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const std = @import("std");
const builtin = @import("builtin");
const native_arch = builtin.cpu.arch;
const expect = std.testing.expect;
// Functions are declared like this
fn add(a: i8, b: i8) i8 {
if (a == 0) {
return b;
}
return a + b;
}
// The export specifier makes a function externally visible in the generated
// object file, and makes it use the C ABI.
export fn sub(a: i8, b: i8) i8 {
return a - b;
}
// The extern specifier is used to declare a function that will be resolved
// at link time, when linking statically, or at runtime, when linking
// dynamically. The quoted identifier after the extern keyword specifies
// the library that has the function. (e.g. "c" -> libc.so)
// The callconv specifier changes the calling convention of the function.
extern "kernel32" fn ExitProcess(exit_code: u32) callconv(.winapi) noreturn;
extern "c" fn atan2(a: f64, b: f64) f64;
// The @branchHint builtin can be used to tell the optimizer that a function is rarely called ("cold").
fn abort() noreturn {
@branchHint(.cold);
while (true) {}
}
// The naked calling convention makes a function not have any function prologue or epilogue.
// This can be useful when integrating with assembly.
fn _start() callconv(.naked) noreturn {
abort();
}
// The inline calling convention forces a function to be inlined at all call sites.
// If the function cannot be inlined, it is a compile-time error.
inline fn shiftLeftOne(a: u32) u32 {
return a << 1;
}
// The pub specifier allows the function to be visible when importing.
// Another file can use @import and call sub2
pub fn sub2(a: i8, b: i8) i8 {
return a - b;
}
// Function pointers are prefixed with `*const `.
const Call2Op = *const fn (a: i8, b: i8) i8;
fn doOp(fnCall: Call2Op, op1: i8, op2: i8) i8 {
return fnCall(op1, op2);
}
test "function" {
try expect(doOp(add, 5, 6) == 11);
try expect(doOp(sub2, 5, 6) == -1);
}
// test
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