digitalmars.D - byte + single-bit-operations

Alexander Panek (9/9) Mar 15 2005 hello,

=?ISO-8859-15?Q?Anders_F_Bj=F6rklund?= (5/9) Mar 15 2005 Use the bit[] type. Just be aware that it always aligns the memory used

Alexander Panek (18/27) Mar 15 2005 Well, I use a bit-array. But it seems like the compiler does not want me...

=?ISO-8859-15?Q?Anders_F_Bj=F6rklund?= (17/29) Mar 15 2005 Please pick either of bit-arrays or bit-shifting, but not both at once?

=?ISO-8859-15?Q?Anders_F_Bj=F6rklund?= (7/11) Mar 15 2005 Darnit. Seems to be typo-day today. :-(
Alexander Panek (29/56) Mar 15 2005 I have to use both, because I get a byte-array ( byte[] ) and I don`t kn...

=?ISO-8859-15?Q?Anders_F_Bj=F6rklund?= (7/12) Mar 15 2005 Assuming the other logic is OK, this line should be:

Regan Heath (58/87) Mar 15 2005 You might find this helpful.

Alexander Panek (5/18) Mar 15 2005 You`re my hero! Saved my day! :)

Regan Heath (14/35) Mar 15 2005 After reading your other post, about "getting the first 7 bits" from eac...

Regan Heath (5/40) Mar 15 2005 To be honest though I haven't tried the code above. bit[] is a strange

Alexander Panek (11/61) Mar 15 2005 .. it *should* copy the first 7 bits of a byte into the bit-array, but i...

Alexander Panek (38/119) Mar 15 2005 Rearranged my code:

Regan Heath (51/175) Mar 16 2005 Odd. What happes if you change "return sms[];" to "return sms;" ?

Alexander Panek (63/112) Mar 16 2005 It was "return sms;" before, just tried out if it helps. ;)

Derek Parnell (13/59) Mar 16 2005 I think that one difference is that with non-bit arrays, element[x] has ...

Nrgyzer (2/40) May 07 2010 I tried a bit... I can't get it to work with bud... only dmd will compil...

"Alexander Panek" <alexander.panek brainsware.org> writes:

hello,

just wondered if there`s a common way to edit single bits in a byte? in C  
and C++ there were only crappy 'workarounds', but as D has a single-bit  
datatype it would be great to have an operator to read/write single bits  
in a byte-variable.

thanks for help,
alex

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Mar 15 2005

=?ISO-8859-15?Q?Anders_F_Bj=F6rklund?= <afb algonet.se> writes:

Alexander Panek wrote:

 just wondered if there`s a common way to edit single bits in a byte? in 
 C  and C++ there were only crappy 'workarounds', but as D has a 
 single-bit  datatype it would be great to have an operator to read/write 
 single bits  in a byte-variable.

Use the bit[] type. Just be aware that it always aligns the memory used
to even powers of 32 bits (4 bytes), if unioned with for instance byte.

See http://www.prowiki.org/wiki4d/wiki.cgi?BitsAndBools

--anders

Mar 15 2005

"Alexander Panek" <alexander.panek brainsware.org> writes:

On Tue, 15 Mar 2005 21:23:23 +0100, Anders F Bj�rklund <afb algonet.se>  
wrote:

 Alexander Panek wrote:

 just wondered if there`s a common way to edit single bits in a byte? in  
 C  and C++ there were only crappy 'workarounds', but as D has a  
 single-bit  datatype it would be great to have an operator to  
 read/write single bits  in a byte-variable.

 Use the bit[] type. Just be aware that it always aligns the memory used
 to even powers of 32 bits (4 bytes), if unioned with for instance byte.

 See http://www.prowiki.org/wiki4d/wiki.cgi?BitsAndBools

 --anders

Well, I use a bit-array. But it seems like the compiler does not want me  
to do this :o !

I use this code to copy a bit out of a byte into a bit-variable:

[code]
while(offset_ascii < 8) {
	result[offset_sms] = (b & (true << offset_ascii++)) << offset_sms++; //  
line 18
}
[/code]

DMD gives me this error:
" smscode.d(18): cannot implicitly convert expression (cast(int)(b) & 1 <<  
offset_ascii++) of type int to bit "

Thanks,
an hopefully Alex ;)

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Mar 15 2005

=?ISO-8859-15?Q?Anders_F_Bj=F6rklund?= <afb algonet.se> writes:

Alexander Panek wrote:

 I use this code to copy a bit out of a byte into a bit-variable:
 
 [code]
 while(offset_ascii < 8) {
     result[offset_sms] = (b & (true << offset_ascii++)) << offset_sms++; 
 //  line 18
 }
 [/code]
 
 DMD gives me this error:
 " smscode.d(18): cannot implicitly convert expression (cast(int)(b) & 1 
 <<  offset_ascii++) of type int to bit "

Please pick either of bit-arrays or bit-shifting, but not both at once?

That is, either:

bit b; // value
int bitno; // index
bit[] array;

array[bitno] = b;

Or, alternatively:

bit b; // value
int bitno;  // index
byte[] array;

if (b)
   array[bitno >> 3] &= ~(1 << (bitno & 7); // set bit
else
   array[bitno >> 3] |= 1 << (bitno & 7); // clear bit

HTH,
--anders

Mar 15 2005

=?ISO-8859-15?Q?Anders_F_Bj=F6rklund?= <afb algonet.se> writes:

Anders F Bj�rklund wrote:

 if (b)
   array[bitno >> 3] &= ~(1 << (bitno & 7); // set bit
 else
   array[bitno >> 3] |= 1 << (bitno & 7); // clear bit

Darnit. Seems to be typo-day today. :-(

   if (b)
     array[bitno >> 3] |= 1 << (bitno & 7); // set bit
   else
     array[bitno >> 3] &= ~(1 << (bitno & 7); // clear bit

--anders

Mar 15 2005

"Alexander Panek" <alexander.panek brainsware.org> writes:

On Tue, 15 Mar 2005 22:14:34 +0100, Anders F Bj�rklund <afb algonet.se>  
wrote:

 Alexander Panek wrote:

 I use this code to copy a bit out of a byte into a bit-variable:
  [code]
 while(offset_ascii < 8) {
     result[offset_sms] = (b & (true << offset_ascii++)) <<  
 offset_sms++; //  line 18
 }
 [/code]
  DMD gives me this error:
 " smscode.d(18): cannot implicitly convert expression (cast(int)(b) & 1  
 <<  offset_ascii++) of type int to bit "

 Please pick either of bit-arrays or bit-shifting, but not both at once?

 That is, either:

 bit b; // value
 int bitno; // index
 bit[] array;

 array[bitno] = b;

 Or, alternatively:

 bit b; // value
 int bitno;  // index
 byte[] array;

 if (b)
    array[bitno >> 3] &= ~(1 << (bitno & 7); // set bit
 else
    array[bitno >> 3] |= 1 << (bitno & 7); // clear bit

 HTH,
 --anders

I have to use both, because I get a byte-array ( byte[] ) and I don`t know  
any other way to get the first 7 bits out of every byte.

That`s the whole function:


bit [] toSMSCode(byte[] ascii)
{
	bit [] result;
	int offset_sms, offset_ascii;
	
	offset_sms = 0;
	offset_ascii = 0;
	
	foreach(byte b; ascii)
	{
		while(offset_ascii < 8)
		{
			result[offset_sms] = (b & (true << offset_ascii++)) << offset_sms++;
		}
		offset_ascii = 0;
	}
	
	return result;
}

It (should) converts ASCII-strings to SMS-coded-strings (only 7bits of 8  
used, so the string gets smaller).

Thanks for giving trouble, Alex

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Mar 15 2005

=?ISO-8859-15?Q?Anders_F_Bj=F6rklund?= <afb algonet.se> writes:

Alexander Panek wrote:

 I have to use both, because I get a byte-array ( byte[] ) and I don`t 
 know  any other way to get the first 7 bits out of every byte.

OK, thanks for clearifying...

 That`s the whole function:

             result[offset_sms] = (b & (true << offset_ascii++)) << 
 offset_sms++;

Assuming the other logic is OK, this line should be:

   result[offset_sms++] = (b & (1 << offset_ascii++)) != 0;

I think that you can take it from here, if it's not...
(for instance, you need to set a result.length first)

--anders

Mar 15 2005

"Regan Heath" <regan netwin.co.nz> writes:

On Tue, 15 Mar 2005 22:05:36 +0100, Alexander Panek  
<alexander.panek brainsware.org> wrote:
 On Tue, 15 Mar 2005 21:23:23 +0100, Anders F Bj�rklund <afb algonet.se>  
 wrote:

 Alexander Panek wrote:

 just wondered if there`s a common way to edit single bits in a byte?  
 in C  and C++ there were only crappy 'workarounds', but as D has a  
 single-bit  datatype it would be great to have an operator to  
 read/write single bits  in a byte-variable.

 Use the bit[] type. Just be aware that it always aligns the memory used
 to even powers of 32 bits (4 bytes), if unioned with for instance byte.

 See http://www.prowiki.org/wiki4d/wiki.cgi?BitsAndBools

 --anders

 Well, I use a bit-array. But it seems like the compiler does not want me  
 to do this :o !

 I use this code to copy a bit out of a byte into a bit-variable:

 [code]
 while(offset_ascii < 8) {
 	result[offset_sms] = (b & (true << offset_ascii++)) << offset_sms++; //  
 line 18
 }
 [/code]

 DMD gives me this error:
 " smscode.d(18): cannot implicitly convert expression (cast(int)(b) & 1  
 << offset_ascii++) of type int to bit "

 Thanks,
 an hopefully Alex ;)

You might find this helpful.

















































Basically you can create a bit[] by slicing any location in memory, you  
just have to know it's starting location and how big the memory is, in  
bits.

Something I don't understand is happening with the 'long', can someone  
explain this to me please. :)

Re-writing your code, assuming 'result' is a bit[] and 'b' is a byte:
   result = (cast(bit*)b)[0..8];

Regan

Mar 15 2005

"Alexander Panek" <alexander.panek brainsware.org> writes:

On Wed, 16 Mar 2005 10:17:11 +1300, Regan Heath <regan netwin.co.nz> wrote:






 Basically you can create a bit[] by slicing any location in memory, you  
 just have to know it's starting location and how big the memory is, in  
 bits.

 Something I don't understand is happening with the 'long', can someone  
 explain this to me please. :)

 Re-writing your code, assuming 'result' is a bit[] and 'b' is a byte:
    result = (cast(bit*)b)[0..8];

 Regan

You`re my hero! Saved my day! :)

Thank you very much, Alex

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Mar 15 2005

"Regan Heath" <regan netwin.co.nz> writes:

On Tue, 15 Mar 2005 22:27:44 +0100, Alexander Panek  
<alexander.panek brainsware.org> wrote:
 On Wed, 16 Mar 2005 10:17:11 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:






 Basically you can create a bit[] by slicing any location in memory, you  
 just have to know it's starting location and how big the memory is, in  
 bits.

 Something I don't understand is happening with the 'long', can someone  
 explain this to me please. :)

 Re-writing your code, assuming 'result' is a bit[] and 'b' is a byte:
    result = (cast(bit*)b)[0..8];

 Regan

 You`re my hero! Saved my day! :)
 Thank you very much, Alex

After reading your other post, about "getting the first 7 bits" from each  
byte (I've written some sms decode/encode routines in C BTW) you could do  
something like...

bit[] result;
bit[] part;

foreach(byte b; raw_data) {
	part = (cast(bit*)byte)[0..7];
	result ~= part;
}

or similar to grab 7 bits from each byte (whether it's the correct 7 bits  
or not I haven't thought about, I'll leave that to you).

Regan

Mar 15 2005

"Regan Heath" <regan netwin.co.nz> writes:

On Wed, 16 Mar 2005 10:59:21 +1300, Regan Heath <regan netwin.co.nz> wrote:
 On Tue, 15 Mar 2005 22:27:44 +0100, Alexander Panek  
 <alexander.panek brainsware.org> wrote:
 On Wed, 16 Mar 2005 10:17:11 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:






 Basically you can create a bit[] by slicing any location in memory,  
 you just have to know it's starting location and how big the memory  
 is, in bits.

 Something I don't understand is happening with the 'long', can someone  
 explain this to me please. :)

 Re-writing your code, assuming 'result' is a bit[] and 'b' is a byte:
    result = (cast(bit*)b)[0..8];

 Regan

 You`re my hero! Saved my day! :)
 Thank you very much, Alex

 After reading your other post, about "getting the first 7 bits" from  
 each byte (I've written some sms decode/encode routines in C BTW) you  
 could do something like...

 bit[] result;
 bit[] part;

 foreach(byte b; raw_data) {
 	part = (cast(bit*)byte)[0..7];
 	result ~= part;
 }

 or similar to grab 7 bits from each byte (whether it's the correct 7  
 bits or not I haven't thought about, I'll leave that to you).

To be honest though I haven't tried the code above. bit[] is a strange  
beast, not like other array types in some situations... one would hope the  
above code works though it may not.

Regan

Mar 15 2005

"Alexander Panek" <alexander.panek brainsware.org> writes:

On Wed, 16 Mar 2005 11:02:53 +1300, Regan Heath <regan netwin.co.nz> wrote:

 On Wed, 16 Mar 2005 10:59:21 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:
 On Tue, 15 Mar 2005 22:27:44 +0100, Alexander Panek  
 <alexander.panek brainsware.org> wrote:
 On Wed, 16 Mar 2005 10:17:11 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:






 Basically you can create a bit[] by slicing any location in memory,  
 you just have to know it's starting location and how big the memory  
 is, in bits.

 Something I don't understand is happening with the 'long', can  
 someone explain this to me please. :)

 Re-writing your code, assuming 'result' is a bit[] and 'b' is a byte:
    result = (cast(bit*)b)[0..8];

 Regan

 You`re my hero! Saved my day! :)
 Thank you very much, Alex

 After reading your other post, about "getting the first 7 bits" from  
 each byte (I've written some sms decode/encode routines in C BTW) you  
 could do something like...

 bit[] result;
 bit[] part;

 foreach(byte b; raw_data) {
 	part = (cast(bit*)byte)[0..7];
 	result ~= part;
 }

 or similar to grab 7 bits from each byte (whether it's the correct 7  
 bits or not I haven't thought about, I'll leave that to you).

 To be honest though I haven't tried the code above. bit[] is a strange  
 beast, not like other array types in some situations... one would hope  
 the above code works though it may not.

 Regan

My code is quite similar to yours:

 	foreach(byte b; ascii)
 	{
 		sms[offset_sms..(offset_sms + 6)] = (cast(bit*)&b)[0..6];
 		offset_sms += 7;
 	}

.. it *should* copy the first 7 bits of a byte into the bit-array, but it  
allways ends up either with an ArrayBoundsError, or something like that:  
"Error: lengths don't match for array copy".
I already tried to modify the length of "bit [] sms" dynamically, so it`s  
allways big enough to get the next 7 bits -> same errors. (Well, the first  
2 steps of the loop are working, but then it gives the ArrayBoundsError.)

Alex

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Mar 15 2005

"Alexander Panek" <alexander.panek brainsware.org> writes:

On Wed, 16 Mar 2005 07:16:00 +0100, Alexander Panek  
<alexander.panek brainsware.org> wrote:

 On Wed, 16 Mar 2005 11:02:53 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:

 On Wed, 16 Mar 2005 10:59:21 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:
 On Tue, 15 Mar 2005 22:27:44 +0100, Alexander Panek  
 <alexander.panek brainsware.org> wrote:
 On Wed, 16 Mar 2005 10:17:11 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:






 Basically you can create a bit[] by slicing any location in memory,  
 you just have to know it's starting location and how big the memory  
 is, in bits.

 Something I don't understand is happening with the 'long', can  
 someone explain this to me please. :)

 Re-writing your code, assuming 'result' is a bit[] and 'b' is a byte:
    result = (cast(bit*)b)[0..8];

 Regan

 You`re my hero! Saved my day! :)
 Thank you very much, Alex

 After reading your other post, about "getting the first 7 bits" from  
 each byte (I've written some sms decode/encode routines in C BTW) you  
 could do something like...

 bit[] result;
 bit[] part;

 foreach(byte b; raw_data) {
 	part = (cast(bit*)byte)[0..7];
 	result ~= part;
 }

 or similar to grab 7 bits from each byte (whether it's the correct 7  
 bits or not I haven't thought about, I'll leave that to you).

 To be honest though I haven't tried the code above. bit[] is a strange  
 beast, not like other array types in some situations... one would hope  
 the above code works though it may not.

 Regan

 My code is quite similar to yours:

 	foreach(byte b; ascii)
 	{
 		sms[offset_sms..(offset_sms + 6)] = (cast(bit*)&b)[0..6];
 		offset_sms += 7;
 	}

 .. it *should* copy the first 7 bits of a byte into the bit-array, but  
 it allways ends up either with an ArrayBoundsError, or something like  
 that: "Error: lengths don't match for array copy".
 I already tried to modify the length of "bit [] sms" dynamically, so  
 it`s allways big enough to get the next 7 bits -> same errors. (Well,  
 the first 2 steps of the loop are working, but then it gives the  
 ArrayBoundsError.)

 Alex

Rearranged my code:

 bit [] enSMS(byte [] ascii)
 {
 	bit [] sms;
 	uint i = 1;
 	//sms.length = (ascii.length * 7);

 	foreach(byte b; ascii)
 	{
 		writefln("encoding .. byte:", i);
 		if(i == ascii.length) {
 			writefln("last byte!");
 			return sms[];
 		}
 		sms ~= (cast(bit*)&b)[0..6];
 		i++;
 	}
 	
 	return sms[];
 }

Works fine .. until the loop is finished, or the return is made - I don`t  
know.

Output:

Y:\Programming\D\SMS Codierung>smscode
encoding .. byte:1
encoding .. byte:2
encoding .. byte:3
encoding .. byte:4
encoding .. byte:5
encoding .. byte:6
encoding .. byte:7
encoding .. byte:8
encoding .. byte:9
encoding .. byte:10
encoding .. byte:11
encoding .. byte:12
encoding .. byte:13
encoding .. byte:14
encoding .. byte:15
encoding .. byte:16
encoding .. byte:17
encoding .. byte:18
encoding .. byte:19
encoding .. byte:20
encoding .. byte:21
encoding .. byte:22
encoding .. byte:23
encoding .. byte:24
encoding .. byte:25
last byte!
Error: lengths don't match for array copy


..well, I`m helpless :) .

Thanks, Alex



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Mar 15 2005

"Regan Heath" <regan netwin.co.nz> writes:

On Wed, 16 Mar 2005 07:33:18 +0100, Alexander Panek  
<alexander.panek brainsware.org> wrote:
 On Wed, 16 Mar 2005 07:16:00 +0100, Alexander Panek  
 <alexander.panek brainsware.org> wrote:

 On Wed, 16 Mar 2005 11:02:53 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:

 On Wed, 16 Mar 2005 10:59:21 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:
 On Tue, 15 Mar 2005 22:27:44 +0100, Alexander Panek  
 <alexander.panek brainsware.org> wrote:
 On Wed, 16 Mar 2005 10:17:11 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:






 Basically you can create a bit[] by slicing any location in memory,  
 you just have to know it's starting location and how big the memory  
 is, in bits.

 Something I don't understand is happening with the 'long', can  
 someone explain this to me please. :)

 Re-writing your code, assuming 'result' is a bit[] and 'b' is a  
 byte:
    result = (cast(bit*)b)[0..8];

 Regan

 You`re my hero! Saved my day! :)
 Thank you very much, Alex

 After reading your other post, about "getting the first 7 bits" from  
 each byte (I've written some sms decode/encode routines in C BTW) you  
 could do something like...

 bit[] result;
 bit[] part;

 foreach(byte b; raw_data) {
 	part = (cast(bit*)byte)[0..7];
 	result ~= part;
 }

 or similar to grab 7 bits from each byte (whether it's the correct 7  
 bits or not I haven't thought about, I'll leave that to you).

 To be honest though I haven't tried the code above. bit[] is a strange  
 beast, not like other array types in some situations... one would hope  
 the above code works though it may not.

 Regan

 My code is quite similar to yours:

 	foreach(byte b; ascii)
 	{
 		sms[offset_sms..(offset_sms + 6)] = (cast(bit*)&b)[0..6];
 		offset_sms += 7;
 	}

 .. it *should* copy the first 7 bits of a byte into the bit-array, but  
 it allways ends up either with an ArrayBoundsError, or something like  
 that: "Error: lengths don't match for array copy".
 I already tried to modify the length of "bit [] sms" dynamically, so  
 it`s allways big enough to get the next 7 bits -> same errors. (Well,  
 the first 2 steps of the loop are working, but then it gives the  
 ArrayBoundsError.)

 Alex

 Rearranged my code:

 bit [] enSMS(byte [] ascii)
 {
 	bit [] sms;
 	uint i = 1;
 	//sms.length = (ascii.length * 7);

 	foreach(byte b; ascii)
 	{
 		writefln("encoding .. byte:", i);
 		if(i == ascii.length) {
 			writefln("last byte!");
 			return sms[];
 		}
 		sms ~= (cast(bit*)&b)[0..6];
 		i++;
 	}
 	
 	return sms[];
 }

 Works fine .. until the loop is finished, or the return is made - I  
 don`t know.

 Output:

 Y:\Programming\D\SMS Codierung>smscode
 encoding .. byte:1
 encoding .. byte:2
 encoding .. byte:3
 encoding .. byte:4
 encoding .. byte:5
 encoding .. byte:6
 encoding .. byte:7
 encoding .. byte:8
 encoding .. byte:9
 encoding .. byte:10
 encoding .. byte:11
 encoding .. byte:12
 encoding .. byte:13
 encoding . byte:14
 encoding .. byte:15
 encoding .. byte:16
 encoding .. byte:17
 encoding .. byte:18
 encoding .. byte:19
 encoding .. byte:20
 encoding .. byte:21
 encoding .. byte:22
 encoding .. byte:23
 encoding .. byte:24
 encoding .. byte:25
 last byte!
 Error: lengths don't match for array copy


 ..well, I`m helpless :) .

Odd. What happes if you change "return sms[];" to "return sms;" ?

I am having different trouble, no array bounds errors for me, but...

import std.stdio;

void main()
{
	byte[] ascii = cast(byte[])"0000";
	bit[] sms;
	bit[] tmp;
	
	writef("ASC:");
	foreach(int i, bit bb; (cast(bit*)ascii.ptr)[0..32]) {
		if (i && i%8 == 0) writef(" ");
		writef("%d",bb);
	}
	writefln("");
	
	foreach(int j, byte b; ascii) {
		tmp = (cast(bit*)&b)[0..7];		
		
		writef("TMP:");
		for(int k = 0; k < j; k++) writef("         ");
		foreach(int i, bit b; tmp) writef("%d",b);
		writefln("");
		
		sms ~= tmp;
		
		writef("SMS:");
		foreach(int i, bit b; sms) {
			if (i && i%7 == 0) writef("  ");
			writef("%d",b);
		}
		writefln("");
	}
	writefln("");
}

output:

ASC:00001100 00001100 00001100 00001100
TMP:0000110
SMS:0000110
TMP:         0000110
SMS:0000110  0010111
TMP:                  0000110
SMS:0000110  0010111  0010000
TMP:                           0000110
SMS:0000110  0010111  0010000  0100000

'tmp' is appended to 'sms' each time round the loop, but something is  
going very wrong.

Anyone got any ideas?

Regan

Mar 16 2005

"Alexander Panek" <alexander.panek brainsware.org> writes:

On Wed, 16 Mar 2005 22:10:30 +1300, Regan Heath <regan netwin.co.nz> wrote:

 Odd. What happes if you change "return sms[];" to "return sms;" ?

 I am having different trouble, no array bounds errors for me, but...

 import std.stdio;

 void main()
 {
 	byte[] ascii = cast(byte[])"0000";
 	bit[] sms;
 	bit[] tmp;
 	
 	writef("ASC:");
 	foreach(int i, bit bb; (cast(bit*)ascii.ptr)[0..32]) {
 		if (i && i%8 == 0) writef(" ");
 		writef("%d",bb);
 	}
 	writefln("");
 	
 	foreach(int j, byte b; ascii) {
 		tmp = (cast(bit*)&b)[0..7];		
 		
 		writef("TMP:");
 		for(int k = 0; k < j; k++) writef("         ");
 		foreach(int i, bit b; tmp) writef("%d",b);
 		writefln("");
 		
 		sms ~= tmp;
 		
 		writef("SMS:");
 		foreach(int i, bit b; sms) {
 			if (i && i%7 == 0) writef("  ");
 			writef("%d",b);
 		}
 		writefln("");
 	}
 	writefln("");
 }

 output:

 ASC:00001100 00001100 00001100 00001100
 TMP:0000110
 SMS:0000110
 TMP:         0000110
 SMS:0000110  0010111
 TMP:                  0000110
 SMS:0000110  0010111  0010000
 TMP:                           0000110
 SMS:0000110  0010111  0010000  0100000

 'tmp' is appended to 'sms' each time round the loop, but something is  
 going very wrong.

 Anyone got any ideas?

 Regan

It was "return sms;" before, just tried out if it helps. ;)

For some reason the encoded string seems to be bigger than the  
ascii-string here:

string has 6bytes
encoding .. byte:1
0000110\
  0000110
encoding .. byte:2
1000110\
  00001100 000000
encoding .. byte:3
0000110\
  00001100 00000000 00000
encoding .. byte:4
1000110\
  00001100 00000000 00000000 0000
encoding .. byte:5
0000110\
  00001100 00000000 00000000 00000000 001
encoding .. byte:6 (last byte!)
1000110\
  00001100 00000000 00000000 00000000 00111111 01Error: lengths don't match  
for array copy
  <--------------------------------------------->
                  = 5bytes + 2 bits

current code:

//  
=========================================================================
bit [] enSMS(byte [] ascii)
{
	bit [] sms, tmp;
	uint i = 1;
	//sms.length = (ascii.length * 7);
	
	writef("string(", cast(char[])ascii, ") has ", ascii.length, "bytes");

	foreach(byte by; ascii)
	{
		writef("\nencoding .. byte:", i);
		if(i == ascii.length)
			writefln(" (last byte!)");
		else
			writefln("");

		tmp = (cast(bit*)&by)[0..7];

		foreach(bit b; tmp) {
			writef("%d",b);
		}

		sms ~= tmp;

		foreach(int j, bit b; sms) {
			if(j%50 == 0) writefln("\\");
			if(j%8 == 0)writef(" ");
			writef("%d",b);
		}
		i++;
	}

	return sms;
}
//  
=========================================================================

So, as you see, I`ve got the same problem.

Alex
-- 
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

Mar 16 2005

Derek Parnell <derek psych.ward> writes:

On Wed, 16 Mar 2005 11:02:53 +1300, Regan Heath wrote:

 On Wed, 16 Mar 2005 10:59:21 +1300, Regan Heath <regan netwin.co.nz> wrote:
 On Tue, 15 Mar 2005 22:27:44 +0100, Alexander Panek  
 <alexander.panek brainsware.org> wrote:
 On Wed, 16 Mar 2005 10:17:11 +1300, Regan Heath <regan netwin.co.nz>  
 wrote:






 Basically you can create a bit[] by slicing any location in memory,  
 you just have to know it's starting location and how big the memory  
 is, in bits.

 Something I don't understand is happening with the 'long', can someone  
 explain this to me please. :)

 Re-writing your code, assuming 'result' is a bit[] and 'b' is a byte:
    result = (cast(bit*)b)[0..8];

 Regan

 You`re my hero! Saved my day! :)
 Thank you very much, Alex

 After reading your other post, about "getting the first 7 bits" from  
 each byte (I've written some sms decode/encode routines in C BTW) you  
 could do something like...

 bit[] result;
 bit[] part;

 foreach(byte b; raw_data) {
 	part = (cast(bit*)byte)[0..7];
 	result ~= part;
 }

 or similar to grab 7 bits from each byte (whether it's the correct 7  
 bits or not I haven't thought about, I'll leave that to you).

 
 To be honest though I haven't tried the code above. bit[] is a strange  
 beast, not like other array types in some situations... one would hope the  
 above code works though it may not.
 
 Regan

I think that one difference is that with non-bit arrays, element[x] has a
lower RAM address than element[x+1], but it is the reverse with bit arrays.
For example, if you have a bit array of 32 bits, the elements 0-7 inclusive
might have an address of 0xFE78 (for one byte), elements 8-15 inclusive
will have an address of 0xFE77, elements 16-23 will have the address
0xFE76, and the last octet will have the address 0xFE75. Such that if you
set "element[31]=1", it means that the left-most bit at address 0xFE75 will
be set, and "element[0]=1" will set the rightmost bit at address 0xFE78.

-- 
Derek Parnell
Melbourne, Australia
16/03/2005 9:43:04 PM

Mar 16 2005

Nrgyzer <nrgyzer gmail.com> writes:

Alexander Panek Wrote:

 On Tue, 15 Mar 2005 21:23:23 +0100, Anders F Bj�rklund <afb algonet.se>  
 wrote:
 
 Alexander Panek wrote:

 just wondered if there`s a common way to edit single bits in a byte? in  
 C  and C++ there were only crappy 'workarounds', but as D has a  
 single-bit  datatype it would be great to have an operator to  
 read/write single bits  in a byte-variable.

 Use the bit[] type. Just be aware that it always aligns the memory used
 to even powers of 32 bits (4 bytes), if unioned with for instance byte.

 See http://www.prowiki.org/wiki4d/wiki.cgi?BitsAndBools

 --anders

 
 Well, I use a bit-array. But it seems like the compiler does not want me  
 to do this :o !
 
 I use this code to copy a bit out of a byte into a bit-variable:
 
 [code]
 while(offset_ascii < 8) {
 	result[offset_sms] = (b & (true << offset_ascii++)) << offset_sms++; //  
 line 18
 }
 [/code]
 
 DMD gives me this error:
 " smscode.d(18): cannot implicitly convert expression (cast(int)(b) & 1 <<  
 offset_ascii++) of type int to bit "
 
 Thanks,
 an hopefully Alex ;)
 
 -- 
 Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

I tried a bit... I can't get it to work with bud... only dmd will compile the
source. When I first compile with dmd and then with bud, it works with bud, too
- but only until I didn't use the -clean flag when I build the exe-file.

May 07 2010

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