QB_ATOMIC_...D_EXCHANGE(3)

💅 qb_atomic_pointer_compare_and_exchange — from the libqb Programmer's Manual ✨

okay bestie, sit down, hydrate, because we're talking about qb_atomic_pointer_compare_and_exchange, a function with a name so long it needs its own zip code 🫶. This one lives in the libqb manual (section 3, the library-calls girlies) and she is literally the compare-and-swap of the pointer world. iconic behaviour, no cap 💖

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🌸 NAME 🌸

qb_atomic_pointer_compare_and_exchange — she compares oldval with the pointer that atomic is pointing at, and if those two are equal, she atomically swaps *atomic with newval. that's it, that's the whole job, and she does it flawlessly 💅

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✨ SYNOPSIS ✨

#include <qb/qbatomic.h>

int32_t qb_atomic_pointer_compare_and_exchange(
    volatile void *QB_GNUC_MAY_ALIAS   *atomic,  /* a pointer to a void* */
    void                               *oldval,  /* the assumed old value of *atomic */
    void                               *newval   /* the new value of *atomic*/
);

like look at her. the return type is int32_t, the vibes are immaculate 🎀

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🦋 PARAMS 🦋

• atomic — a pointer to a void*. that's the lil spot she's gonna peek at and maybe swap out 👀
• oldval — the assumed old value of *atomic. your guess at what's currently chillin' in there, bestie 🤔
• newval — the new value of *atomic. what you want it to become if the guess was right ✨

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💜 DESCRIPTION 💜

she compares oldval against the pointer that atomic points to, and if they match? she swaps *atomic with newval atomically — all in one go, no interruptions, no half-finished nonsense, we do NOT do partial here 💅

Also acts as a memory barrier. yes ma'am. memory barrier. she's not just swapping, she's enforcing order in the universe. the way she does both at once… main character energy fr fr 🔥

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⭐ RETURN VALUE ⭐

• QB_TRUE if atomic was equal to oldval — you guessed right, she swapped, slay 🎉
• QB_FALSE otherwise — nope, the value wasn't what you thought, nothing happened, no harm done 🫠

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👑 SEE ALSO 👑

the whole friend group, they're all connected, iykyk:

• qb_atomic_int_set(3)
• qb_atomic_int_compare_and_exchange(3)
• qb_atomic_int_get(3)
• qb_atomic_int_add(3)
• qb_atomic_init(3)
• qb_atomic_pointer_get(3)
• qb_atomic_int_exchange_and_add(3)
• qb_atomic_pointer_set(3)

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🎀 COPYRIGHT 🎀

Copyright (C) 2003 Sebastian Wilhelmi

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that's the whole page bestie, go forth and atomically exchange responsibly 💖 this diva came to you from LIBQB, dated 2025-09-16, and yes she's still serving QB_ATOMIC_...D_EXCHANGE(3) energy in the year of our lord twenty twenty-five. periodt 🦋✨