ALTERA_CORDIC IP Core User Guide

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ID 683808
Date 5/08/2017
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Document Table of Contents
Document Table of Contents x
1. ALTERA_CORDIC IP Core User Guide
1. ALTERA_CORDIC IP Core User Guide x
1.1. ALTERA_CORDIC IP Core Features 1.2. DSP IP Core Device Family Support 1.3. ALTERA_CORDIC IP Core Functional Description 1.4. ALTERA_CORDIC IP Core Parameters 1.5. ALTERA_CORDIC IP Core Signals
1.3. ALTERA_CORDIC IP Core Functional Description x
1.3.1. SinCos Function 1.3.2. Atan2 Function 1.3.3. Vector Translate Function 1.3.4. Vector Rotate Function
1. ALTERA_CORDIC IP Core User Guide

1.3.4. Vector Rotate Function

The vector rotate function takes a vector v= (x,y) T given by the two coordinates x and y and an angle a. The function produces a similarity rotation of vector v by the angle a to produce the vector v0=(x0, y0) T .
Figure 4. Vector Rotate Function

The rotation is a similarity rotation because the magnitude of the produced vector v0 is scaled up by the CORDIC specific constant K(˜1.646760258121). The equations of the coordinates for vector v0 are:

  • x0 = K(xcos(a)− ysin(a))
  • y0 = K(xsin(a)+ ycos(a))

If you set the sign attribute to true for the x,y inputs for the function, the IP core restricts their range to [−1,1]. You provide the number of fractional bits. The input angle a is allowed in the range [−π,+π], and has the same number of fractional bits as the other inputs. You provide the output fractional bits and the total width of the output is w=wF+3, signed. For unsigned inputs x,y, the IP core restricts the range to [0,1], the angle a to [0,π].

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