QB_ATOMIC_...GE_AND_ADD(3)

💖 NAME 💖

qb_atomic_int_exchange_and_add — the girlies call it atomic add-and-tell-you-what-it-was-before, and she is adding val to the integer that atomic points at, all atomically, no cap ✨

---

🌸 SYNOPSIS 🌸

okay so first you gotta bring her in:

#include <qb/qbatomic.h>

and then she looks like this, bestie:

int32_t qb_atomic_int_exchange_and_add(
    volatile int32_t QB_GNUC_MAY_ALIAS   *atomic,  /* a pointer to an integer */
    int32_t                               val      /* the value to add to *atomic */
);

like. the way she takes a volatile int32_t pointer with that QB_GNUC_MAY_ALIAS garnish and hands you back an int32_t?? iconic behavior honestly 💅

---

🎀 PARAMS 🎀

• atomic — a pointer to an integer 🫶 that's it, that's the whole vibe. she points at your int and she's ready.
• val — the value to add to *atomic ✨ this is the lil number getting poured into the pot.

---

🦋 DESCRIPTION 🦋

so here's the tea, bestie: she returns the value of *atomic just before the addition took place. not after. before. she's giving you the receipts of what it was, while quietly making it more. main character energy fr fr 👑

also?? she acts as a memory barrier. yes ma'am, ordering respected, no sneaky reordering happening on her watch. periodt 🌈

ngl if you're doing lock-free stuff and you need the old value and the increment in one indivisible lil moment, this is your girl. iykyk 💜

---

⭐ RETURN VALUE ⭐

the value of *atomic before the addition. that's the whole gift. the pre-add snapshot. the before pic 📸💖

---

🔥 SEE ALSO 🔥

• 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_pointer_compare_and_exchange(3)
• qb_atomic_pointer_set(3)

go read the whole friend group, they all slay in their own way 🧚✨

---

👑 COPYRIGHT 👑

Copyright (C) 2003 Sebastian Wilhelmi 💜

---

and that's the page, bestie!! from the libqb Programmer's Manual (that's the manual name, we folded it in up top like a lil bow 🎀), section 3, dated 2025-09-16, brought to you by LIBQB. mwah, go write something atomic, you ate 💅💖