diff options
Diffstat (limited to 'scripts/gen-crc-consts.py')
| -rwxr-xr-x | scripts/gen-crc-consts.py | 55 |
1 files changed, 54 insertions, 1 deletions
diff --git a/scripts/gen-crc-consts.py b/scripts/gen-crc-consts.py index aa678a50897d..f9b44fc3a03f 100755 --- a/scripts/gen-crc-consts.py +++ b/scripts/gen-crc-consts.py @@ -105,6 +105,57 @@ def gen_slicebyN_tables(variants, n): print(f'\t{s}') print('};') +def print_riscv_const(v, bits_per_long, name, val, desc): + print(f'\t.{name} = {fmt_poly(v, val, bits_per_long)}, /* {desc} */') + +def do_gen_riscv_clmul_consts(v, bits_per_long): + (G, n, lsb) = (v.G, v.bits, v.lsb) + + pow_of_x = 3 * bits_per_long - (1 if lsb else 0) + print_riscv_const(v, bits_per_long, 'fold_across_2_longs_const_hi', + reduce(1 << pow_of_x, G), f'x^{pow_of_x} mod G') + pow_of_x = 2 * bits_per_long - (1 if lsb else 0) + print_riscv_const(v, bits_per_long, 'fold_across_2_longs_const_lo', + reduce(1 << pow_of_x, G), f'x^{pow_of_x} mod G') + + pow_of_x = bits_per_long - 1 + n + print_riscv_const(v, bits_per_long, 'barrett_reduction_const_1', + div(1 << pow_of_x, G), f'floor(x^{pow_of_x} / G)') + + val = G - (1 << n) + desc = f'G - x^{n}' + if lsb: + val <<= bits_per_long - n + desc = f'({desc}) * x^{bits_per_long - n}' + print_riscv_const(v, bits_per_long, 'barrett_reduction_const_2', val, desc) + +def gen_riscv_clmul_consts(variants): + print('') + print('struct crc_clmul_consts {'); + print('\tunsigned long fold_across_2_longs_const_hi;'); + print('\tunsigned long fold_across_2_longs_const_lo;'); + print('\tunsigned long barrett_reduction_const_1;'); + print('\tunsigned long barrett_reduction_const_2;'); + print('};'); + for v in variants: + print(''); + if v.bits > 32: + print_header(v, 'Constants') + print('#ifdef CONFIG_64BIT') + print(f'static const struct crc_clmul_consts {v.name}_consts __maybe_unused = {{') + do_gen_riscv_clmul_consts(v, 64) + print('};') + print('#endif') + else: + print_header(v, 'Constants') + print(f'static const struct crc_clmul_consts {v.name}_consts __maybe_unused = {{') + print('#ifdef CONFIG_64BIT') + do_gen_riscv_clmul_consts(v, 64) + print('#else') + do_gen_riscv_clmul_consts(v, 32) + print('#endif') + print('};') + # Generate constants for carryless multiplication based CRC computation. def gen_x86_pclmul_consts(variants): # These are the distances, in bits, to generate folding constants for. @@ -213,7 +264,7 @@ def parse_crc_variants(vars_string): if len(sys.argv) != 3: sys.stderr.write(f'Usage: {sys.argv[0]} CONSTS_TYPE[,CONSTS_TYPE]... CRC_VARIANT[,CRC_VARIANT]...\n') - sys.stderr.write(' CONSTS_TYPE can be sliceby[1-8] or x86_pclmul\n') + sys.stderr.write(' CONSTS_TYPE can be sliceby[1-8], riscv_clmul, or x86_pclmul\n') sys.stderr.write(' CRC_VARIANT is crc${num_bits}_${bit_order}_${generator_poly_as_hex}\n') sys.stderr.write(' E.g. crc16_msb_0x8bb7 or crc32_lsb_0xedb88320\n') sys.stderr.write(' Polynomial must use the given bit_order and exclude x^{num_bits}\n') @@ -232,6 +283,8 @@ variants = parse_crc_variants(sys.argv[2]) for consts_type in consts_types: if consts_type.startswith('sliceby'): gen_slicebyN_tables(variants, int(consts_type.removeprefix('sliceby'))) + elif consts_type == 'riscv_clmul': + gen_riscv_clmul_consts(variants) elif consts_type == 'x86_pclmul': gen_x86_pclmul_consts(variants) else: |