cpu_capabilities(3)

💅 cpu_capabilities(3) — the Allegro manual, but make it cute ✨

okay bestie, sit down, we're talking about cpu_capabilities — a little global from the Allegro game programming library that tells you what your CPU can actually do. it's giving "tell me your red flags but it's processor instructions" 💖

🌸 SYNOPSIS 🌸

#include <allegro.h>

extern int cpu_capabilities;

like. that's it. one extern int. she's lowkey simple but highkey important 🎀

✨ DESCRIPTION ✨

so cpu_capabilities holds a bunch of CPU flags that say which features your current CPU has. and not just one — it can be any combination of these, all OR-ed together in one int. let's go through the whole roster, no skipping, periodt 👑

• CPU_ID — this one means the "cpuid" instruction is available. and bestie, this matters: if this flag is set, then all Allegro CPU variables are 100% reliable. if it's not set? there may be some mistakes 😭 so if you don't see CPU_ID, don't be out here trusting everything you read, okay?
• CPU_FPU — an FPU is available 💫 (floating point, she's here)
• CPU_IA64 — running on an Intel 64 bit CPU
• CPU_AMD64 — running on an AMD 64 bit CPU
• CPU_MMX — Intel MMX instruction set is available 🔥
• CPU_MMXPLUS — Intel MMX+ instruction set is available
• CPU_SSE — Intel SSE instruction set is available ✨
• CPU_SSE2 — Intel SSE2 instruction set is available ✨
• CPU_SSE3 — Intel SSE3 instruction set is available ✨
• CPU_3DNOW — AMD 3DNow! instruction set is available
• CPU_ENH3DNOW — AMD Enhanced 3DNow! instruction set is available
• CPU_CMOV — Pentium Pro "cmov" instruction is available

🦋 how to actually use her 🦋

you check for multiple features by OR-ing the flags together. iconic behaviour honestly.

so for example, if you wanna know whether the CPU has both an FPU and MMX instructions, you'd do:

if ((cpu_capabilities & (CPU_FPU | CPU_MMX)) ==
    (CPU_FPU | CPU_MMX)) {
   printf("CPU has both an FPU and MMX instructions!\n");
}

see the double-check on both sides of the ==? that's not a typo, that's the vibe check — you're making sure every flag you asked for is actually present, not just one of them 🙈

and like, you can only read this variable after you've called check_cpu() — which, good news, gets automatically called by allegro_init() for you. so if you did your allegro_init(), you're covered, no extra steps required 💅

👑 SEE ALSO 👑

• check_cpu(3)
• cpu_vendor(3)
• cpu_family(3)
• cpu_model(3)
• cpu_capabilities(3) — yes she's referencing herself, main character energy fr fr 💀
• allegro_init(3)

and that's the whole page, bestie 🫶 this was Allegro, version 4.4.3, and we've been reading cpu_capabilities(3) — go forth and check your flags, you ate 💖✨🌈