Talk:Technical Reference:State Definition - Revision history

Cstocks: Pseudocode

2010-01-05T23:07:05Z

Pseudocode

← Older revision		Revision as of 23:07, 5 January 2010
Line 67:		Line 67:

	[[User:Mellinger\|Mellinger]] 15:00, 5 January 2010 (UTC)		[[User:Mellinger\|Mellinger]] 15:00, 5 January 2010 (UTC)

			== Pseudocode ==

			Thanks for pointing that out, but to someone (like me) who is not terribly familiar with C++ code, seeing the actual code is not very helpful. For example, I would have to start hunting through the code to find out what State::ValueType, mByteLength, mpData, et cetera mean.

			Also, I am proud to note that my algorithm is at least 8 times more efficient than the C++ function you pointed me to.

Mellinger: /* Actual C++ code */

2010-01-05T15:00:21Z

Actual C++ code

← Older revision		Revision as of 15:00, 5 January 2010
Line 65:		Line 65:
	http://www.bci2000.org/tracproj/browser/trunk/src/shared/types/StateVectorSample.cpp#L69		http://www.bci2000.org/tracproj/browser/trunk/src/shared/types/StateVectorSample.cpp#L69
	(log into trac if you get a message about browser view privileges)		(log into trac if you get a message about browser view privileges)

			[[User:Mellinger\|Mellinger]] 15:00, 5 January 2010 (UTC)

Mellinger: Actual C++ code

2010-01-05T14:56:55Z

Actual C++ code

← Older revision		Revision as of 14:56, 5 January 2010
Line 59:		Line 59:

	[[User:Cstocks\|Cstocks]] 21:15, 4 January 2010 (UTC)		[[User:Cstocks\|Cstocks]] 21:15, 4 January 2010 (UTC)

			== Actual C++ code ==

			The actual C++ code is here:
			http://www.bci2000.org/tracproj/browser/trunk/src/shared/types/StateVectorSample.cpp#L69
			(log into trac if you get a message about browser view privileges)

Cstocks: Pseudocode reference

2010-01-04T21:15:23Z

Pseudocode reference

← Older revision		Revision as of 21:15, 4 January 2010
Line 38:		Line 38:

	Thanks for pointing out the error. State vector encoding is actually little-endian (LSB first) rather than big-endian, and its layout on a little-endian machine is straightforward as a concatenation of little-endian encoded state values. I fixed the description accordingly.		Thanks for pointing out the error. State vector encoding is actually little-endian (LSB first) rather than big-endian, and its layout on a little-endian machine is straightforward as a concatenation of little-endian encoded state values. I fixed the description accordingly.

			== Pseudocode reference ==

			Do you think it would be helpful to readers to put (in pseudocode) a way to read the State Definition?

			int ExtractStateValue(unsigned char[] vector, int byteoffset, int bitoffset, int numberofbits){

			int numberofbytes = numberofbits / 8 + 1;
			char bytes[numbytes] = vector[ byteoffset : byteoffset + numbytes ];

			int ret = bytes[0] >> bitoffset;
			for ( int i=1; i<numbytes; i++ ){
			ret += bytes[i] << ( 8 * i - bitoffset );
			}

			return ret % ( 1 << numbits );
			}

			This is not compilable C or C++ code, as far as I know. However, I think it might make things clearer.

			[[User:Cstocks\|Cstocks]] 21:15, 4 January 2010 (UTC)

Mellinger: Fixed section on state vector encoding

2010-01-04T12:19:31Z

Fixed section on state vector encoding

← Older revision		Revision as of 12:19, 4 January 2010
Line 34:		Line 34:
	!6!!5!!4!!3!!2!!1!!0!!0!!14!!13!!12!!11!!10!!9!!8!!7!!colspan="7"\| !!15		!6!!5!!4!!3!!2!!1!!0!!0!!14!!13!!12!!11!!10!!9!!8!!7!!colspan="7"\| !!15
	\|}		\|}

			== Fixed section on state vector encoding ==

			Thanks for pointing out the error. State vector encoding is actually little-endian (LSB first) rather than big-endian, and its layout on a little-endian machine is straightforward as a concatenation of little-endian encoded state values. I fixed the description accordingly.

Cstocks: /* State Vector */ Finally correct, again. I made a mistake before.

2010-01-01T00:45:11Z

State Vector: Finally correct, again. I made a mistake before.

← Older revision		Revision as of 00:45, 1 January 2010
Line 30:		Line 30:
	!7!!6!!5!!4!!3!!2!!1!!0		!7!!6!!5!!4!!3!!2!!1!!0
	\|-		\|-
	!colspan="7"\|SourceTime!!Running!!colspan="9"\|SourceTime!!colspan="7"\|unused		!colspan="7"\|SourceTime!!Running!!colspan="8"\|SourceTime!!colspan="7"\|unused!!SourceTime
	\|-		\|-
	!6!!5!!4!!3!!2!!1!!0!!0!!14!!13!!12!!11!!10!!9!!8!!7!~~!15~~		!6!!5!!4!!3!!2!!1!!0!!0!!14!!13!!12!!11!!10!!9!!8!!7!!colspan="7"\| !!15
	!colspan="7"\|
	\|}		\|}

Cstocks: /* State Vector */ Finally got it correct

2010-01-01T00:30:40Z

State Vector: Finally got it correct

← Older revision		Revision as of 00:30, 1 January 2010
Line 21:		Line 21:
	Which on the physical machine actually maps to:		Which on the physical machine actually maps to:

	~~(I need to correct this later)~~		{\|border="1" cellspacing="0" cellpadding="1"
			!colspan="8"\|State Vector Byte 1
			!colspan="8"\|State Vector Byte 2
			!colspan="8"\|State Vector Byte 3
			\|-
			!7!!6!!5!!4!!3!!2!!1!!0
			!7!!6!!5!!4!!3!!2!!1!!0
			!7!!6!!5!!4!!3!!2!!1!!0
			\|-
			!colspan="7"\|SourceTime!!Running!!colspan="9"\|SourceTime!!colspan="7"\|unused
			\|-
			!6!!5!!4!!3!!2!!1!!0!!0!!14!!13!!12!!11!!10!!9!!8!!7!!15
			!colspan="7"\|
			\|}

Cstocks: /* State Vector */

2010-01-01T00:24:31Z

State Vector

← Older revision		Revision as of 00:24, 1 January 2010
Line 21:		Line 21:
	Which on the physical machine actually maps to:		Which on the physical machine actually maps to:

	~~{\|border="1" cellspacing="0" cellpadding="1"~~		(I need to correct this later)
	~~!colspan="8"\|State Vector Byte 1~~
	~~!colspan="8"\|State Vector Byte 2~~
	~~!colspan="8"\|State Vector Byte 3~~
	\|-
	~~!7!!6!!5!!4!!3!!2!!1!!0~~
	~~!7!!6!!5!!4!!3!!2!!1!!0~~
	~~!7!!6!!5!!4!!3!!2!!1!!0~~
	\|-
	~~!Running!!colspan="16"\|SourceTime!!colspan="7"\|unused~~
	\|-
	!0
	~~!6!!5!!4!!3!!2!!1!!0!!14!!13!!12!!11!!10!!9!!8!!7!!15~~
	~~!colspan="7"\| ~~
	\|}

Cstocks: /* State Vector */

2010-01-01T00:23:33Z

State Vector

← Older revision		Revision as of 00:23, 1 January 2010
Line 33:		Line 33:
	\|-		\|-
	!0		!0
	!6!!5!!4!!3!!2!!1!!0~~!!15~~!!14!!13!!12!!11!!10!!9!!8!!7		!6!!5!!4!!3!!2!!1!!0!!14!!13!!12!!11!!10!!9!!8!!7!!15
	!colspan="7"\|		!colspan="7"\|
	\|}		\|}

Cstocks: State Vector

2010-01-01T00:22:27Z

State Vector

New page

== State Vector ==

The section on state vectors is totally wrong. After reverse-engineering some data files with the help of the BCI2000Viewer, it appears that the state vectors are actually encoded in reverse-big-endian. In other words, if smaller numbers represent lower order bits, then the state vector layout mentioned in this section would actually be encoded as follows:

{|border="1" cellspacing="0" cellpadding="1"
!colspan="8"|State Vector Byte 1
!colspan="8"|State Vector Byte 2
!colspan="8"|State Vector Byte 3
|-
!0!!1!!2!!3!!4!!5!!6!!7
!0!!1!!2!!3!!4!!5!!6!!7
!0!!1!!2!!3!!4!!5!!6!!7
|-
!Running!!colspan="16"|SourceTime!!colspan="7"|unused
|-
!0
!0!!1!!2!!3!!4!!5!!6!!7!!8!!9!!10!!11!!12!!13!!14!!15
!colspan="7"| 
|}

Which on the physical machine actually maps to:

{|border="1" cellspacing="0" cellpadding="1"
!colspan="8"|State Vector Byte 1
!colspan="8"|State Vector Byte 2
!colspan="8"|State Vector Byte 3
|-
!7!!6!!5!!4!!3!!2!!1!!0
!7!!6!!5!!4!!3!!2!!1!!0
!7!!6!!5!!4!!3!!2!!1!!0
|-
!Running!!colspan="16"|SourceTime!!colspan="7"|unused
|-
!0
!6!!5!!4!!3!!2!!1!!0!!15!!14!!13!!12!!11!!10!!9!!8!!7
!colspan="7"| 
|}