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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (c) 2024, The Linux Foundation. All rights reserved.
*/
#include <linux/types.h>
#include "dp_utils.h"
#define DP_SDP_HEADER_SIZE 8
u8 dp_utils_get_g0_value(u8 data)
{
u8 c[4];
u8 g[4];
u8 ret_data = 0;
u8 i;
for (i = 0; i < 4; i++)
c[i] = (data >> i) & 0x01;
g[0] = c[3];
g[1] = c[0] ^ c[3];
g[2] = c[1];
g[3] = c[2];
for (i = 0; i < 4; i++)
ret_data = ((g[i] & 0x01) << i) | ret_data;
return ret_data;
}
u8 dp_utils_get_g1_value(u8 data)
{
u8 c[4];
u8 g[4];
u8 ret_data = 0;
u8 i;
for (i = 0; i < 4; i++)
c[i] = (data >> i) & 0x01;
g[0] = c[0] ^ c[3];
g[1] = c[0] ^ c[1] ^ c[3];
g[2] = c[1] ^ c[2];
g[3] = c[2] ^ c[3];
for (i = 0; i < 4; i++)
ret_data = ((g[i] & 0x01) << i) | ret_data;
return ret_data;
}
u8 dp_utils_calculate_parity(u32 data)
{
u8 x0 = 0;
u8 x1 = 0;
u8 ci = 0;
u8 iData = 0;
u8 i = 0;
u8 parity_byte;
u8 num_byte = (data & 0xFF00) > 0 ? 8 : 2;
for (i = 0; i < num_byte; i++) {
iData = (data >> i * 4) & 0xF;
ci = iData ^ x1;
x1 = x0 ^ dp_utils_get_g1_value(ci);
x0 = dp_utils_get_g0_value(ci);
}
parity_byte = x1 | (x0 << 4);
return parity_byte;
}
ssize_t dp_utils_pack_sdp_header(struct dp_sdp_header *sdp_header, u32 *header_buff)
{
size_t length;
length = sizeof(header_buff);
if (length < DP_SDP_HEADER_SIZE)
return -ENOSPC;
header_buff[0] = FIELD_PREP(HEADER_0_MASK, sdp_header->HB0) |
FIELD_PREP(PARITY_0_MASK, dp_utils_calculate_parity(sdp_header->HB0)) |
FIELD_PREP(HEADER_1_MASK, sdp_header->HB1) |
FIELD_PREP(PARITY_1_MASK, dp_utils_calculate_parity(sdp_header->HB1));
header_buff[1] = FIELD_PREP(HEADER_2_MASK, sdp_header->HB2) |
FIELD_PREP(PARITY_2_MASK, dp_utils_calculate_parity(sdp_header->HB2)) |
FIELD_PREP(HEADER_3_MASK, sdp_header->HB3) |
FIELD_PREP(PARITY_3_MASK, dp_utils_calculate_parity(sdp_header->HB3));
return length;
}
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