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88 lines
2.9 KiB
C
88 lines
2.9 KiB
C
/*
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* SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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//
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// Serially shift {data_in,lfsr_cur} N times to get {lfsr_next}
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//
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static uint32_t lfsr_serial_shift_crc(uint32_t data_in, uint32_t lfsr_cur,
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size_t crc_width, uint32_t crc_poly_hex,
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size_t num_bits_to_shift)
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{
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uint32_t lfsr_next = lfsr_cur;
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for (int j = 0; j < num_bits_to_shift; j++) {
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uint32_t lfsr_upper_bit = lfsr_next >> (crc_width - 1);
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// shift the entire LFSR
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for (int i = crc_width - 1; i > 0; i--) {
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lfsr_next &= ~(1 << i);
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if (crc_poly_hex & (1 << i)) {
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// lfsr_next[i] = lfsr_next[i - 1] ^ lfsr_upper_bit ^ data_in[j];
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lfsr_next |= (((lfsr_next >> (i - 1)) ^ lfsr_upper_bit ^ (data_in >> j)) & 0x01) << i;
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} else {
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// lfsr_next[i] = lfsr_next[i - 1];
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lfsr_next |= (lfsr_next & (1 << (i - 1))) << 1;
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}
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}
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// lfsr_next[0] = lfsr_upper_bit ^ data_in[j];
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lfsr_next &= ~0x01;
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lfsr_next |= (lfsr_upper_bit ^ (data_in >> j)) & 0x01;
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}
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return lfsr_next;
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}
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void gdma_hal_build_parallel_crc_matrix(int crc_width, uint32_t crc_poly_hex, int data_width,
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uint32_t *lfsr_transform_matrix, uint32_t *data_transform_matrix)
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{
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int N = crc_width;
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int M = data_width;
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uint32_t lfsr_cur = 0; // N-bit LFSR
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uint32_t lfsr_next = 0; // N-bit LFSR
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uint32_t data_in = 0; // M-bit data
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// LFSR-2-LFSR matrix[NxN], data_in=0
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for (int n1 = 0; n1 < N; n1++) {
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lfsr_cur = 1 << n1;
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lfsr_next = lfsr_serial_shift_crc(data_in, lfsr_cur,
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crc_width, crc_poly_hex,
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data_width);
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lfsr_transform_matrix[n1] = lfsr_next;
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}
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// Data-2-LFSR matrix[MxN], lfsr_cur=0
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lfsr_cur = 0;
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for (int m1 = 0; m1 < M; m1++) {
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data_in = 1 << m1;
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lfsr_next = lfsr_serial_shift_crc(data_in, lfsr_cur,
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crc_width, crc_poly_hex,
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data_width);
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// Invert CRC data bits
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data_transform_matrix[M - m1 - 1] = lfsr_next;
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}
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}
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uint32_t gdma_hal_get_data_mask_from_matrix(uint32_t *data_transform_matrix, int data_width, int crc_bit)
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{
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uint32_t data_mask = 0;
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for (int j = 0; j < data_width; j++) {
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data_mask |= (data_transform_matrix[j] & (1 << crc_bit)) ? (1 << j) : 0;
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}
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return data_mask;
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}
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uint32_t gdma_hal_get_lfsr_mask_from_matrix(uint32_t *lfsr_transform_matrix, int crc_width, int crc_bit)
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{
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uint32_t lfsr_mask = 0;
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for (int j = 0; j < crc_width; j++) {
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lfsr_mask |= (lfsr_transform_matrix[j] & (1 << crc_bit)) ? (1 << j) : 0;
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}
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return lfsr_mask;
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}
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