Q15 to decimal converter

Silmple function that converts an value from Q15 to decimal.

Description

Converts any Q15 value (hexadecimal or binary) to decimal integer.

y = q152dec(x , form)

Input arguments of function:
x - its hexadecimal or binary representation stored in a MATLAB string

form - dependent on representation of input argument (hexadecimal or binary) take 'hex' or 'bin'

Valu of function:
y - decimal integer

EXAMPLE:
>> q152dec('C000','hex')

ans =

   -0.5000

• MATLAB release: MATLAB 7.4 (R2007a)

[Jos x@y.z]

Please add a proper help section, including a H1 line, input and output requirements, and an example as well as internal comments, if you want that anyone else but you will find this code useful.

[A B]

VERY USEFUL, Thank you.

[Dave Hardell]

Unfortunately for me, this solution requires the fixed-point toolbox (for bin2num, or hex2num). This is my solution:
decimal to Q15:

y=int16(x*2^15);
% then use dec2hex(y) if you want hex format

Q15 to decimal:

% use hex2dec(x) first if x is in hex format
x=double(x);
y=x*2^-15;

Is there any reason this should not work?

Dave

[Szymon Leja]

Dave Your solutions are good but only for positive numbers.

decimal to Q15 -> dec2hex(y) -> y must be a nonnegative integer.

Q15 to decimal -> for negative numbers return wrong result.

Best regards,
S.L.