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e36aeda | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 | // Copyright 2021 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 (
"fmt"
"math/bits"
)
func ExampleAdd32() {
// First number is 33<<32 + 12
n1 := []uint32{33, 12}
// Second number is 21<<32 + 23
n2 := []uint32{21, 23}
// Add them together without producing carry.
d1, carry := bits.Add32(n1[1], n2[1], 0)
d0, _ := bits.Add32(n1[0], n2[0], carry)
nsum := []uint32{d0, d1}
fmt.Printf("%v + %v = %v (carry bit was %v)\n", n1, n2, nsum, carry)
// First number is 1<<32 + 2147483648
n1 = []uint32{1, 0x80000000}
// Second number is 1<<32 + 2147483648
n2 = []uint32{1, 0x80000000}
// Add them together producing carry.
d1, carry = bits.Add32(n1[1], n2[1], 0)
d0, _ = bits.Add32(n1[0], n2[0], carry)
nsum = []uint32{d0, d1}
fmt.Printf("%v + %v = %v (carry bit was %v)\n", n1, n2, nsum, carry)
// Output:
// [33 12] + [21 23] = [54 35] (carry bit was 0)
// [1 2147483648] + [1 2147483648] = [3 0] (carry bit was 1)
}
func ExampleAdd64() {
// First number is 33<<64 + 12
n1 := []uint64{33, 12}
// Second number is 21<<64 + 23
n2 := []uint64{21, 23}
// Add them together without producing carry.
d1, carry := bits.Add64(n1[1], n2[1], 0)
d0, _ := bits.Add64(n1[0], n2[0], carry)
nsum := []uint64{d0, d1}
fmt.Printf("%v + %v = %v (carry bit was %v)\n", n1, n2, nsum, carry)
// First number is 1<<64 + 9223372036854775808
n1 = []uint64{1, 0x8000000000000000}
// Second number is 1<<64 + 9223372036854775808
n2 = []uint64{1, 0x8000000000000000}
// Add them together producing carry.
d1, carry = bits.Add64(n1[1], n2[1], 0)
d0, _ = bits.Add64(n1[0], n2[0], carry)
nsum = []uint64{d0, d1}
fmt.Printf("%v + %v = %v (carry bit was %v)\n", n1, n2, nsum, carry)
// Output:
// [33 12] + [21 23] = [54 35] (carry bit was 0)
// [1 9223372036854775808] + [1 9223372036854775808] = [3 0] (carry bit was 1)
}
func ExampleSub32() {
// First number is 33<<32 + 23
n1 := []uint32{33, 23}
// Second number is 21<<32 + 12
n2 := []uint32{21, 12}
// Sub them together without producing carry.
d1, carry := bits.Sub32(n1[1], n2[1], 0)
d0, _ := bits.Sub32(n1[0], n2[0], carry)
nsum := []uint32{d0, d1}
fmt.Printf("%v - %v = %v (carry bit was %v)\n", n1, n2, nsum, carry)
// First number is 3<<32 + 2147483647
n1 = []uint32{3, 0x7fffffff}
// Second number is 1<<32 + 2147483648
n2 = []uint32{1, 0x80000000}
// Sub them together producing carry.
d1, carry = bits.Sub32(n1[1], n2[1], 0)
d0, _ = bits.Sub32(n1[0], n2[0], carry)
nsum = []uint32{d0, d1}
fmt.Printf("%v - %v = %v (carry bit was %v)\n", n1, n2, nsum, carry)
// Output:
// [33 23] - [21 12] = [12 11] (carry bit was 0)
// [3 2147483647] - [1 2147483648] = [1 4294967295] (carry bit was 1)
}
func ExampleSub64() {
// First number is 33<<64 + 23
n1 := []uint64{33, 23}
// Second number is 21<<64 + 12
n2 := []uint64{21, 12}
// Sub them together without producing carry.
d1, carry := bits.Sub64(n1[1], n2[1], 0)
d0, _ := bits.Sub64(n1[0], n2[0], carry)
nsum := []uint64{d0, d1}
fmt.Printf("%v - %v = %v (carry bit was %v)\n", n1, n2, nsum, carry)
// First number is 3<<64 + 9223372036854775807
n1 = []uint64{3, 0x7fffffffffffffff}
// Second number is 1<<64 + 9223372036854775808
n2 = []uint64{1, 0x8000000000000000}
// Sub them together producing carry.
d1, carry = bits.Sub64(n1[1], n2[1], 0)
d0, _ = bits.Sub64(n1[0], n2[0], carry)
nsum = []uint64{d0, d1}
fmt.Printf("%v - %v = %v (carry bit was %v)\n", n1, n2, nsum, carry)
// Output:
// [33 23] - [21 12] = [12 11] (carry bit was 0)
// [3 9223372036854775807] - [1 9223372036854775808] = [1 18446744073709551615] (carry bit was 1)
}
func ExampleMul32() {
// First number is 0<<32 + 12
n1 := []uint32{0, 12}
// Second number is 0<<32 + 12
n2 := []uint32{0, 12}
// Multiply them together without producing overflow.
hi, lo := bits.Mul32(n1[1], n2[1])
nsum := []uint32{hi, lo}
fmt.Printf("%v * %v = %v\n", n1[1], n2[1], nsum)
// First number is 0<<32 + 2147483648
n1 = []uint32{0, 0x80000000}
// Second number is 0<<32 + 2
n2 = []uint32{0, 2}
// Multiply them together producing overflow.
hi, lo = bits.Mul32(n1[1], n2[1])
nsum = []uint32{hi, lo}
fmt.Printf("%v * %v = %v\n", n1[1], n2[1], nsum)
// Output:
// 12 * 12 = [0 144]
// 2147483648 * 2 = [1 0]
}
func ExampleMul64() {
// First number is 0<<64 + 12
n1 := []uint64{0, 12}
// Second number is 0<<64 + 12
n2 := []uint64{0, 12}
// Multiply them together without producing overflow.
hi, lo := bits.Mul64(n1[1], n2[1])
nsum := []uint64{hi, lo}
fmt.Printf("%v * %v = %v\n", n1[1], n2[1], nsum)
// First number is 0<<64 + 9223372036854775808
n1 = []uint64{0, 0x8000000000000000}
// Second number is 0<<64 + 2
n2 = []uint64{0, 2}
// Multiply them together producing overflow.
hi, lo = bits.Mul64(n1[1], n2[1])
nsum = []uint64{hi, lo}
fmt.Printf("%v * %v = %v\n", n1[1], n2[1], nsum)
// Output:
// 12 * 12 = [0 144]
// 9223372036854775808 * 2 = [1 0]
}
func ExampleDiv32() {
// First number is 0<<32 + 6
n1 := []uint32{0, 6}
// Second number is 0<<32 + 3
n2 := []uint32{0, 3}
// Divide them together.
quo, rem := bits.Div32(n1[0], n1[1], n2[1])
nsum := []uint32{quo, rem}
fmt.Printf("[%v %v] / %v = %v\n", n1[0], n1[1], n2[1], nsum)
// First number is 2<<32 + 2147483648
n1 = []uint32{2, 0x80000000}
// Second number is 0<<32 + 2147483648
n2 = []uint32{0, 0x80000000}
// Divide them together.
quo, rem = bits.Div32(n1[0], n1[1], n2[1])
nsum = []uint32{quo, rem}
fmt.Printf("[%v %v] / %v = %v\n", n1[0], n1[1], n2[1], nsum)
// Output:
// [0 6] / 3 = [2 0]
// [2 2147483648] / 2147483648 = [5 0]
}
func ExampleDiv64() {
// First number is 0<<64 + 6
n1 := []uint64{0, 6}
// Second number is 0<<64 + 3
n2 := []uint64{0, 3}
// Divide them together.
quo, rem := bits.Div64(n1[0], n1[1], n2[1])
nsum := []uint64{quo, rem}
fmt.Printf("[%v %v] / %v = %v\n", n1[0], n1[1], n2[1], nsum)
// First number is 2<<64 + 9223372036854775808
n1 = []uint64{2, 0x8000000000000000}
// Second number is 0<<64 + 9223372036854775808
n2 = []uint64{0, 0x8000000000000000}
// Divide them together.
quo, rem = bits.Div64(n1[0], n1[1], n2[1])
nsum = []uint64{quo, rem}
fmt.Printf("[%v %v] / %v = %v\n", n1[0], n1[1], n2[1], nsum)
// Output:
// [0 6] / 3 = [2 0]
// [2 9223372036854775808] / 9223372036854775808 = [5 0]
}
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