使用golang中的位移将位从32位无符号整数中取出

I have a 32bit unsigned integer and I want to divide it in 3 uint16 values. I want first 15bits, then 2 bits and then last 15 bits.

I am trying something like -

val >> 17
val >> 2
val >> 15

apart from first value, other 2 are not right and I know that but now able to figure out how to fix that?

Go play ground

For example,

package main

import "fmt"

func decode(bits uint32) (uint16, uint16, uint16) {
    // first 15bits, then 2 bits and then last 15 bits.
    const mask2 = ^uint32(0) >> (32 - 2)
    const mask15 = ^uint32(0) >> (32 - 15)
    b1 := uint16(bits >> (32 - 15))
    b2 := uint16(bits >> (32 - 15 - 2) & mask2)
    b3 := uint16(bits & mask15)
    return b1, b2, b3
}

func main() {
    b := uint32(4628440)
    b1, b2, b3 := decode(b)
    fmt.Printf("%032b %015b %02b %015b
", b, b1, b2, b3)
    fmt.Printf("%d %d-%d-%d
", b, b1, b2, b3)
}

Output:

00000000010001101001111111011000 000000000100011 01 001111111011000
4628440 35-1-8152

A helper function to extract a range of bits makes this easy to understand (and test).

package main

import "fmt"

// extractUint16 extracts n bits of a from the given offset.
func extractUint16(a uint32, offset, n uint) uint16 {
    return uint16((a >> offset) & (1<<n - 1))
}

func main() {
    input := uint32(4628440)
    a := extractUint16(input, 17, 15)
    b := extractUint16(input, 15, 2)
    c := extractUint16(input, 0, 15)
    fmt.Println(a, b, c)
}