// SPDX-License-Identifier: GPL-2.0+
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/*
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* Generate a table for CRC-32C calculation.
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*
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* Copyright (C) 2018 Google LLC
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*
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* Written by Eric Biggers.
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*/
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#include <stdint.h>
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#include <stdio.h>
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/*
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* This is the CRC-32C (Castagnoli) polynomial: x^32+x^28+x^27+x^26+x^25+x^23+
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* x^22+x^20+x^19+x^18+x^14+x^13+x^11+x^10+x^9+x^8+x^6+x^0, with the polynomial
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* coefficients mapped to bits using the "little endian" convention.
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*/
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#define CRC32C_POLY_LE 0x82F63B78
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static uint32_t crc32c_update_bit(uint32_t remainder, uint8_t bit)
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{
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return (remainder >> 1) ^
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(((remainder ^ bit) & 1) ? CRC32C_POLY_LE : 0);
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}
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static uint32_t crc32c_update_byte(uint32_t remainder, uint8_t byte)
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{
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int bit;
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for (bit = 0; bit < 8; bit++, byte >>= 1)
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remainder = crc32c_update_bit(remainder, byte & 1);
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return remainder;
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}
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static uint32_t crc32c_table[256];
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int main(void)
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{
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int i, j;
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for (i = 0; i < 256; i++)
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crc32c_table[i] = crc32c_update_byte(0, i);
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printf("/*\n");
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printf(" * crc32c_table.h - data table to accelerate CRC-32C computation\n");
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printf(" *\n");
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printf(" * This file was automatically generated by scripts/gen_crc32c_table.c\n");
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printf(" */\n");
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printf("\n");
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printf("#include <stdint.h>\n");
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printf("\n");
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printf("static const uint32_t crc32c_table[] = {\n");
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for (i = 0; i < 64; i++) {
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printf("\t");
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for (j = 0; j < 4; j++) {
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printf("0x%08x,", crc32c_table[i * 4 + j]);
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if (j != 3)
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printf(" ");
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}
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printf("\n");
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}
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printf("};\n");
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return 0;
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}
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