zig/lib/compiler_rt/popcountti2_test.zig
2023-11-19 09:55:07 +00:00

36 lines
1.1 KiB
Zig

const std = @import("std");
const popcount = @import("popcount.zig");
const testing = std.testing;
fn popcountti2Naive(a: i128) i32 {
var x = a;
var r: i32 = 0;
while (x != 0) : (x = @as(i128, @bitCast(@as(u128, @bitCast(x)) >> 1))) {
r += @as(i32, @intCast(x & 1));
}
return r;
}
fn test__popcountti2(a: i128) !void {
const x = popcount.__popcountti2(a);
const expected = popcountti2Naive(a);
try testing.expectEqual(expected, x);
}
test "popcountti2" {
try test__popcountti2(0);
try test__popcountti2(1);
try test__popcountti2(2);
try test__popcountti2(@as(i128, @bitCast(@as(u128, 0xffffffff_ffffffff_ffffffff_fffffffd))));
try test__popcountti2(@as(i128, @bitCast(@as(u128, 0xffffffff_ffffffff_ffffffff_fffffffe))));
try test__popcountti2(@as(i128, @bitCast(@as(u128, 0xffffffff_ffffffff_ffffffff_ffffffff))));
const RndGen = std.rand.DefaultPrng;
var rnd = RndGen.init(42);
var i: u32 = 0;
while (i < 10_000) : (i += 1) {
const rand_num = rnd.random().int(i128);
try test__popcountti2(rand_num);
}
}