DSP Builder for Intel® FPGAs (Advanced Blockset): Handbook
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15.3.23. Twiddle Angle (TwiddleAngle)
The TwiddleAngle block takes the output of the counter and splits it into three parts:
- The channel field (LSBs of the counter)
- The index field
- The pivot field (MSBs of the counter)
It provides bitreverse(pivot) * index at the output. The calculation is optimized to use no multipliers and only a small amount of logic.
The TwiddleAngle block has an additional input: v, which keeps the internal state of the TwiddleAngle block synchronized with the counter. This input should be identical to the enable input to the counter.
Parameter | Description |
---|---|
K | Width of the channel field. |
Pivot width | Width of the pivot field. |
Index width | Width of the index field. |
Signal | Direction | Type | Description |
---|---|---|---|
v | Input | Boolean | Input to upcounter. |
c | Input | Unsigned integer | Output of upcounter. |
angle | Output | Unsigned integer | Input to TwiddleRom. |