SDL_ALIGNED(3)

✨ SDL_ALIGNED ✨

okay bestie, this is a page from the SDL3 FUNCTIONS collection, and it's literally called SDL_ALIGNED(3). it's a tiny macro with big main character energy. let's get into it 💅

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🎀 NAME 🎀

SDL_ALIGNED — a macro that lets you specify data alignment. that's it, that's the whole job, and it does it flawlessly. periodt.

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🌸 SYNOPSIS 🌸

#include <SDL3/SDL_begin_code.h>

#define SDL_ALIGNED(x) __attribute__((aligned(x)))

like. look at her. one line of preprocessor and she's changing your memory layout. iconic.

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💖 DESCRIPTION 💖

so basically, this macro tells the compiler "hey. this datatype or this variable? it must be aligned to a specific byte count." no negotiating, no vibes-based alignment, we're being specific here.

for example:

// make sure this is struct is aligned to 16 bytes for SIMD access.
typedef struct {
   float x, y, z, w;
} SDL_ALIGNED(16) MySIMDAlignedData;

// make sure this one field in a struct is aligned to 16 bytes for SIMD access.
typedef struct {
   SomeStuff stuff;
   float SDL_ALIGNED(16) position[4];
   SomeOtherStuff other_stuff;
} MyStruct;

// make sure this variable is aligned to 32 bytes.
int SDL_ALIGNED(32) myval = 0;

see how it can go on the whole typedef, or just on one single field inside a struct, or on a plain old variable? versatile queen. 👑

🫶 real talk though: alignment is only guaranteed for things the compiler places — local variables on the stack, and global/static variables. that's the deal.

so if you wanna dynamically allocate something that respects this alignment, you gotta use SDL_aligned_alloc() or some other mechanism. don't just assume it'll work out, bestie, the compiler isn't gonna read your mind 😭

and here's the lowkey shady part: on compilers that don't support alignment, this macro is defined to an invalid symbol on purpose. not to be mean — it's so it becomes super obvious that your current compiler is likely to generate incorrect code when it sees this macro. it's giving "I'm telling you before you find out the hard way." 💀

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🌈 MACRO PARAMETERS 🌈

• x — the byte count to align to, so the data's address will be a multiple of this value. that's the one and only thing you hand her. ✨

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⭐ AVAILABILITY ⭐

this macro is available since SDL 3.4.0. so if you're on something older, sorry babe, no alignment for you 🙈

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and that's the whole page!! simple, clean, slays. this was brought to you by Simple Directmedia Layer, version SDL 3.4.18, dated in the SDL_ALIGNED(3) era — catch you in the next manpage, mwah 💜🦋🌸