kernel/mem-mask.cx at main · overcq/kernel · GitHub

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//-*-C-*-
/*******************************************************************************
*   ___   publicplace
*  ¦OUX¦  C+
*  ¦/C+¦  OUX/C+ OS
*   ---   kernel
*         variable length mask
* ©overcq                on ‟Gentoo Linux 23.0” “x86_64”            2024‒11‒13 L
*******************************************************************************/
_export
Pc
E_mem_Q_mask_M( N length
){  N bytes = length / 8 + ( length % 8 ? 1 : 0 );
    Pc mask = M(bytes);
    if( !mask )
        return mask;
    _0( mask, bytes );
    return mask;
}
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_export
B
E_mem_Q_mask_R( Pc mask
, N bit
){  N byte = bit / 8;
    bit %= 8;
    return mask[byte] & ( 1 << bit );
}
_export
N
E_mem_Q_mask_R_first_clear( Pc mask
, N length
){  N bytes = length / 8 + ( length % 8 ? 1 : 0 );
    for( N byte_i = 0; byte_i != bytes - 1; byte_i++ )
        for( N bit_i = 0; bit_i != 8; bit_i++ )
            if( !( mask[ byte_i ] & ( 1 << bit_i )))
                return byte_i * 8 + bit_i;
    for( N bit_i = 0; bit_i != length; bit_i++ )
        if( !( mask[ bytes - 1 ] & ( 1 << bit_i )))
            return ( bytes - 1 ) * 8 + bit_i;
    return ~0;
}
//------------------------------------------------------------------------------
_export
void
E_mem_Q_mask_P_set( Pc mask
, N bit
){  N byte = bit / 8;
    bit %= 8;
    mask[byte] |= 1 << bit;
}
_export
void
E_mem_Q_mask_P_clear( Pc mask
, N bit
){  N byte = bit / 8;
    bit %= 8;
    mask[byte] &= ~( 1 << bit );
}
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_export
N
E_mem_Q_mask_I_resize( Pc *mask
, N length_old
, N length_new
){  N bytes_old = length_old / 8 + ( length_old % 8 ? 1 : 0 );
    N bytes_new = length_new / 8 + ( length_new % 8 ? 1 : 0 );
    if( bytes_old == bytes_new )
    {   N length_new_1 = length_new % 8 ? length_new % 8 : 8;
        if( length_old % 8 < length_new_1 )
            for( N bit_i = length_old % 8; bit_i != length_new_1; bit_i++ )
                (*mask)[ bytes_new - 1 ] &= ~( 1 << bit_i );
        return 0;
    }
    if( bytes_old < bytes_new )
    {   Pc p = E_mem_Q_blk_I_append( mask, bytes_new - bytes_old );
        Kp(p)
            return ~0;
        _0( p, bytes_new - bytes_old );
    }else
    {   Kp( E_mem_Q_blk_I_remove( mask, bytes_new, bytes_old - bytes_new ))
            return ~0;
    }
    return 0;
}
/******************************************************************************/