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e4c053f047
- use Bit Twiddling Hacks: Compute parity in parallel - test cases derived from popcount.zig - tests: compare naive approach 10_000 times with random numbers created from naive seed 42 - compiler_rt.zig: sort by LLVM builtin order and add comments to improve structure See #1290
36 lines
1020 B
Zig
36 lines
1020 B
Zig
const parity = @import("parity.zig");
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const testing = @import("std").testing;
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fn paritydi2Naive(a: i64) i32 {
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var x = @bitCast(u64, a);
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var has_parity: bool = false;
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while (x > 0) {
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has_parity = !has_parity;
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x = x & (x - 1);
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}
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return @intCast(i32, @boolToInt(has_parity));
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}
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fn test__paritydi2(a: i64) !void {
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var x = parity.__paritydi2(a);
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var expected: i64 = paritydi2Naive(a);
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try testing.expectEqual(expected, x);
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}
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test "paritydi2" {
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try test__paritydi2(0);
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try test__paritydi2(1);
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try test__paritydi2(2);
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try test__paritydi2(@bitCast(i64, @as(u64, 0xffffffff_fffffffd)));
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try test__paritydi2(@bitCast(i64, @as(u64, 0xffffffff_fffffffe)));
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try test__paritydi2(@bitCast(i64, @as(u64, 0xffffffff_ffffffff)));
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const RndGen = @import("std").rand.DefaultPrng;
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var rnd = RndGen.init(42);
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var i: u32 = 0;
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while (i < 10_000) : (i += 1) {
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var rand_num = rnd.random().int(i64);
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try test__paritydi2(rand_num);
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}
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}
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