3.4.3. Pre-Adder for Fixed-Point Arithmetic
Each variable precision DSP block has two 19-bit pre-adders. You can configure these pre-adders in the following configurations:
- Two independent 19-bit pre-adders
- One 27-bit pre-adder
The pre-adder supports both addition and subtraction in the following input configurations:
- 18-bit (signed or unsigned) addition or subtraction for 18 x 19 mode
- 26-bit addition or subtraction for 27 x 27 mode
When both pre-adders within the same DSP block are used, they must share the same operation type (either addition or subtraction).