IQmath Library

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IQsat Saturate the IQ number Description This intrinsic saturates an IQ value to the given Positive and Negative limits. This operation is useful in areas where there is potential for overflow in a calculation. Declaration _iq _IQsat(_iq A, long P, long N) Input Format Output Format Global IQ function (IQ format = GLOBAL_Q) IQ number in GLOBAL_Q format Global IQ function (IQ format = GLOBAL_Q) Absolute value of input in GLOBAL_Q format Usage Example: Calculate the linear equation "Y = M*X + B", with saturation. All variables are GLOBAL_Q = 26. However, there is a possibility that the variable ranges may cause overflow, so we must perform the calculation and saturate the result. To do this, we perform the intermediate operations using IQ = 20 and then saturate before converting the result back to the appropriate GLOBAL_Q value: _iq Y, M, X, B; _iq20 temp; // GLOBAL_Q = 26 (+/- 32 range) // IQ = 20 (+/- 2048 range) temp = _IQ20mpy(_IQtoIQ20(M), _IQtoIQ20(X)) + _IQtoIQ20(B); temp = _IQsat(temp, _IQtoIQ20(MAX_IQ_POS), _IQtoIQ20(MAX_IQ_NEG)); Y = _IQ20toIQ(temp); ©Texas Instruments Inc., June 2002 64
Appendix A: <strong>IQmath</strong> C-Calling Convention All the <strong>IQmath</strong> function strictly adheres to C28x C-Calling convention. To understand the C28x C- Calling convention, Please refer Chapter 7 (Run-time Environment) of TMC320C28x Optimizing C/C++ Compiler User's Guide (SPRU514). ©Texas Instruments Inc., June 2002 65
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IQmath Library A Virtual Floating P
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IMPORTANT NOTICE Texas Instruments
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Contents 1. Introduction………
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Function Name C28x IQmath LIBRARY B
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Chapter 1: Introduction 1.1. Introd
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Chapter 3: Using IQmath Library 3.1
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3.3. Calling a IQmath Function from
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CASE II : A complete system consist
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Chapter 4: Function Summary The rou
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Trignometric Functions: Functions D
Page 21 and 22: Chapter 5: Function Description ©T
Page 23 and 24: IQNtoF Float to IQN data type Descr
Page 25 and 26: IQNint Integer part of IQN number D
Page 27 and 28: IQtoIQN GLOBAL_Q number to IQN Desc
Page 29 and 30: IQtoQN GLOBAL_Q number to QN Descri
Page 31 and 32: IQNmpy IQ Multiplication(IQN*IQN) D
Page 33 and 34: IQNrsmpy IQ Multiplication with rou
Page 35 and 36: IQNmpyI32int Integer portion of (IQ
Page 37 and 38: IQNmpyIQX Multiplication (GLOBAL_Q=
Page 39 and 40: C/C-Callable ASM Interface C/C-Call
Page 41 and 42: Fixed Point vs Floating Point Analy
Page 43 and 44: C-Callable ASM Interface C-Callable
Page 45 and 46: IQNsinPU Description Fixed point SI
Page 47 and 48: IQNsinPU Function vs C Float SIN: I
Page 49 and 50: C-Callable ASM Interface C-Callable
Page 51 and 52: IQNcosPU Fixed point COS (radians i
Page 57 and 58: IQNatan2PU Description Fixed point
Page 65 and 66: IQNisqrt Fixed point Inverse Square
Page 69 and 70: IQNmag Magnitude of IQ complex numb
Page 71: IQNabs Absolute value of IQ number
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IQmath Library

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