IQmath Library

IQNmpyI32int
Integer portion of (IQN*LONG)
Description
Declaration
This function multiplies an IQ number with a long integer and returns the
integer part of the result.
Global IQ function (IQ format = GLOBAL_Q)
long _IQmpyI32int(_iq A, long B)
Q format specific IQ function (IQ format = IQ1 to IQ30)
long _IQNmpyI32int( _iqN A, long B)
Input Format
Global IQ function (IQ format = GLOBAL_Q)
Operand “A” is an IQ number in GLOBAL_Q format and “B” is the long
integer.
Q format specific IQ function (IQ format = IQ1 to IQ30)
Operand “A” is an IQ number in IQN format and “B” is the long integer.
Output Format
Global IQ function (IQ format = GLOBAL_Q)
Integer part of the result (32-bit)
Q format specific IQ function (IQ format = IQ1 to IQ30)
Integer part of the result (32-bit)
Usage
Example 1:
Convert an IQ value in the range [- 1.0, +1.0] to a DAC value with the
range [ 0 to 1023]:
_iq Output;
long temp;
short OutputDAC;
temp = _IQmpyI32int(Output, 512); // value converted to +/- 512
temp += 512; // value scaled to 0 to 1023
if( temp > 1023 )
temp = 1023;
// saturate within range of DAC
if( temp < 0 )
temp = 0;
OutputDAC = (int )temp;
// output to DAC value
Note: The integer operation performs the multiply and calculates the
integer portion from the resulting 64-bit calculation. Hence it avoids any
overflow conditions.
©Texas Instruments Inc., June 2002 27