicit - you are passing the wrong types of argument and the compiler can't find an instance in the library which matches.
I am reading the CUDA 5.0 samples (AdvancedQuickSort) now. However, I cannot understand this sample totally due to following codes:
// Now compute my own personal offset within this. I need to know how many
// threads with a lane ID less than mine are going to write to the same buffer
// as me. We can use popc to implement a single-operation warp scan in this case.
unsigned lane_mask_lt;
asm( "mov.u32 %0, %%lanemask_lt;" : "=r"(lane_mask_lt) );
unsigned int my_mask = greater ? gt_mask : lt_mask;
unsigned int my_offset = __popc(my_mask & lane_mask_lt);
which is in the __global__ void qsort_warp function, especially for this assemble language in the codes. Can anyone help me to explain the meaning of this assemble language?
%lanemask_lt is a special, read-only register in PTX assembly which is initialized with a 32-bit mask with bits set in positions less than the thread’s lane number in the warp. The inline PTX you have posted is simply reading the value of that register and storing it in a variable where it can be used in the subsequent C++ code you posted.
Every version of the CUDA toolkit ships with a PTX assembly lanugage reference guide you can use to look up things like this.
I am looking at a very suspicious disassembled MIPS code of a C application
80019B90 jal loc_80032EB4
loc_80032EB4 is in the middle of another function's body, I've specially checked that no other code is loaded at this address in runtime and calling that function this way(passing some code in the beginning) can be useful. But how is it possible to do in C? It's not a goto as you can't goto to another function and normal function call will always "jal" to the beginning. Can this be some hand optinmimzation?
Update:
Simplified layout of both functions, callee:
sub_80032E88 (lz77_decode)
... save registers ...
80032E90 addiu $sp, -8
... allocate memory for decompressed data ...
80032EB0 move DECOMPRESSED_DATA_POINTER_A1, $v0
loc_80032EB4:
80032EB4 lw $t7, 0(PACKED_DATA_POINTER_A0)
... actual data decompression ...
80032F4C jr $ra
caller:
80019ACC addiu $sp, -0x30
... some not related code ...
80019B88 lw $a1, off_80018084 // A predefined buffer is used instead of allocating it for decompressed data
80019B90 jal loc_80032EB4
80019B94 move $a0, $s0
... some other code and function epilogue ...
Update 2:
I've checked if this can be a case of setjmp/longjmp usage, but in my tests I can always see calls to setjmp and longjmp functions in disassembled code, not a direct jump.
Update 3:
I've tried using GCC-specific ability to get label pointers and casted this pointer to function, result is close to what I want but disassembled code is still different as instead of using jal with exaxct address it calculating it runtime, maybe I am just unable to force compiler to see this value as constant, becouse of scope issues.
Since it is a data decompression function from a game system, it is very likely that this function is hand optimized assembly with multiple entry points. Multiple entry points aren't commonly used, so it is difficult to find a publicly available example, but here is an old thread from the gcc mailing list that suggests a possible use for this technique.
The gist is that if you have two functions where one function F1 has code that is a subset of the other function, F2's code, then the code for F2 can fall through into the code for F1. In your case, F2 allocates memory for the decompressed data, and F1 assumes that the memory allocation has already been done. I'm pretty sure that GCC 2.9x cannot generate code like this.
It is not possible to directly translate this construct from assembler into standard C, because you cannot goto another function in C, but this is perfectly legal in assembler code. The gcc mailing list thread suggests a couple of work-arounds to express the same idea in C.
If you look at the dis-assembled code for the decompression it will likely have a different style than compiler generated code. There may even be some use of opcodes, like find first set bit that the compiler cannot generate from C.
The title pretty much sums this up. I am writing a program in 32-bit MIPS Assembly Language (using the MARS emulator) for a school project and I'm having zero luck reading in int values > 2,147,483,647.
I spent a decent amount of time hunting around the internet and in my book to no avail. This is not central to the assignment (which, if you happen to know it is impossible, you probably already realized) but curiosity is killing this cat. Now that I've hit this brick wall, I must know for sure.
Notes:
I'm specifically looking for a way to grab an unsigned int as opposed to taking a float or a double.
The standard code for grabbing an int with syscall:
li $v0, 5
syscall
move $t0, $v0
The error that occurs when 2 500 000 000 is passed at prompt for integer:
Error in C:\DEV\....... line 57: Runtime exception at
0x004000034: invalid integer input (syscall 5)
Help me Obi-Wan, you're my only hope!
You'll need to use a different system call -- MARS is throwing the exception, not anything "inside" the MIPS CPU. Try, for instance, syscalls 8 or 12 (read string and read character). Note that, as a result, you'll have to implement a lot more of the parsing yourself to make these work.
Alternatively, you might try reading a double (syscall 7) and converting it to an integer...
There's a full list of MARS syscalls online at:
http://courses.missouristate.edu/KenVollmar/MARS/Help/SyscallHelp.html