How to convert between big and small endian in golang

In computers, the byte order of the CPU is divided into two types: Big-Endian and Little-Endian. Big-endian byte order stores the highest-order byte at the lowest memory address and the lowest-order byte at the highest memory address. Little-endian byte order does the opposite, storing the lowest-order byte at the lowest memory address and the highest-order byte at the highest memory address. Sections are saved at the highest memory address.

Golang provides some convenient methods to convert between big endian and little endian. This article will introduce the big and small endian conversion method in Golang.

Implementation method

Conventional method

In Golang, you can use some functions to achieve byte order conversion. For example, the encoding/binary package provides the following functions:

• binary.BigEndian.Uint16
• binary.BigEndian. Uint32
• binary.BigEndian.Uint64
• ##binary.BigEndian.PutUint16
##binary.BigEndian .PutUint32
binary.BigEndian.PutUint64
These functions convert a primitive type data value to or from big endian. Converts the data value back to the original type in big-endian byte order.

At the same time, the

encoding/binary

package also provides a little-endian byte order function similar to the above function:

##binary.LittleEndian.Uint16

• binary.LittleEndian.Uint32
• binary.LittleEndian.Uint64
• binary.LittleEndian. PutUint16
• binary.LittleEndian.PutUint32
• binary.LittleEndian.PutUint64
• These functions can Converts a data value of a primitive type to or from little-endian byte order.

Suppose we have an integer value of type uint16 and want to convert it from big endian to little endian. At this time we can use the following code to achieve:

var big uint16 = 0x1234
var little uint16 = binary.LittleEndian.Uint16([]byte{byte(big >> 8), byte(big)})

Similarly, if we want to convert an integer value of type uint16 from little-endian byte order to big-endian byte order, we can use the following code:

var little uint16 = 0x1234
var big uint16 = binary.BigEndian.Uint16([]byte{byte(little >> 8), byte(little)})

Optimization method

In the process of implementing endian conversion, we can use different optimization methods for different types of data to improve performance.

Data type less than or equal to 2 bytes: For this type of data, we can perform bit operations directly without using the

encoding/binary
• package. function. For example, if we want to convert an integer value of type uint16 from big-endian to little-endian, we can use the following code:

  var big uint16 = 0x1234 
  var little uint16 = (big << 8) | (big >> 8)

  Greater than 2 bytes Data type: For this type of data, we can convert it by using the tools provided by the
unsafe.Pointer
• and

  reflect packages to improve performance. For example, if we want to convert an integer value of type uint32 from big-endian to little-endian, we can use the following code:

  value := uint32(0x12345678)
  var arr [4]byte
  *(*uint32)(unsafe.Pointer(&arr[0])) = value
  reflect.Reverse(reflect.ValueOf(arr[:]).Slice(0, 4))
  little := *(*uint32)(unsafe.Pointer(&arr[0]))

  will # A data value of type ##uint32
  value
  • is converted to a byte array arr. Use the tool function Reverse in the
  reflect
  • package to reverse the byte array arr to convert it from big-endian byte order It is little endian. Convert the byte array arr to a data value of type
  uint32
  • little.
  Summary
This article introduces two ways to implement big-endian conversion in Golang: the conventional method and the optimized method. The conventional method is implemented through the functions provided by the

encoding/binary

package and is more readable; the optimized method can improve conversion performance in some specific scenarios. In practical applications, it is necessary to choose how to convert different data types.

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