zig

test_functions.zig (1948B) - Raw

---

 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