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US military drone losses in Iran war spur Pentagon call for cheap replacements.

A little robotic switch-flipper has become my sidekick in combating cockroaches. Before I got the SwitchBot Bot Rechargeable, I'd tiptoe through the dark every morning, hoping I wouldn't step on one of those terrible bugs scurrying around as I made my way to the light switch across the room. Now I'm ready for battle before […]

Waymo will ditch human supervisors in San Diego, Las Vegas, Tampa and Denver.

submitted by /u/DanielRosenwasser [link] [留言]

I wanted to understand how malloc actually works under the hood. Most explanations I found online described what an allocator does, but completely skipped over the "why" behind its design decisions. Rather than stopping at theory, I decided to build a cross-platform allocator in C that implements malloc , calloc , realloc , and free from scratch. This article documents the design of that allocator, the architectural tradeoffs I faced, and the core concepts I had to learn along the way. Table Of Contents Design Decisions Architecture Modern Allocator Strategies Core Concepts What's Next Project Overview A custom memory allocator does not create physical memory. Instead, it requests pages of raw virtual memory from the operating system and manages how that memory is partitioned, reused, resized, and released by the application. The goal of this educational project is to implement C's core memory management API using a modular, cross-platform architecture inspired by design principles found in modern allocators, rather than relying on legacy, single-platform tricks. Design Decisions #1: Why I am Skipping sbrk While many classic tutorials use sbrk for educational implementations, I deliberately chose a 100% mmap -based approach for two major reasons: sbrk is a fragile global bottleneck. It works by moving a single pointer (the program break) up and down. This means the allocator assumes it owns a contiguous line of memory. If a third-party library or another thread in the program secretly calls sbrk behind the scenes, the allocator's memory layout can break instantly. mmap , by contrast, provides isolated, independent chunks of memory. Cross-Platform Symmetry. Windows has absolutely no equivalent to sbrk , but it has a direct equivalent to mmap : VirtualAlloc . If we used sbrk , our architectural abstraction ( os_alloc ) would become awkward because Linux would deal with a moving pointer while Windows dealt with independent pages. Using mmap keeps the abstraction perfec

MarkDown - что это? [[Markdown]] — это язык разметки, с упрощенным до человекочитаемости синтаксисом. Markdown — создан Джоном Грубером ( John Gruber ) в 2004 году. Markdown — это фактически "микро" язык для трансляции "текста markdown"в подмножество языка XHTML. Markdown - итоговая презентация текста всегда документ HTML , и только потом если нужно следующим шагом PDF, др. стандарты документации. Markdown принципиально не может задействовать весь потенциал XHTML, результатом его работы всегда является ограниченный набор элементов. Markdown — это транслятор который при анализе интегрированного в "текст" markdown HTML/XHTML кода обязан по стандарту просто его транслировать в итоговый образ документа. Markdown — это, если цитировать автора > «Markdown — это инструмент преобразования текста в HTML для веб-писателей. Markdown позволяет писать в легко читаемом и удобном для написания текстовом формате, а затем преобразовывать его в структурно корректный HTML. ║ John Gruber » Примечание Термин транслятор , не обходимо понимать как сущность алгоритм Я не нашел программу реализующая концепт MarkDown по принципам John Gruber. Ни одна программа не умеет делать из Markdown валидный по John Gruber HTML. Все проверенные мною программы Obsidian, MarkText, Typora, на выходе из 10 строк генерируют портянку HTML в несколько тысяч строк!!! Причина Obsidian, Typora и MarkText используют Markdown не для веб-писателей и блогеров, а как формат хранения баз знаний (Knowledge Management)**. John Gruber - Wikipedia

The crust expands at mid-ocean rifts. But how?

We’re excited to announce our first ever Summer Bug Smash! Every app has its share of rockstar bugs....

It’s not a great time to shop for a gaming laptop. The unprecedented rise in cost for RAM (and storage to a slightly lesser extent) has made laptops with low-to-midrange specs cost much more than they should. Recent deals on gaming laptops worth your attention have been uninspiring, but one recently caught my eye: MSI’s […]

submitted by /u/mitousa [link] [留言]