gp_bit_swap.h

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// SPDX-License-Identifier: LGPL-2.1-or-later
/*
 * Copyright (C) 2012 Cyril Hrubis <metan@ucw.cz>
 */
 
#ifndef CORE_GP_BIT_SWAP_H
#define CORE_GP_BIT_SWAP_H
 
static inline uint8_t GP_BIT_SWAP_B1(uint8_t byte)
{
        return ((byte * 0x0802LU & 0x22110LU) |
                (byte * 0x8020LU & 0x88440LU)) * 0x10101LU >> 16;
}
 
static inline void gp_bit_swap_row_b1(uint8_t *row, unsigned int len)
{
        unsigned int i;
 
        for (i = 0; i < len; i++)
                row[i] = GP_BIT_SWAP_B1(row[i]);
}
 
static inline uint8_t GP_BIT_SWAP_B2(uint8_t byte)
{
        return ((byte & 0xC0) >> 6) | ((byte & 0x30) >> 2) |
               ((byte & 0x0C) << 2) | ((byte & 0x03) << 6);
}
 
static inline void gp_bit_swap_row_b2(uint8_t *row, unsigned int len)
{
        unsigned int i;
 
        for (i = 0; i < len; i++)
                row[i] = GP_BIT_SWAP_B2(row[i]);
}
 
static inline uint8_t GP_BIT_SWAP_B4(uint8_t byte)
{
        return ((byte & 0xf0) >> 4) | ((byte & 0x0f) << 4);
}
 
static inline void gp_bit_swap_row_b4(uint8_t *row, unsigned int len)
{
        unsigned int i;
 
        for (i = 0; i < len; i++)
                row[i] = GP_BIT_SWAP_B4(row[i]);
}
 
#endif /* CORE_GP_BIT_SWAP_H */