1.4.4.2 Fract_10toX_Q15bfp Function

fract_q15bfp_t Fract_10toX_Q15bfp( fract_q15bfp_t x )

Summary

Calculates pow(2,x) with fixed point math.

Description

Calculates pow(2,x) using fixed point math, with x as Q15 block floating point, returning the result in the same format.

Preconditions

None.

Parameters

x exponent, in Q15 block floating point format

Returns

pow(2,x), in Q15 block floating point format

Remarks

Fract_10toX(x) is basically Fract_2toX( log2(10)*x ).

Example

fract_q15bfp_t X,Y;

X.m = 0x4000; _// 1/2_

X.e = 0;

Y = Fract_10toX_Q15bfp(X);

_// Y.m = 0x6532 = 25906_

_// Y.e = 2_

_// Y = ( 25906 / 32768 )&lt;&lt;2 = 3.162353 (vs. 3.162277) , rel error = 1/41688_

X.m = 0x6488; _// (3.14159/4)_

X.e = 2;

Y = Fract_10toX_Q15bfp(X);

_// Y.m = 0x5697 = 22167 / 32768 = 0.676483_

_// Y.e = 0x000B = 11_

_// Y = (22167 / 32768)&lt;&lt;11 = 1385.4375 (vs. 1385.435475), rel error = 1/684,023_

fract_q15bfp_t Fract_10toX_Q15bfp (fract_q15bfp_t x );