The golden reference used (adc_val - 128) << 9 which subtracts 65536,
but the Verilog RTL computes {1'b0,adc,9'b0} - {1'b0,8'hFF,9'b0}/2
which subtracts 0xFF00 = 65280. This creates a constant 256-LSB DC
offset between the golden reference and RTL for all 256 ADC values.
The bit-accurate model in fpga_model.py already uses the correct RTL
formula. This aligns golden_reference.py to match.
Verified: all 256 ADC input values now produce zero offset against
fpga_model.py.
JunghwanNA
a9ceb3c851