1.4.4.3 Fract_10toX_Q15bfpFromQ15d16 Function

fract_q15bfp_t Fract_10toX_Q15bfpFromQ15d16( fract_q15d16_t x )

Summary

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

Description

Calculates pow(2,x) using fixed point math, with x as Q15.16, returning result as Q15 block floating point.

Preconditions

None.

Parameters

x exponent as Q15.16

Returns

pow(2,x) as Q15 block floating point

Remarks

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

Example

fract_q15bfp_t Y;

x = 0x00008000; _// 0.5_

Y = Fract_10toX_Q15bfpFromQ15d16(x);

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

_// Y.e = 2_

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

x = 0x0003243F; _// 205,887 / 65536 = 3.141586 (vs. 3.14159)_

Y = Fract_10toX_Q15bfpFromQ15d16(x);

_// Y.m = 0x5696 = 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_Q15bfpFromQ15d16 (fract_q15d16_t x );