Hi,
The buffer parser node doesn't allow decimal values at box length and offset box. I need to get the value in group of bits smaller than 8 bits=1byte, in this example, 3 bits representation. How can I do it?
Hi,
The buffer parser node doesn't allow decimal values at box length and offset box. I need to get the value in group of bits smaller than 8 bits=1byte, in this example, 3 bits representation. How can I do it?
Hi.
That makes no sense. If you want a value from parts of a byte, then either use the mask and scale or do it outside of the buffer parser.
E.g a mask of 0x07 will give you the value of first 3 bits.
so value 1111 1111
+ mask 0000 0111
will become 0000 0111
== 7
E.g. a mask of 0xe0 will give you the value in 3 msb bits. You then scale that by 0.03125
(to shift bits 5 places to the right)
so value 1111 1111
+ mask 1110 0000
will become (1110 0000
* 0.03125
) == 0000 0111
== 7
NOTE:
Scale 0.25
is the same as Right Shift 2 or 1 / Math.pow(2,2)
- i.e. shift right 2 bits
Scale 0.125
is the same as Right Shift 3 or 1 / Math.pow(2,3)
- i.e. shift right 3 bits
Scale 0.0625
is the same as Right Shift 4 or 1 / Math.pow(2,4)
- i.e. shift right 4 bits
Scale 0.03125
is the same as Right Shift 5 or 1 / Math.pow(2,5)
- i.e. shift right 5 bits
Scale 0.015625
is the same as Right Shift 6 or 1 / Math.pow(2,5)
- i.e. shift right 6 bits
EDIT - just noticed I dont offer the scale
option for single byte values (not sure why my node doesnt permit that!). So, for now, you will need to bit shift the byte values in a function node. So in otherwords, use the MASK options in the buffer parser (to drop bits you are not interested in) then in the function node, right shift the values by the required amount.
And what if the shift takes another byte? for instance.
00 00000000
59 00111011
preamble takes first 3 bits so:
stationtype takes the rest byte and part of the next with a total of 1 length so,
However, it doesn't work. I cannot offset 67 because it will pass a required byte.
The logic is:
pre stationtype other
000 00000001 11011
no bold offset 66 and bold offset 67. The value of stationtype should be 5, however, I'm getting values above 60
the mask is wrong.
^ This suggests the data is actually 16 bits - so we can use UINT16BE for both pre-amble and station type...
0xE000
and scale to 0.0001220703125
(shift right 13 bits)0x1FFF
and scale to 0
For some reason, the scale value in station type doesn't set to 0.
0
or 1
(doesnt matter)
0
means - dont scale.1
means multiply by 1 e.g. 1 x 100 == 100
, 1 x 69.123 = 69.123
, etc etc.It gives me value 89
Sorry, I am not psychic. I have no idea how your flow is written, nor what values you are sending in, nor do I know what value you should be getting.
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