138 8-bit carry-skip
138 : 8-bit carry-skip
- Author: Dennis_Du
- Description: two 8-bit input adder
- GitHub repository
- Open in 3D viewer
- Clock: 0 Hz
How it works
This project implements an 8-bit carry-skip adder using a combination of ripple-carry and skip logic for enhanced performance. The adder is divided into two 4-bit sections. The lower 4 bits compute the initial partial sum and generate a carry-out, which is then either passed directly to the upper 4-bit section or skipped, depending on the carry-propagate signal. This design reduces the delay associated with carry propagation, making it more efficient than a conventional ripple-carry adder. The final 8-bit sum is registered and outputted in sync with the clock signal.
How to test
To test the carry-skip adder:
- Load the design into your simulation environment.
- Set the
ui_inanduio_ininputs with the desired 8-bit values for addition. - The result of the addition will appear on
uo_outafter each rising edge. - Verify that the output matches expected values by comparing
uo_outwith the sum of the inputs.
For more extensive testing, a testbench can be used to automate input combinations and check results across various cases.
External hardware
No external hardware is required for this project.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | a[0] | sum[0] | b[0] |
| 1 | a[1] | sum[1] | b[1] |
| 2 | a[2] | sum[2] | b[2] |
| 3 | a[3] | sum[3] | b[3] |
| 4 | a[4] | sum[4] | b[4] |
| 5 | a[5] | sum[5] | b[5] |
| 6 | a[6] | sum[6] | b[6] |
| 7 | a[7] | sum[7] | b[7] |