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x86-64 Register Set and Usage The x86-64 architecture includes 16 general-purpose registers that store 64-bit values. While these register are general-purpose, they follow conventional usage patterns. The registers r8 through r15 were added in the 80386 architecture extension. %rax: Return value register %rbx: Callee-saved register %rcx: 4th f ...

I/O Buffering Layers and Architecture Standard C I/O streams utilize user-space buffers (typically 8192 bytes) to batch read/write operations. POSIX functions like write() operate at a lower level, bypassing application buffers but still interacting with the kernel's page cache. Consequently, data sent via write() might temporarily reside in me ...

Linux provides two distinct approaches for file I/O operations: library functions (buffered/standard I/O) and system calls (unbuffered I/O). Understanding the differences between these approaches is essential for writing efficeint file handling code. Buffered I/O (Standard Library Functions) Buffered I/O functions are part of the C standard lib ...

Core Advantages of Memory Mapped I/O Higher performance than standard read/write operations by reducing redundant data copies between kernel space and user space Intuitive file access via regular memory pointer operations, eliminating the need for custom buffer management logic Native support for inter-process data sharing when multiple proces ...

Calculating Member Offsets To understand how structures are laid out in memory, it is useful to know the concept of an offset. The offset of a member is the distance in bytes from the start of the structure's base address. The first member always has an offset of 0. You can utilize the standard macro offsetof (defined in stddef.h) to inspect th ...