Column Processing Element (pe_col.sv)

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Source file: rtl/systolic_gauss_jordan/pe_col.sv

Elementary Processing element used across the systolic mesh Trapezoidal mesh (trapeziod_mesh.sv) which processes incoming columns (non-pivot members of each row). The opcode (op_o/op_i) enums are defined in Shared package (gj_pkg.sv)

Ports

Inputs

• clk: clock signal

• rst: reset

• en_i: enable

• data_i: data bit in

• op_i: op signal in

Outputs

• op_o: op signal out

• data_o: data bit out

• state_o: internal register state out

Behaviour

• receives opcodes (op_o/op_i) from pivot element (Trapezoidal mesh (pe_diag.sv)) which are transferred horizontally

• receives data bits (data_in) vertically which are used to update internal register r and determine data_out based on opcodes.

Transition table

Notes:

• r is the current stored bit.

• r_next is the next stored bit.

• data_o_next is the combinational value later registered into data_o.

• op_o is the registered copy of op_i when rst = 0 and en_i = 1.

Enabled data path (rst = 0, en_i = 1)

op_i	data_i	r	r_next	data_o_next	op_o after clock	Meaning
OP_PASS	data_i	r	r	data_i	OP_PASS	Forward vertical data unchanged
OP_SWAP	data_i	r	data_i	r	OP_SWAP	Emit stored bit and load incoming bit
OP_LOCK	data_i	r	data_i	r	OP_LOCK	Same local state update as OP_SWAP
OP_ADD	data_i	r	r	r ^ data_i	OP_ADD	Add incoming bit into the vertical stream over GF(2)
default	data_i	r	r	data_i	op_i	Fallback behaves like pass

Test

• Test file: test_pe_col.py verifies truth table

make -C test/systolic_gauss_jordan TEST=pe_col