How to convert real to signed. The range of real will be from -1 to 1,
-5 to 5, -10 to 10 and so on. I would like to convert this range to a signed vector of bit width bw(generic). The data has to be scaled but I have no idea on how to do it. I have searched on the internet and did not find any valuable information.
You will need to know magnitude width and fraction width as you will be generating a fixed point decimal. Magnitude width (MW) can be done by taking log2(limit) and adding 1 (to account for the sign bit). Fraction width (FW) is then bw-MW.
Then you scale the result by 2**FW and convert it to an integer (which then gives you your signed number). Remember Integer(my_real) always rounds to nearest. If you dont want to round to nearest, you have to write a function that rounds to zero, otherwise removing the LSBs will always round down. (towards 0 for
You are ignoring what the MW and FW lengths of the real are, because it uses neither. For a real, which is floating point, its not magnitude and fraction widths, its mantissa and exponent. You are specified what YOU want the real to fit in to. You are making a FIXED POINT decimal value, so MW and FW never change. for example:
from 3 to -3
you need MW = 3 (1 sign bit an 1 other bit) FW = how ever many you want. each bit represets 2^-n (with n=0 to the left of the imaginary point)
so 0.75 is represended by: 000.1100000 = 2^-1 (0.5) + 2^-2 (0.25)
-1.75 = 110.01111111 (invert all bits and add one to number above) etc etc All values are 2s compliment, and can then be used in any standard adder, multiplier etc on firmware. Just make sure you use the correct bits of the result:
a 2.6 number x 6.2 number = 8.8 result
a a . a a a a a a b b b b b b . b b = r r r r r r r r . r r r r r r r r