| // Copyright 2017 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package bits_test |
| |
| import ( |
| . "math/bits" |
| "testing" |
| "unsafe" |
| ) |
| |
| func TestUintSize(t *testing.T) { |
| var x uint |
| if want := unsafe.Sizeof(x) * 8; UintSize != want { |
| t.Fatalf("UintSize = %d; want %d", UintSize, want) |
| } |
| } |
| |
| func TestLeadingZeros(t *testing.T) { |
| for i := 0; i < 256; i++ { |
| nlz := tab[i].nlz |
| for k := 0; k < 64-8; k++ { |
| x := uint64(i) << uint(k) |
| if x <= 1<<8-1 { |
| got := LeadingZeros8(uint8(x)) |
| want := nlz - k + (8 - 8) |
| if x == 0 { |
| want = 8 |
| } |
| if got != want { |
| t.Fatalf("LeadingZeros8(%#02x) == %d; want %d", x, got, want) |
| } |
| } |
| |
| if x <= 1<<16-1 { |
| got := LeadingZeros16(uint16(x)) |
| want := nlz - k + (16 - 8) |
| if x == 0 { |
| want = 16 |
| } |
| if got != want { |
| t.Fatalf("LeadingZeros16(%#04x) == %d; want %d", x, got, want) |
| } |
| } |
| |
| if x <= 1<<32-1 { |
| got := LeadingZeros32(uint32(x)) |
| want := nlz - k + (32 - 8) |
| if x == 0 { |
| want = 32 |
| } |
| if got != want { |
| t.Fatalf("LeadingZeros32(%#08x) == %d; want %d", x, got, want) |
| } |
| if UintSize == 32 { |
| got = LeadingZeros(uint(x)) |
| if got != want { |
| t.Fatalf("LeadingZeros(%#08x) == %d; want %d", x, got, want) |
| } |
| } |
| } |
| |
| if x <= 1<<64-1 { |
| got := LeadingZeros64(uint64(x)) |
| want := nlz - k + (64 - 8) |
| if x == 0 { |
| want = 64 |
| } |
| if got != want { |
| t.Fatalf("LeadingZeros64(%#016x) == %d; want %d", x, got, want) |
| } |
| if UintSize == 64 { |
| got = LeadingZeros(uint(x)) |
| if got != want { |
| t.Fatalf("LeadingZeros(%#016x) == %d; want %d", x, got, want) |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| // Exported (global) variable serving as input for some |
| // of the benchmarks to ensure side-effect free calls |
| // are not optimized away. |
| var Input uint64 = DeBruijn64 |
| |
| // Exported (global) variable to store function results |
| // during benchmarking to ensure side-effect free calls |
| // are not optimized away. |
| var Output int |
| |
| func BenchmarkLeadingZeros(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += LeadingZeros(uint(Input) >> (uint(i) % UintSize)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkLeadingZeros8(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += LeadingZeros8(uint8(Input) >> (uint(i) % 8)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkLeadingZeros16(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += LeadingZeros16(uint16(Input) >> (uint(i) % 16)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkLeadingZeros32(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += LeadingZeros32(uint32(Input) >> (uint(i) % 32)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkLeadingZeros64(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += LeadingZeros64(uint64(Input) >> (uint(i) % 64)) |
| } |
| Output = s |
| } |
| |
| func TestTrailingZeros(t *testing.T) { |
| for i := 0; i < 256; i++ { |
| ntz := tab[i].ntz |
| for k := 0; k < 64-8; k++ { |
| x := uint64(i) << uint(k) |
| want := ntz + k |
| if x <= 1<<8-1 { |
| got := TrailingZeros8(uint8(x)) |
| if x == 0 { |
| want = 8 |
| } |
| if got != want { |
| t.Fatalf("TrailingZeros8(%#02x) == %d; want %d", x, got, want) |
| } |
| } |
| |
| if x <= 1<<16-1 { |
| got := TrailingZeros16(uint16(x)) |
| if x == 0 { |
| want = 16 |
| } |
| if got != want { |
| t.Fatalf("TrailingZeros16(%#04x) == %d; want %d", x, got, want) |
| } |
| } |
| |
| if x <= 1<<32-1 { |
| got := TrailingZeros32(uint32(x)) |
| if x == 0 { |
| want = 32 |
| } |
| if got != want { |
| t.Fatalf("TrailingZeros32(%#08x) == %d; want %d", x, got, want) |
| } |
| if UintSize == 32 { |
| got = TrailingZeros(uint(x)) |
| if got != want { |
| t.Fatalf("TrailingZeros(%#08x) == %d; want %d", x, got, want) |
| } |
| } |
| } |
| |
| if x <= 1<<64-1 { |
| got := TrailingZeros64(uint64(x)) |
| if x == 0 { |
| want = 64 |
| } |
| if got != want { |
| t.Fatalf("TrailingZeros64(%#016x) == %d; want %d", x, got, want) |
| } |
| if UintSize == 64 { |
| got = TrailingZeros(uint(x)) |
| if got != want { |
| t.Fatalf("TrailingZeros(%#016x) == %d; want %d", x, got, want) |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| func BenchmarkTrailingZeros(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += TrailingZeros(uint(Input) << (uint(i) % UintSize)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkTrailingZeros8(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += TrailingZeros8(uint8(Input) << (uint(i) % 8)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkTrailingZeros16(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += TrailingZeros16(uint16(Input) << (uint(i) % 16)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkTrailingZeros32(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += TrailingZeros32(uint32(Input) << (uint(i) % 32)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkTrailingZeros64(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += TrailingZeros64(uint64(Input) << (uint(i) % 64)) |
| } |
| Output = s |
| } |
| |
| func TestOnesCount(t *testing.T) { |
| var x uint64 |
| for i := 0; i <= 64; i++ { |
| testOnesCount(t, x, i) |
| x = x<<1 | 1 |
| } |
| |
| for i := 64; i >= 0; i-- { |
| testOnesCount(t, x, i) |
| x = x << 1 |
| } |
| |
| for i := 0; i < 256; i++ { |
| for k := 0; k < 64-8; k++ { |
| testOnesCount(t, uint64(i)<<uint(k), tab[i].pop) |
| } |
| } |
| } |
| |
| func testOnesCount(t *testing.T, x uint64, want int) { |
| if x <= 1<<8-1 { |
| got := OnesCount8(uint8(x)) |
| if got != want { |
| t.Fatalf("OnesCount8(%#02x) == %d; want %d", uint8(x), got, want) |
| } |
| } |
| |
| if x <= 1<<16-1 { |
| got := OnesCount16(uint16(x)) |
| if got != want { |
| t.Fatalf("OnesCount16(%#04x) == %d; want %d", uint16(x), got, want) |
| } |
| } |
| |
| if x <= 1<<32-1 { |
| got := OnesCount32(uint32(x)) |
| if got != want { |
| t.Fatalf("OnesCount32(%#08x) == %d; want %d", uint32(x), got, want) |
| } |
| if UintSize == 32 { |
| got = OnesCount(uint(x)) |
| if got != want { |
| t.Fatalf("OnesCount(%#08x) == %d; want %d", uint32(x), got, want) |
| } |
| } |
| } |
| |
| if x <= 1<<64-1 { |
| got := OnesCount64(uint64(x)) |
| if got != want { |
| t.Fatalf("OnesCount64(%#016x) == %d; want %d", x, got, want) |
| } |
| if UintSize == 64 { |
| got = OnesCount(uint(x)) |
| if got != want { |
| t.Fatalf("OnesCount(%#016x) == %d; want %d", x, got, want) |
| } |
| } |
| } |
| } |
| |
| func BenchmarkOnesCount(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += OnesCount(uint(Input)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkOnesCount8(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += OnesCount8(uint8(Input)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkOnesCount16(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += OnesCount16(uint16(Input)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkOnesCount32(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += OnesCount32(uint32(Input)) |
| } |
| Output = s |
| } |
| |
| func BenchmarkOnesCount64(b *testing.B) { |
| var s int |
| for i := 0; i < b.N; i++ { |
| s += OnesCount64(uint64(Input)) |
| } |
| Output = s |
| } |
| |
| func TestRotateLeft(t *testing.T) { |
| var m uint64 = DeBruijn64 |
| |
| for k := uint(0); k < 128; k++ { |
| x8 := uint8(m) |
| got8 := RotateLeft8(x8, int(k)) |
| want8 := x8<<(k&0x7) | x8>>(8-k&0x7) |
| if got8 != want8 { |
| t.Fatalf("RotateLeft8(%#02x, %d) == %#02x; want %#02x", x8, k, got8, want8) |
| } |
| got8 = RotateLeft8(want8, -int(k)) |
| if got8 != x8 { |
| t.Fatalf("RotateLeft8(%#02x, -%d) == %#02x; want %#02x", want8, k, got8, x8) |
| } |
| |
| x16 := uint16(m) |
| got16 := RotateLeft16(x16, int(k)) |
| want16 := x16<<(k&0xf) | x16>>(16-k&0xf) |
| if got16 != want16 { |
| t.Fatalf("RotateLeft16(%#04x, %d) == %#04x; want %#04x", x16, k, got16, want16) |
| } |
| got16 = RotateLeft16(want16, -int(k)) |
| if got16 != x16 { |
| t.Fatalf("RotateLeft16(%#04x, -%d) == %#04x; want %#04x", want16, k, got16, x16) |
| } |
| |
| x32 := uint32(m) |
| got32 := RotateLeft32(x32, int(k)) |
| want32 := x32<<(k&0x1f) | x32>>(32-k&0x1f) |
| if got32 != want32 { |
| t.Fatalf("RotateLeft32(%#08x, %d) == %#08x; want %#08x", x32, k, got32, want32) |
| } |
| got32 = RotateLeft32(want32, -int(k)) |
| if got32 != x32 { |
| t.Fatalf("RotateLeft32(%#08x, -%d) == %#08x; want %#08x", want32, k, got32, x32) |
| } |
| if UintSize == 32 { |
| x := uint(m) |
| got := RotateLeft(x, int(k)) |
| want := x<<(k&0x1f) | x>>(32-k&0x1f) |
| if got != want { |
| t.Fatalf("RotateLeft(%#08x, %d) == %#08x; want %#08x", x, k, got, want) |
| } |
| got = RotateLeft(want, -int(k)) |
| if got != x { |
| t.Fatalf("RotateLeft(%#08x, -%d) == %#08x; want %#08x", want, k, got, x) |
| } |
| } |
| |
| x64 := uint64(m) |
| got64 := RotateLeft64(x64, int(k)) |
| want64 := x64<<(k&0x3f) | x64>>(64-k&0x3f) |
| if got64 != want64 { |
| t.Fatalf("RotateLeft64(%#016x, %d) == %#016x; want %#016x", x64, k, got64, want64) |
| } |
| got64 = RotateLeft64(want64, -int(k)) |
| if got64 != x64 { |
| t.Fatalf("RotateLeft64(%#016x, -%d) == %#016x; want %#016x", want64, k, got64, x64) |
| } |
| if UintSize == 64 { |
| x := uint(m) |
| got := RotateLeft(x, int(k)) |
| want := x<<(k&0x3f) | x>>(64-k&0x3f) |
| if got != want { |
| t.Fatalf("RotateLeft(%#016x, %d) == %#016x; want %#016x", x, k, got, want) |
| } |
| got = RotateLeft(want, -int(k)) |
| if got != x { |
| t.Fatalf("RotateLeft(%#08x, -%d) == %#08x; want %#08x", want, k, got, x) |
| } |
| } |
| } |
| } |
| |
| func BenchmarkRotateLeft(b *testing.B) { |
| var s uint |
| for i := 0; i < b.N; i++ { |
| s += RotateLeft(uint(Input), i) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkRotateLeft8(b *testing.B) { |
| var s uint8 |
| for i := 0; i < b.N; i++ { |
| s += RotateLeft8(uint8(Input), i) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkRotateLeft16(b *testing.B) { |
| var s uint16 |
| for i := 0; i < b.N; i++ { |
| s += RotateLeft16(uint16(Input), i) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkRotateLeft32(b *testing.B) { |
| var s uint32 |
| for i := 0; i < b.N; i++ { |
| s += RotateLeft32(uint32(Input), i) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkRotateLeft64(b *testing.B) { |
| var s uint64 |
| for i := 0; i < b.N; i++ { |
| s += RotateLeft64(uint64(Input), i) |
| } |
| Output = int(s) |
| } |
| |
| func TestReverse(t *testing.T) { |
| // test each bit |
| for i := uint(0); i < 64; i++ { |
| testReverse(t, uint64(1)<<i, uint64(1)<<(63-i)) |
| } |
| |
| // test a few patterns |
| for _, test := range []struct { |
| x, r uint64 |
| }{ |
| {0, 0}, |
| {0x1, 0x8 << 60}, |
| {0x2, 0x4 << 60}, |
| {0x3, 0xc << 60}, |
| {0x4, 0x2 << 60}, |
| {0x5, 0xa << 60}, |
| {0x6, 0x6 << 60}, |
| {0x7, 0xe << 60}, |
| {0x8, 0x1 << 60}, |
| {0x9, 0x9 << 60}, |
| {0xa, 0x5 << 60}, |
| {0xb, 0xd << 60}, |
| {0xc, 0x3 << 60}, |
| {0xd, 0xb << 60}, |
| {0xe, 0x7 << 60}, |
| {0xf, 0xf << 60}, |
| {0x5686487, 0xe12616a000000000}, |
| {0x0123456789abcdef, 0xf7b3d591e6a2c480}, |
| } { |
| testReverse(t, test.x, test.r) |
| testReverse(t, test.r, test.x) |
| } |
| } |
| |
| func testReverse(t *testing.T, x64, want64 uint64) { |
| x8 := uint8(x64) |
| got8 := Reverse8(x8) |
| want8 := uint8(want64 >> (64 - 8)) |
| if got8 != want8 { |
| t.Fatalf("Reverse8(%#02x) == %#02x; want %#02x", x8, got8, want8) |
| } |
| |
| x16 := uint16(x64) |
| got16 := Reverse16(x16) |
| want16 := uint16(want64 >> (64 - 16)) |
| if got16 != want16 { |
| t.Fatalf("Reverse16(%#04x) == %#04x; want %#04x", x16, got16, want16) |
| } |
| |
| x32 := uint32(x64) |
| got32 := Reverse32(x32) |
| want32 := uint32(want64 >> (64 - 32)) |
| if got32 != want32 { |
| t.Fatalf("Reverse32(%#08x) == %#08x; want %#08x", x32, got32, want32) |
| } |
| if UintSize == 32 { |
| x := uint(x32) |
| got := Reverse(x) |
| want := uint(want32) |
| if got != want { |
| t.Fatalf("Reverse(%#08x) == %#08x; want %#08x", x, got, want) |
| } |
| } |
| |
| got64 := Reverse64(x64) |
| if got64 != want64 { |
| t.Fatalf("Reverse64(%#016x) == %#016x; want %#016x", x64, got64, want64) |
| } |
| if UintSize == 64 { |
| x := uint(x64) |
| got := Reverse(x) |
| want := uint(want64) |
| if got != want { |
| t.Fatalf("Reverse(%#08x) == %#016x; want %#016x", x, got, want) |
| } |
| } |
| } |
| |
| func BenchmarkReverse(b *testing.B) { |
| var s uint |
| for i := 0; i < b.N; i++ { |
| s += Reverse(uint(i)) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkReverse8(b *testing.B) { |
| var s uint8 |
| for i := 0; i < b.N; i++ { |
| s += Reverse8(uint8(i)) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkReverse16(b *testing.B) { |
| var s uint16 |
| for i := 0; i < b.N; i++ { |
| s += Reverse16(uint16(i)) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkReverse32(b *testing.B) { |
| var s uint32 |
| for i := 0; i < b.N; i++ { |
| s += Reverse32(uint32(i)) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkReverse64(b *testing.B) { |
| var s uint64 |
| for i := 0; i < b.N; i++ { |
| s += Reverse64(uint64(i)) |
| } |
| Output = int(s) |
| } |
| |
| func TestReverseBytes(t *testing.T) { |
| for _, test := range []struct { |
| x, r uint64 |
| }{ |
| {0, 0}, |
| {0x01, 0x01 << 56}, |
| {0x0123, 0x2301 << 48}, |
| {0x012345, 0x452301 << 40}, |
| {0x01234567, 0x67452301 << 32}, |
| {0x0123456789, 0x8967452301 << 24}, |
| {0x0123456789ab, 0xab8967452301 << 16}, |
| {0x0123456789abcd, 0xcdab8967452301 << 8}, |
| {0x0123456789abcdef, 0xefcdab8967452301 << 0}, |
| } { |
| testReverseBytes(t, test.x, test.r) |
| testReverseBytes(t, test.r, test.x) |
| } |
| } |
| |
| func testReverseBytes(t *testing.T, x64, want64 uint64) { |
| x16 := uint16(x64) |
| got16 := ReverseBytes16(x16) |
| want16 := uint16(want64 >> (64 - 16)) |
| if got16 != want16 { |
| t.Fatalf("ReverseBytes16(%#04x) == %#04x; want %#04x", x16, got16, want16) |
| } |
| |
| x32 := uint32(x64) |
| got32 := ReverseBytes32(x32) |
| want32 := uint32(want64 >> (64 - 32)) |
| if got32 != want32 { |
| t.Fatalf("ReverseBytes32(%#08x) == %#08x; want %#08x", x32, got32, want32) |
| } |
| if UintSize == 32 { |
| x := uint(x32) |
| got := ReverseBytes(x) |
| want := uint(want32) |
| if got != want { |
| t.Fatalf("ReverseBytes(%#08x) == %#08x; want %#08x", x, got, want) |
| } |
| } |
| |
| got64 := ReverseBytes64(x64) |
| if got64 != want64 { |
| t.Fatalf("ReverseBytes64(%#016x) == %#016x; want %#016x", x64, got64, want64) |
| } |
| if UintSize == 64 { |
| x := uint(x64) |
| got := ReverseBytes(x) |
| want := uint(want64) |
| if got != want { |
| t.Fatalf("ReverseBytes(%#016x) == %#016x; want %#016x", x, got, want) |
| } |
| } |
| } |
| |
| func BenchmarkReverseBytes(b *testing.B) { |
| var s uint |
| for i := 0; i < b.N; i++ { |
| s += ReverseBytes(uint(i)) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkReverseBytes16(b *testing.B) { |
| var s uint16 |
| for i := 0; i < b.N; i++ { |
| s += ReverseBytes16(uint16(i)) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkReverseBytes32(b *testing.B) { |
| var s uint32 |
| for i := 0; i < b.N; i++ { |
| s += ReverseBytes32(uint32(i)) |
| } |
| Output = int(s) |
| } |
| |
| func BenchmarkReverseBytes64(b *testing.B) { |
| var s uint64 |
| for i := 0; i < b.N; i++ { |
| s += ReverseBytes64(uint64(i)) |
| } |
| Output = int(s) |
| } |
| |
| func TestLen(t *testing.T) { |
| for i := 0; i < 256; i++ { |
| len := 8 - tab[i].nlz |
| for k := 0; k < 64-8; k++ { |
| x := uint64(i) << uint(k) |
| want := 0 |
| if x != 0 { |
| want = len + k |
| } |
| if x <= 1<<8-1 { |
| got := Len8(uint8(x)) |
| if got != want { |
| t.Fatalf("Len8(%#02x) == %d; want %d", x, got, want) |
| } |
| } |
| |
| if x <= 1<<16-1 { |
| got := Len16(uint16(x)) |
| if got != want { |
| t.Fatalf("Len16(%#04x) == %d; want %d", x, got, want) |
| } |
| } |
| |
| if x <= 1<<32-1 { |
| got := Len32(uint32(x)) |
| if got != want { |
| t.Fatalf("Len32(%#08x) == %d; want %d", x, got, want) |
| } |
| if UintSize == 32 { |
| got := Len(uint(x)) |
| if got != want { |
| t.Fatalf("Len(%#08x) == %d; want %d", x, got, want) |
| } |
| } |
| } |
| |
| if x <= 1<<64-1 { |
| got := Len64(uint64(x)) |
| if got != want { |
| t.Fatalf("Len64(%#016x) == %d; want %d", x, got, want) |
| } |
| if UintSize == 64 { |
| got := Len(uint(x)) |
| if got != want { |
| t.Fatalf("Len(%#016x) == %d; want %d", x, got, want) |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| // ---------------------------------------------------------------------------- |
| // Testing support |
| |
| type entry = struct { |
| nlz, ntz, pop int |
| } |
| |
| // tab contains results for all uint8 values |
| var tab [256]entry |
| |
| func init() { |
| tab[0] = entry{8, 8, 0} |
| for i := 1; i < len(tab); i++ { |
| // nlz |
| x := i // x != 0 |
| n := 0 |
| for x&0x80 == 0 { |
| n++ |
| x <<= 1 |
| } |
| tab[i].nlz = n |
| |
| // ntz |
| x = i // x != 0 |
| n = 0 |
| for x&1 == 0 { |
| n++ |
| x >>= 1 |
| } |
| tab[i].ntz = n |
| |
| // pop |
| x = i // x != 0 |
| n = 0 |
| for x != 0 { |
| n += int(x & 1) |
| x >>= 1 |
| } |
| tab[i].pop = n |
| } |
| } |
