How to Convert Binary Coded Hex Byte Array to Byte

[Charles Law]

I thought this was going to be straight forward, given the wealth of
conversion functions in .NET, but it is proving more convoluted than
imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a succinct
conversion for it]

 

[Herfried K. Wagner [MVP]]

I thought this was going to be straight forward, given the wealth of
conversion functions in .NET, but it is proving more convoluted than
imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a succinct
conversion for it]

There can be many functions...

\\\
Public Function Foo(ByVal abyt() As Byte) As Byte
Return &H40
End Function
///

SCNR

 

[Charles Law]

Hi Herfried

As I was making coffee I realised my mistake (in the post). It should read

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h34
ba(1) = &h30

b = foo(ba)
</code>

Still looking for foo() such that b contains &h40.

Charles

I thought this was going to be straight forward, given the wealth of
conversion functions in .NET, but it is proving more convoluted than
imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a succinct
conversion for it]

There can be many functions...

\\\
Public Function Foo(ByVal abyt() As Byte) As Byte
Return &H40
End Function
///

SCNR

 

[Charles Law]

Correction

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h34
ba(1) = &h30

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles

 

[Armin Zingler]

I thought this was going to be straight forward, given the wealth
of conversion functions in .NET, but it is proving more convoluted
than imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a
succinct conversion for it]

What if ba(0) or ba(1) > &Hf?

If both are [0; &HF]:

b = ba(0) << 4 or ba(1)


--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Charles Law]

Hi Armin

Sorry for the confusion, but I think my correction is a bit slow coming
through. I should have written

ba(0) = &h34
ba(1) = &h30

Charles

I thought this was going to be straight forward, given the wealth
of conversion functions in .NET, but it is proving more convoluted
than imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a
succinct conversion for it]

What if ba(0) or ba(1) > &Hf?

If both are [0; &HF]:

b = ba(0) << 4 or ba(1)


--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Herfried K. Wagner [MVP]]

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h34
ba(1) = &h30

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

There are still thousands of ways to return this result. Do you have
other (input, outpuut) pairs?

 

[Armin Zingler]

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

What if ba(0) or ba(1) > &Hf?

If both are [0; &HF]:

b = ba(0) << 4 or ba(1)

Sorry for the confusion, but I think my correction is a bit slow
coming through. I should have written

ba(0) = &h34
ba(1) = &h30

Expected result? &H3430?

Dim ba(1) As Byte
Dim s As Short

ba(0) = &H34
ba(1) = &H30

s = CShort(ba(0)) << 8 Or ba(1)


If you can exchange the byte order, this is also possible:

s = System.BitConverter.ToInt16(ba, 0)



--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Charles Law]

Thousands? I only need one ;-)

This is currently the only scenario. As a stop-gap, I have

<code>
Dim enc As New Text.ASCIIEncoding

Return CByte("&H" & enc.GetString(ba))
</code>

which I imagine you will say is as good as any, but prepending "&H" to the
string just seems a bit 'kludgy'.

Charles

 

[Charles Law]

Hi Armin

No. Expected result still &H40.

Unfortunately, I cannot easily change the byte order as these are sent to me
from an external source, as binary coded hex digits.

Charles

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

What if ba(0) or ba(1) > &Hf?

If both are [0; &HF]:

b = ba(0) << 4 or ba(1)

Sorry for the confusion, but I think my correction is a bit slow
coming through. I should have written

ba(0) = &h34
ba(1) = &h30

Expected result? &H3430?

Dim ba(1) As Byte
Dim s As Short

ba(0) = &H34
ba(1) = &H30

s = CShort(ba(0)) << 8 Or ba(1)


If you can exchange the byte order, this is also possible:

s = System.BitConverter.ToInt16(ba, 0)



--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Jay B. Harlow [MVP - Outlook]]

Charles,
Use Armin's code, only anding with &hf first.

Public Function Foo(ByVal bytes() As Byte) As Byte
Const mask As Byte = &HF
Return (bytes(0) And mask) << 4 Or (bytes(1) And mask)
End Function

Hope this helps
Jay

Hi Armin

Sorry for the confusion, but I think my correction is a bit slow coming
through. I should have written

ba(0) = &h34
ba(1) = &h30

Charles

I thought this was going to be straight forward, given the wealth
of conversion functions in .NET, but it is proving more convoluted
than imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a
succinct conversion for it]

What if ba(0) or ba(1) > &Hf?

If both are [0; &HF]:

b = ba(0) << 4 or ba(1)


--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Charles Law]

Hi Jay

Thanks. I was trying to avoid byte shifting and masking if possible. I had
hoped that there was a higher level solution, using a combination of the
Convert class and perhaps Encoding/Decoding. There seem to be so many ways
of performing conversions that I thought there must be one to translate
binary code hex. For example, what about foo() where

Dim s As String
Dim b As Byte

s = "40"

b = foo(s)

to give b equal to &H40. Clearly, I can put &H on the beginning of the
string and use CByte(), as I put in my response to Herfried, but that just
seems low-tech. After all, there is a way to create a hex string from a
byte:

Convert.ToString(&H40, 16) gives "40"

so isn't there something to do the reverse?

Charles

Charles,
Use Armin's code, only anding with &hf first.

Public Function Foo(ByVal bytes() As Byte) As Byte
Const mask As Byte = &HF
Return (bytes(0) And mask) << 4 Or (bytes(1) And mask)
End Function

Hope this helps
Jay

Hi Armin

Sorry for the confusion, but I think my correction is a bit slow coming
through. I should have written

ba(0) = &h34
ba(1) = &h30

Charles

I thought this was going to be straight forward, given the wealth
of conversion functions in .NET, but it is proving more convoluted
than imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a
succinct conversion for it]


What if ba(0) or ba(1) > &Hf?

If both are [0; &HF]:

b = ba(0) << 4 or ba(1)


--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Armin Zingler]

No. Expected result still &H40.

How do you get &H40 from &H34 and &H30 ??


Aaah.. now I understand. Both values are character codes. You should have
mentioned!

dim b as byte

b = System.Convert.ToByte(Chr(ba(0)) & Chr(ba(1)), 16)

Or, for performance reasons:

Dim c(1) As Char
c(0) = Convert.ToChar(ba(0))
c(1) = Convert.ToChar(ba(1))
b = System.Convert.ToByte(New String(c), 16)

You may also consider declaring c as static (static c(1) as char).


.....


Another (untested!) version:

Private Function foo(ByVal b As Byte()) As Byte
Static b0, b1 As Byte

Select Case b(0)
Case Is > 70
b0 = b(0) - CByte(87)
Case Is > 57
b0 = b(0) - CByte(55)
Case Else
b0 = b(0) - CByte(48)
End Select

Select Case b(1)
Case Is > 70
b1 = b(1) - CByte(87)
Case Is > 57
b1 = b(1) - CByte(55)
Case Else
b1 = b(1) - CByte(48)
End Select


Return (b0 << 4) Or b1

End Function



--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Jay B. Harlow [MVP - Outlook]]

Charles,

Thanks. I was trying to avoid byte shifting and masking if possible. I had

Only via the various methods previously mentioned (BitConverter)

Convert.ToString(&H40, 16) gives "40"
so isn't there something to do the reverse?

You mean?

Dim s As String = b.ToString("X")

Hope this helps
Jay

Hi Jay

Thanks. I was trying to avoid byte shifting and masking if possible. I had
hoped that there was a higher level solution, using a combination of the
Convert class and perhaps Encoding/Decoding. There seem to be so many ways
of performing conversions that I thought there must be one to translate
binary code hex. For example, what about foo() where

Dim s As String
Dim b As Byte

s = "40"

b = foo(s)

to give b equal to &H40. Clearly, I can put &H on the beginning of the
string and use CByte(), as I put in my response to Herfried, but that just
seems low-tech. After all, there is a way to create a hex string from a
byte:

Convert.ToString(&H40, 16) gives "40"

so isn't there something to do the reverse?

Charles

Charles,
Use Armin's code, only anding with &hf first.

Public Function Foo(ByVal bytes() As Byte) As Byte
Const mask As Byte = &HF
Return (bytes(0) And mask) << 4 Or (bytes(1) And mask)
End Function

Hope this helps
Jay

Hi Armin

Sorry for the confusion, but I think my correction is a bit slow coming
through. I should have written

ba(0) = &h34
ba(1) = &h30

Charles


I thought this was going to be straight forward, given the wealth
of conversion functions in .NET, but it is proving more convoluted
than imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a
succinct conversion for it]


What if ba(0) or ba(1) > &Hf?

If both are [0; &HF]:

b = ba(0) << 4 or ba(1)


--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Herfried K. Wagner [MVP]]

Thousands? I only need one ;-)

Sorry, for some reason, I misread the thread of the topic...

 

[Jay B. Harlow [MVP - Outlook]]

Armin,

How do you get &H40 from &H34 and &H30 ??

Aaah.. now I understand. Both values are character codes. You should have
mentioned!

Aaah! indeed...

I was thinking zoned decimal which is the AS/400 mainframe (read EBCDIC)
equivalent...

Hopefully Charles has enough ideas to find one that fits what he needs.

Jay

 

[Charles Law]

Hi Jay

I don't think I do. In my example I was trying to show a byte being
converted to its hex string representation (w/o the &H). So the reverse I
was looking for was a hex string being converted to its byte equivalent. As
I say, I can put &H on the front and use CByte(), but that is cheating
really, and not an exact reversal as it requires some tampering with the
string to achieve the effect.

Charles

Charles,

Thanks. I was trying to avoid byte shifting and masking if possible. I

had
Only via the various methods previously mentioned (BitConverter)

Convert.ToString(&H40, 16) gives "40"
so isn't there something to do the reverse?

You mean?

Dim s As String = b.ToString("X")

Hope this helps
Jay

Hi Jay

Thanks. I was trying to avoid byte shifting and masking if possible. I had
hoped that there was a higher level solution, using a combination of the
Convert class and perhaps Encoding/Decoding. There seem to be so many ways
of performing conversions that I thought there must be one to translate
binary code hex. For example, what about foo() where

Dim s As String
Dim b As Byte

s = "40"

b = foo(s)

to give b equal to &H40. Clearly, I can put &H on the beginning of the
string and use CByte(), as I put in my response to Herfried, but that just
seems low-tech. After all, there is a way to create a hex string from a
byte:

Convert.ToString(&H40, 16) gives "40"

so isn't there something to do the reverse?

Charles

Charles,
Use Armin's code, only anding with &hf first.

Public Function Foo(ByVal bytes() As Byte) As Byte
Const mask As Byte = &HF
Return (bytes(0) And mask) << 4 Or (bytes(1) And mask)
End Function

Hope this helps
Jay

Hi Armin

Sorry for the confusion, but I think my correction is a bit slow coming
through. I should have written

ba(0) = &h34
ba(1) = &h30

Charles


I thought this was going to be straight forward, given the wealth
of conversion functions in .NET, but it is proving more convoluted
than imagined.

Given the following

<code>
Dim ba(1) As Byte
Dim b As Byte

ba(0) = &h4
ba(1) = &h0

b = foo(ba)
</code>

What is foo() such that b contains &h40 ?

TIA

Charles
[I could write an algorithm for this, but there must surely be a
succinct conversion for it]


What if ba(0) or ba(1) > &Hf?

If both are [0; &HF]:

b = ba(0) << 4 or ba(1)


--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Charles Law]

Hmm. You're going to think I am hard to please, but it doesn't quite do it
for me yet.

I prefer the latter, but it involves processing each element individually,
which troubles me.

I posted the following in response to Herfried

<code>
Dim enc As New Text.ASCIIEncoding

Return CByte("&H" & enc.GetString(ba))
</code>

which is more on the lines of what I was hoping for, but I am still unhappy
with the prepending of &H. If I could find a way w/o having to do that then
I think I would say I had taken it as far as I could.

Charles

 

[Charles Law]

It's actually a programmable power supply, that returns its status as a 2
byte hex string, and "40" (bit 6 set) means that the output has been
switched off from the front panel.

I realise that probably doesn't help, but I thought you might be interested
to know ;-)

Charles

 

[Jay B. Harlow [MVP - Outlook]]

Charles,
If "bit 6" has meaning I would convert the 2 byte hex string, to an Enum.
Then define an Enum to be what the different bit positions are:

<Flags()> _
Public Enum Status
Off = &h40
End Enum

I would include FlagsAttribute if you can get more then one status at a
time, if you can only have a single status at a time, I would not include
the FlagsAttribute.

I would define the enum such that BitConverter converted the bits
correctly...

Hope this helps
Jay