在NETMF转换'浮动'到'字节[4]“再回到”浮动“ [英] Converting 'float' to 'byte[4]' and back to 'float' in NETMF
问题描述
什么是一个浮动
转换为字节[4]
然后再返回到一个浮动的最佳方式'?
What's the best way to convert a float
to a byte[4]
and then back to a 'float'?
我在C#中 NETMF 这样做,所以没有 BitConverter
供我使用。
I am doing this in C# NETMF, so there is no BitConverter
available for my use.
推荐答案
我修改从的 BitConverter 类=HTTP://forums.netduino .COM /的index.php?/主题/ 308-bitconverter相对=nofollow>一个Netduino实现允许字节序规范(这不是最好的方法,但它的作品)。如果字节数组是通过网络发送,我会使用大尾端
。只是一个提醒,不安全
不NETMF正式支持。
I've modified the BitConverter
class from a Netduino implementation to allow endianness specification (it's not the "best way", but it works). If the byte array is sent over the network, I would use BigEndian
. Just a reminder that unsafe
is not officially supported in NETMF.
using System;
using System.Diagnostics;
namespace netduino
{
public static class BitConverter
{
public static byte[] GetBytes(uint value)
{
return new byte[4] {
(byte)(value & 0xFF),
(byte)((value >> 8) & 0xFF),
(byte)((value >> 16) & 0xFF),
(byte)((value >> 24) & 0xFF) };
}
public static unsafe byte[] GetBytes(float value)
{
uint val = *((uint*)&value);
return GetBytes(val);
}
public static unsafe byte[] GetBytes(float value, ByteOrder order)
{
byte[] bytes = GetBytes(value);
if (order != ByteOrder.LittleEndian)
{
System.Array.Reverse(bytes);
}
return bytes;
}
public static uint ToUInt32(byte[] value, int index)
{
return (uint)(
value[0 + index] << 0 |
value[1 + index] << 8 |
value[2 + index] << 16 |
value[3 + index] << 24);
}
public static unsafe float ToSingle(byte[] value, int index)
{
uint i = ToUInt32(value, index);
return *(((float*)&i));
}
public static unsafe float ToSingle(byte[] value, int index, ByteOrder order)
{
if (order != ByteOrder.LittleEndian)
{
System.Array.Reverse(value, index, value.Length);
}
return ToSingle(value, index);
}
public enum ByteOrder
{
LittleEndian,
BigEndian
}
static public bool IsLittleEndian
{
get
{
unsafe
{
int i = 1;
char* p = (char*)&i;
return (p[0] == 1);
}
}
}
}
}
namespace BitConverterTest
{
class Program
{
static void Main(string[] args)
{
byte[] msbFirst = new byte[] { 0x42, 0xF6, 0xE9, 0xE0 };
byte[] lsbFirst = new byte[] { 0xE0, 0xE9, 0xF6, 0x42 };
const float f = 123.456789F;
byte[] b = netduino.BitConverter.GetBytes(f, netduino.BitConverter.ByteOrder.BigEndian);
for (int i = 0; i < b.Length; i++)
{
Debug.Assert(msbFirst[i] == b[i], "BitConverter.GetBytes(float, BigEndian) i=" + i);
}
Debug.Assert(f == netduino.BitConverter.ToSingle(msbFirst, 0, netduino.BitConverter.ByteOrder.BigEndian));
Console.WriteLine("All tests passed");
Console.ReadKey();
}
}
}
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