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6116 Discussions

Shift ad Rotate with altmult_add

Honored Contributor II



To me it looks like Nios II does multiplication and shift/rotate with altmult_add on stratix iii, but when I look at the instantiation of the module in Nios II, it's not clear to me how it does shifting/rotation. Except two signals related to shift direction and shift/rotation mode, there's nothing there to request a shift/rotate operation rather than multiplication. Is there something I'm missing here? Any help is appreciated, thanks. 


Here's how Nios II uses altmult_add. 



altmult_add the_altmult_add 

.aclr0 (mul_clr), 

.aclr1 (mul_clr), 

.clock0 (clk), 

.clock1 (clk), 

.dataa (E_src1_mul_cell), 

.datab (E_src2_mul_cell), 

.ena0 (M_en), 

.ena1 (A_en), 

.result (A_mul_cell_result), 

.rotate (M_mul_cell_rotate), 

.shift_right (M_mul_cell_shift_right), 

.signa (E_ctrl_mul_shift_src1_signed), 

.signb (E_ctrl_mul_shift_src2_signed) 

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