Alright, I'm trying to write a vary basic modification to a program NOT written by me. I DO NOT have the source to it. I also do not care if this only works for a single version of the program, so hard coding offsets is feasible. Anyways, I've found the function and where it is called in the compiled program. .text:1901C88F loc_1901C88...
In x86 GNU Assembler there are different suffixes for memory related operations. E.g.: movb, movs, movw, movl, movq, movt(?) Now my question is the following: Does the suffix has ANY effect on how the processor is getting the data out of main memory or will always be one or more 32-bit (x86) chunks loaded into the cache ? What are t...
I want to know how objective C runtime handle arguments when I call a objective C method like [NSString stringWithFomat:@"%@, %@", @"Hello", @"World"] There are three arguments for this objective C call, how does it work compared to typical way on a ARM system. I have known register r0, r1, r2, r3 will hold first 4 arguments, how abou...
These are "Programmer Visible" x86-64 registers: What about the invisible registers? Just now I learned that MMU registers, Interrupt Descriptor Table (IDT) uses these invisible registers. I'm learning these things in the hard way. Is there any resource (book/documentation/etc) that gives me the complete picture at once? I am aware ...
When say 3 programs (executables) are loaded into memory the layout might look something like this: I've following questions: Is the concept of Virtual Memory limited to user processes? Because, I am wondering where does the Operating System Kernel, Drivers live? How is its memory layout? I want to know more about kernel side memory...
when compiling this in ml64.exe 64bit (masm64) the SSE command give me an error what do i need to do to include the SSE commands in 64 bit? .code foo PROC movlps [rdx], xmm7 ;;error A2070: invalid instruction operands movhlps xmm6, xmm7 movss [rdx+8], xmm6 ;;rror A2070: invalid instruction operands ret foo ENDP end i get t...
hi, i know this is kinda retarded but I just can't figure it out. I'm debugging this: xor eax,eax mov ah,[var1] mov al,[var2] call addition stop: jmp stop var1: db 5 var2: db 6 addition: add ah,al ret the numbers that I find on addresses var1 and var2 are 0x0E and 0x07. I know it's not segmented, but that ain't reason for it to d...
i want to find factorial a number which i take memory first.(intel 8085) edit: i'm beginner. i don't know how to write it's assembly codes. pseudo code: input n fact = 1 loop: ..multiply fact by n ..decrement n ..test n ..jump if not zero to loop output fact ...
I would like to dynamically allocate memory from an assembly program that does not link against the standard C library. Since brk(2) and sbrk(2) are unavailable on Mac OS X (10.6.2), what are the alternatives? (I'm guessing that it involves a Mach call, but there seems to be little documentation around that) ...
I'm studying JIT design with regard to dynamic languages VM implementation. I haven't done much Assembly since the 8086/8088 days, just a little here or there, so be nice if I'm out of sorts. As I understand it, the x86 (IA-32) architecture still has the same basic limited register set today that it always did, but the internal register...
Is it possible to allocate locally-scoped memory in assembly? For example, consider the following (completely contrived) situation: I have two macros, one of which is dependent on the other. The first is: minimum MACRO dest, num1, num2 ; Finds the minimum of two unsigned numbers, stores the result in dest And the second is: tripMin...
Recently I've started plaing with assembler under linux, there's good debuger, but comming from Ruby I'm missing simple REPL that would let me enter a line of assembler code and see the result on registers flags and stack. Can anyone point me in good direction? ...
Is there any code that I can look at to see how compression would be done in assembly? ...
So... I'm compiling into assembler, with gcc -S -O2 -m32: void h(int y){int x; x=y+1; f(y); f(2); } And it gives me the following: .file "sample.c" .text .p2align 4,,15 .globl h .type h, @function h: pushl %ebp movl %esp, %ebp subl $24, %esp movl 8(%ebp), %eax movl %eax, (%esp) call f movl $2, 8(%ebp) leave j...
When an assembly has an instruction like jmp f what happens to the stack and frame pointers? I mean - f is a label in memory right? How can we jump to different address in memory and not update our frame and stack pointers... EDIT: I am talking about Intel x86 assembly yes :) ...
So, I am kind of confused about drawing a stack frame for my assembly code. I have a feeling I started out wrong. Here is what I got so far, but as you can see I am confused at step 5, because I think my initial layout is wrong. Can you tell me where I went wrong? ...
I've written an assembler function to speed up a few things for image processing (images are created with CreateDIBSection). For Win32 the assembler code works without problems, but for Win64 I get a crash as soon as I try to access my array data. I put the relevant info in a struct and my assembler function gets a pointer to this stru...
I would like to learn the x86 Instruction Set Architecture. I don't meaning learning an assembly for x86. I want to understand the machine code baby. The reason is that I would like to write an assembler for x86. Then I want to write a compiler that compiles to that assembly. I know that there are the Intel manuals and AMD manuals that...
Is OSCompareAndSwap (Mac OS X) equivalent to CMPXCHG8B? ...
Is OSCompareAndSwap is immune to ABA problem like CMPXCHG8B? ...