From d9f7ae48823b549894e1446da1a0d082e56a1c5b Mon Sep 17 00:00:00 2001 From: Florent Kermarrec Date: Tue, 26 Mar 2024 10:48:18 +0100 Subject: [PATCH] mac/crc: Another cleanup pass. --- liteeth/mac/crc.py | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/liteeth/mac/crc.py b/liteeth/mac/crc.py index d27a101..794d6f5 100644 --- a/liteeth/mac/crc.py +++ b/liteeth/mac/crc.py @@ -33,27 +33,29 @@ class LiteEthMACCRCEngine(LiteXModule): The polynomial used for the CRC calculation, specified as an integer (e.g., 0x04C11DB7 for IEEE 802.3). """ def __init__(self, data_width, width, polynom): - self.data = Signal(data_width) - self.crc_prev = Signal(width) - self.crc_next = Signal(width) + self.data = Signal(data_width) # Data (Input). + self.crc_prev = Signal(width) # CRC Previous (Input). + self.crc_next = Signal(width) # CRC Next (Output). # # # - # compute and optimize the parallel implementation of the CRC's LFSR - taps = [x for x in range(width) if (1 << x) & polynom] - curval = [[("state", i)] for i in range(width)] - for i in range(data_width): - feedback = curval.pop() + [("din", i)] - for j in range(width-1): - if j+1 in taps: - curval[j] += feedback - curval[j] = self.optimize_xors(curval[j]) - curval.insert(0, feedback) + # Determine bits affected by the polynom. + polynom_taps = [bit for bit in range(width) if (1 << bit) & polynom] - # implement logic + # Prepare the list for CRC calculation through LFSR. + crc_bits = [[("state", i)] for i in range(width)] + for n in range(data_width): + feedback = crc_bits.pop(-1) + [("din", n)] + for pos in range(width - 1): + if (pos + 1) in polynom_taps: + crc_bits[pos] += feedback + crc_bits[pos] = self.optimize_xors(crc_bits[pos]) + crc_bits.insert(0, feedback) + + # Calculate the next CRC value based on XOR operations. for i in range(width): xors = [] - for t, n in curval[i]: + for t, n in crc_bits[i]: if t == "state": xors += [self.crc_prev[n]] elif t == "din":