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Embedded Software and Motor Control Libraries for PXR40xx

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Subtraction of two fractional 16-bit values. The second argument is subtracted from the<br />

first one. The input values as well as output value are considered as 16-bit fractional data<br />

type. The output saturation is not implemented in this function, thus in case the<br />

subtraction of input parameters is outside the (-1, 1) interval, the output value will<br />

overflow without any detection.<br />

Overflow is not detected.<br />

4.176.5 Re-entrancy<br />

The function is re-entrant.<br />

4.176.6 Code Example<br />

#include "mlib.h"<br />

tFrac16 f16In1;<br />

tFrac16 f16In2;<br />

tFrac16 f16Out;<br />

void main(void)<br />

{<br />

// first input = 0.5<br />

f16In1 = FRAC16 (0.5);<br />

}<br />

// second input = 0.25<br />

f16In2 = FRAC16 (0.25);<br />

Note<br />

// output should be 0x2000<br />

f16Out = MLIB_Sub_F16(f16In1,f16In2);<br />

// output should be 0x2000<br />

f16Out = MLIB_Sub (f16In1,f16In2,Define F16);<br />

// ##############################################################<br />

// Available only if 16-bit fractional implementation selected<br />

// as default<br />

// ##############################################################<br />

// output should be 0x20000000<br />

f16Out = MLIB_Sub (f16In1,f16In2);<br />

The output of the function is defined by the following simple equation:<br />

Overflow is not detected.<br />

Equation MLIB_Sub_Eq1<br />

Note<br />

<strong>Embedded</strong> <strong>Software</strong> <strong>and</strong> <strong>Motor</strong> <strong>Control</strong> <strong>Libraries</strong> <strong>for</strong> <strong>PXR40xx</strong>, Rev. 1.0<br />

Chapter 4 API References<br />

Freescale Semiconductor, Inc. 665

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