TM
Block Preview

Introduction

This block performs one-fill bit extension on time-multiplexed (TM) data streams. It extends the input word to a wider output format by appending ones (1s), useful for creating bit masks and special numeric formats.

The operation is purely combinational with zero latency. Ones can be added to either:

  • MSB side (RIGHT alignment)
  • LSB side (LEFT alignment)

The TM Factor property determines how many parallel samples are processed per clock cycle.

Pin Description

IN Input Variable bit TM
Input binary data, always TM. Width: Input Width × TM Factor
Default: Must be connected
OUT Output Variable bit TM
One-extended output, always TM. Width: Output Size × TM Factor Output is combinational (zero latency).

Properties

Property window

Input Width (per phase) InputWidth

Set the input word size in bits per phase

Number of bits per input sample. Range: 2 – 128. Must be ≤ Output Size.

Default: 16

Range: 2 – 128

TM Factor TMFactor

Set the time multiplexing factor (number of phases)

Time-multiplexing factor (number of parallel phases). Allowed values: 2, 4, 8, 16, 32.

Default: 4

Range: 2 – 32

Output Size (per phase) OutputSize

Set the output word size in bits per phase

Number of bits per output sample. Range: 0 – 128. Must be ≥ Input Width. Number of ones added = Output Size - Input Width.

Default: 32

Range: 0 – 128

Vector Align Align

Select if output should be aligned on right (Ones fill the MSBs) or LEFT

Alignment mode:

  • RIGHT: Input in LSBs, ones in MSBs
  • LEFT: Input in MSBs, ones in LSBs

Default: RIGHT

Options: RIGHT LEFT

Functional description

The component implements one-fill extension in VHDL, replicated N times (where N = TM Factor) to support time-multiplexed data streams.

For each TM phase:

  • Input width = Input Width bits
  • Output width = Output Size bits (must be ≥ Input Width)
  • Padding = Output Size - Input Width one bits

Alignment modes

  • RIGHT alignment (default):

    • Input is placed in the LSBs (rightmost bits)
    • Ones fill the MSBs (leftmost bits)
    • Example: 8-bit 11010110 → 16-bit 11111111 11010110

  • LEFT alignment:

    • Input is placed in the MSBs (leftmost bits)
    • Ones fill the LSBs (rightmost bits)
    • Example: 8-bit 11010110 → 16-bit 11010110 11111111

Mathematical background

One-fill is commonly used for:

  • Creating bit masks with specific patterns
  • Ones’ complement operations
  • Special fixed-point formats
  • Bit field manipulation

Timing

The component is purely combinational with zero latency:

Property Latency (clock cycles)
One Fill TM 0

All TM phases are processed in parallel within the same clock cycle.

Typical use cases

  • Bit mask generation
  • Ones’ complement number formatting
  • Special bit pattern creation
  • Protocol-specific data formatting