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const std = @import("std");
const builtin = @import("builtin");
const expect = std.testing.expect;
const native_endian = builtin.target.cpu.arch.endian();
test "reinterpret bytes as integer with nonzero offset" {
if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
try testReinterpretBytesAsInteger();
comptime try testReinterpretBytesAsInteger();
}
fn testReinterpretBytesAsInteger() !void {
const bytes = "\x12\x34\x56\x78\xab";
const expected = switch (native_endian) {
.Little => 0xab785634,
.Big => 0x345678ab,
};
try expect(@ptrCast(*align(1) const u32, bytes[1..5]).* == expected);
}
test "reinterpret bytes of an array into an extern struct" {
if (builtin.zig_backend != .stage1) return error.SkipZigTest; // TODO
try testReinterpretBytesAsExternStruct();
comptime try testReinterpretBytesAsExternStruct();
}
fn testReinterpretBytesAsExternStruct() !void {
var bytes align(2) = [_]u8{ 1, 2, 3, 4, 5, 6 };
const S = extern struct {
a: u8,
b: u16,
c: u8,
};
var ptr = @ptrCast(*const S, &bytes);
var val = ptr.c;
try expect(val == 5);
}
test "reinterpret struct field at comptime" {
if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
const numNative = comptime Bytes.init(0x12345678);
if (native_endian != .Little) {
try expect(std.mem.eql(u8, &[_]u8{ 0x12, 0x34, 0x56, 0x78 }, &numNative.bytes));
} else {
try expect(std.mem.eql(u8, &[_]u8{ 0x78, 0x56, 0x34, 0x12 }, &numNative.bytes));
}
}
const Bytes = struct {
bytes: [4]u8,
pub fn init(v: u32) Bytes {
var res: Bytes = undefined;
@ptrCast(*align(1) u32, &res.bytes).* = v;
return res;
}
};
test "comptime ptrcast keeps larger alignment" {
comptime {
const a: u32 = 1234;
const p = @ptrCast([*]const u8, &a);
try expect(@TypeOf(p) == [*]align(@alignOf(u32)) const u8);
}
}
test "implicit optional pointer to optional anyopaque pointer" {
if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
var buf: [4]u8 = "aoeu".*;
var x: ?[*]u8 = &buf;
var y: ?*anyopaque = x;
var z = @ptrCast(*[4]u8, y);
try expect(std.mem.eql(u8, z, "aoeu"));
}
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