[util] Add generic ecc encode function for re-use
Signed-off-by: Timothy Chen <timothytim@google.com>
[util] secded_gen fixes
Signed-off-by: Timothy Chen <timothytim@google.com>
diff --git a/util/design/secded_gen.py b/util/design/secded_gen.py
index f216565..93e2429 100755
--- a/util/design/secded_gen.py
+++ b/util/design/secded_gen.py
@@ -18,6 +18,8 @@
import random
import hjson
import subprocess
+from typing import Tuple
+from pathlib import Path
COPYRIGHT = """// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
@@ -76,6 +78,9 @@
# secded configurations
SECDED_CFG_FILE = "util/design/data/secded_cfg.hjson"
+PROJ_ROOT = Path(__file__).parent.joinpath('../../')
+SECDED_CFG_PATH = Path(PROJ_ROOT).joinpath(SECDED_CFG_FILE)
+
# The seed we use to initialise the PRNG when running the randomised algorithm
# to choose constants for Hsiao codes.
_RND_SEED = 123
@@ -317,6 +322,53 @@
return error
+def ecc_encode(codetype: str, k: int, dataword: int) -> Tuple[int, int]:
+ log.info(f"Encoding ECC for {hex(dataword)}")
+
+ # first check to see if bit width is supported among configuration
+ with open(SECDED_CFG_PATH, 'r') as infile:
+ config = hjson.load(infile)
+
+ codes = None
+ bitmasks = None
+ m = None
+ for cfg in config['cfgs']:
+ if cfg['k'] == k and cfg['code_type'] == codetype:
+ m = cfg['m']
+ codes = gen_code(codetype, k, m)
+ bitmasks = calc_bitmasks(k, m, codes, False)
+ break
+
+ # error if k not supported
+ if not m:
+ raise Exception(f'ECC for length {k} of type {codetype} unsupported')
+
+ # represent supplied dataword as a binary string
+ word_bin = format(dataword, '0' + str(k) + 'b')
+
+ codeword = word_bin
+ for j, mask in enumerate(bitmasks):
+ bit = 0
+ log.debug(f'codword: {codeword}')
+ log.debug(f'mask: {hex(mask)}')
+ mask = (format(mask, '0' + str(k + m) + 'b'))
+
+ # reverse codeword for index selection
+ # This is because the LSB is the farthest entry in the string
+ codeword_rev = codeword[::-1]
+ for idx, f in enumerate(mask[::-1]):
+ if int(f):
+ log.debug(f'xoring position {idx} value {codeword_rev[idx]}')
+ bit ^= int(codeword_rev[idx])
+
+ codeword = str(bit) + codeword
+
+ # Debug printouts
+ log.debug(f'original hex: {hex(dataword)}')
+ log.debug(f'codeword hex: {hex(int(codeword,2))}')
+ return int(codeword, 2), m
+
+
def gen_code(codetype, k, m):
# The hsiao_code generator uses (pseudo)random values to pick good ECC
# constants. Rather than exposing the seed, we pick a fixed one here to
