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Questions tagged [low-level]

In terms of a computer system, low-level refers to the components that appears lower in the stack of system layers.

In terms of a computer system, low-level refers to the components that appears lower in the stack of system layers.

679 questions
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How does a compiler compile a compiler?

Coming from a high-level programming background, I am interested in learning about low-level programming. I want to know how a compiler is compiled? After looking at some articles in wiki, Numerical machine code is said to be lowest level language,…
wtsang02
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How does a computer draw the screen?

How does a computer draw anything to the screen at the lowest level (nothing about external libraries like X11)? Are there supposed to be assembly commands that do this? How exactly does the CPU control what appears on the screen?
Jonathan
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Real low level sound generation in C#?

Anyone knows of a sensible way to create an ARBITRARY sound wave in C# and play it back from the speakers? This issue has been coming back to every now and then for years, I always end up giving it up after a lot of failure without finding a…
jssyjrm
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iPhone iOS4 low-level camera control?

Is there a way to manually set low-level still-camera settings like shutter speed, aperture, or ISO in iOS4 on the iPhone 4? I don't think it exists in the official SDK but perhaps someone has found some private APIs to allow this? I find my iPhone…
Michael Liu
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What's inside the stack?

If I run a program, just like #include int main(int argc, char *argv[], char *env[]) { printf("My references are at %p, %p, %p\n", &argc, &argv, &env); } We can see that those regions are actually in the stack. But what else is there?…
ssice
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Is there an un-buffered I/O in Windows system?

I want to find low-level C/C++ APIs, equivalent with "write" in linux systems, that don't have a buffer. Is there one? The buffered I/O such as fread, fwrite are not what I wanted.
user53670
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How CPUs implement Instructions like MUL/MULT?

In different assembly languages MUL (x86)/MULT (mips) refer to multiplication. It is a black box for the programmer. I am interested in how actually a CPU accomplishes a multiplication regardless of the architecture. Lets say I have two 16-bit…
George
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Comparing Bitfields of Different Sizes

What happens if you use a bitwise operator (&, |, etc.) to compare two bitfields of different sizes? For example, comparing 0 1 1 0 with 0 0 1 0 0 0 0 1: 0 1 1 0 0 0 0 0 The smaller one is extended with zeros and pushed to the 0 0 1 0 0 0 0 1…
Maxpm
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Computing 8 horizontal sums of eight AVX single-precision floating-point vectors

I have 8 AVX vectors containing 8 floats each (64 floats in total) and I want to sum elements in each vector together (basically perform eight horizontal sums). For now, I'm using the following code: __m256 HorizontalSums(__m256 v0, __m256 v1,…
Witek902
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Bitwise subtraction in Python

This is a follow-up to my question yesterday: CMS kindly provided this example of using bitwise operators to add two numbers in C: #include int add(int x, int y) { int a, b; do { a = x & y; b = x ^ y; x = a…
user23126
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What Skill set should a low level programmer possess?

I am an embedded SW Engineer, with less than 3 yrs of experience. I aim to "sharpen the saw" continuously. I was wondering if there was anything specific to low level programming that C/C++ coders should be proficient with. What comes to my mind is…
embdeddCoder
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Real-Mode x86 ASM: How are the Basics Done?

I'm currently reading the boot.s file in the source for the first ever Linux kernel (assuming that 0.01 is indeed the first public release). I know C and ASM, the latter considerably less than the former. Even so, I seem to be able to understand and…
Louis
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Can I build an environment object from a memory address?

I found that we can build/reconstruct an external pointer from a memory address, see this example where I take a pointer from a data table object and rebuild it: # devtools::install_github("randy3k/xptr") iris_dt <-…
moodymudskipper
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Bluetooth protocol over wifi?

I'm looking to implement the Bluetooth protocol over a physical Wi-Fi based transport, if that makes sense. Basically my phone has Bluetooth, and my laptop has a Wi-Fi card (802.11a/b/g). I know that Wi-Fi operates over the range 2.412 GHz - 2.472…
martymcfly
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How to detect disassociation by AP reboot within station in PS mode

I'm writing a fairly low-level driver for a wireless card, and while most of the spec is fairly straightforward, I haven't wrapped my head around a single question yet: If my station is in power-save mode and its receiver is turned off for an…
Simon Richter
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