Usage of `extern "C" 'type' NASM_function_name(int threadID); in carbon

[FCLC]

Hi guys/gals/NB-pals!

Currently going through the docs, trying to wrap my mind around if I should be using the same extern style as used in CPP to link to hand optimized SIMD/assembly functions.

Currently you'd do something like

extern "C" 'type' NASM_function_name(int threadID);

where NASM_function_name is something along the lines of:

NASM_function_name:
    push rbx
    push rdi
    push rsi
    push rbp
    push r11
    push r8
    push r9
    push r10
    push r12

/// math goes here

    dec r12
    jnz .LoopHead

    pop r12
    pop r10
    pop r9
    pop r8
    pop r11
    pop rbp
    pop rsi
    pop rdi
    pop rbx
    ret

in C++.

you'd have NASM/yasm compile the *.asm and link via your makefile.

what does that look like for carbon? what is the expected workflow in carbon?

[chandlerc]

Not sure what syntax we'll use for declaring external C functions when there isn't a C header to import, but yeah, we'll want to add some explicit syntax for that. Not sure its a high priority to design it until the rest of the interop is working, but then we'll probably work on some way of achieving this.

[FCLC]

Glad to hear! Project is interesting for certain, just hoping it doesn't go the way of https://killedbygoogle.com