Xilinx
TM
Block Preview

Introduction

This block computes the reciprocal (multiplicative inverse) of IEEE 754 floating-point values using the Xilinx Floating Point IP core. The component supports Time Multiplexing (TM): multiple parallel computation units share the same clock cycle.

On every rising edge of CLK, if DIN_VLD = 1 and DOUT_RDY = 1:

$$ \mathrm{DOUT}(n) = \frac{1}{\mathrm{DIN}(n)} $$

Pin Description

DIN Input Variable bit TM
Floating-point input, always TM. Should not be zero.
Default: Must be connected
DIN_VLD Input 1 bit BIT
Input data valid.
DIN_RDY Output 1 bit BIT
Input ready output.
CLK Input 1 bit BIT
Global clock.
Default: Default Board Clock
DOUT Output Variable bit TM
Reciprocal output (1/DIN). Valid after 30 cycles.
DOUT_VLD Output 1 bit BIT
Output data valid.
DOUT_RDY Input 1 bit BIT
Downstream ready signal.

Properties

Property window

TM Factor TMFactor

Time Multiplexing factor (number of phases)

Number of TM phases (1 – 32).

Default: 4

Range: 1 – 32

Float Format FloatFormat

Select between single precision 32 bit and double precision 64 bit

Single or Double precision.

Default: Single

Options: Single Double

DSP Usage DSPUsage

DSP Usage. Single precision: No [0], Full[8]. Double precision: No[0], Full[14]

  • No_Usage or Full_Usage Single: 0/8 DSPs; Double: 0/14 DSPs

Default: Full_Usage

Options: No_Usage Full_Usage

Functional description

Wraps Xilinx Floating Point IP (operation type: Reciprocal) with N parallel instances for TM support.

Mathematical background

Reciprocal function:

$$ y = \frac{1}{x} = x^{-1} $$

Special cases:

  • $\frac{1}{1} = 1$
  • $\frac{1}{\infty} = 0$
  • $\frac{1}{0} = \infty$
  • $\frac{1}{-x} = -\frac{1}{x}$

Properties:

  • $\frac{1}{1/x} = x$
  • $\frac{1}{xy} = \frac{1}{x} \cdot \frac{1}{y}$

Timing

Fixed latency of 30 clock cycles per phase.

Property Latency (cycles)
Reciprocal 30

DSP Usage

  • Single precision: No [0], Full[8]
  • Double precision: No[0], Full[14]

Typical use cases

  • Division replacement (faster than general division)
  • Normalization
  • Gain inversion
  • Impedance calculations
  • Newton-Raphson iterations