bitops.h

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#ifndef _GPXE_BITOPS_H
#define _GPXE_BITOPS_H

/*
 * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

FILE_LICENCE ( GPL2_OR_LATER );

/**
 * @file
 *
 * Bit operations
 *
 */

#include <stdint.h>
#include <byteswap.h>

/* Endianness selection.
 *
 * This is a property of the NIC, not a property of the host CPU.
 */
#ifdef BITOPS_LITTLE_ENDIAN
#define cpu_to_BIT64    cpu_to_le64
#define cpu_to_BIT32    cpu_to_le32
#define BIT64_to_cpu    le64_to_cpu
#define BIT32_to_cpu    le32_to_cpu
#endif
#ifdef BITOPS_BIG_ENDIAN
#define cpu_to_BIT64    cpu_to_be64
#define cpu_to_BIT32    cpu_to_be32
#define BIT64_to_cpu    be64_to_cpu
#define BIT32_to_cpu    be32_to_cpu
#endif

/** Datatype used to represent a bit in the pseudo-structures */
typedef unsigned char pseudo_bit_t;

/**
 * Wrapper structure for pseudo_bit_t structures
 *
 * This structure provides a wrapper around pseudo_bit_t structures.
 * It has the correct size, and also encapsulates type information
 * about the underlying pseudo_bit_t-based structure, which allows the
 * BIT_FILL() etc. macros to work without requiring explicit type
 * information.
 */
#define PSEUDO_BIT_STRUCT( _structure )                                       \
        union {                                                               \
                uint8_t bytes[ sizeof ( _structure ) / 8 ];                   \
                uint32_t dwords[ sizeof ( _structure ) / 32 ];                \
                uint64_t qwords[ sizeof ( _structure ) / 64 ];                \
                _structure *dummy[0];                                         \
        } u

/** Get pseudo_bit_t structure type from wrapper structure pointer */
#define PSEUDO_BIT_STRUCT_TYPE( _ptr )                                        \
        typeof ( *((_ptr)->u.dummy[0]) )

/** Bit offset of a field within a pseudo_bit_t structure */
#define BIT_OFFSET( _ptr, _field )                                            \
        offsetof ( PSEUDO_BIT_STRUCT_TYPE ( _ptr ), _field )

/** Bit width of a field within a pseudo_bit_t structure */
#define BIT_WIDTH( _ptr, _field )                                             \
        sizeof ( ( ( PSEUDO_BIT_STRUCT_TYPE ( _ptr ) * ) NULL )->_field )

/** Qword offset of a field within a pseudo_bit_t structure */
#define QWORD_OFFSET( _ptr, _field )                                          \
        ( BIT_OFFSET ( _ptr, _field ) / 64 )

/** Qword bit offset of a field within a pseudo_bit_t structure */
#define QWORD_BIT_OFFSET( _ptr, _index, _field )                              \
        ( BIT_OFFSET ( _ptr, _field ) - ( 64 * (_index) ) )

/** Bit mask for a field within a pseudo_bit_t structure */
#define BIT_MASK( _ptr, _field )                                              \
        ( ( ~( ( uint64_t ) 0 ) ) >>                                          \
          ( 64 - BIT_WIDTH ( _ptr, _field ) ) )

/*
 * Assemble native-endian qword from named fields and values
 *
 */

#define BIT_ASSEMBLE_1( _ptr, _index, _field, _value )                        \
        ( ( ( uint64_t) (_value) ) <<                                         \
          QWORD_BIT_OFFSET ( _ptr, _index, _field ) )

#define BIT_ASSEMBLE_2( _ptr, _index, _field, _value, ... )                   \
        ( BIT_ASSEMBLE_1 ( _ptr, _index, _field, _value ) |                   \
          BIT_ASSEMBLE_1 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_ASSEMBLE_3( _ptr, _index, _field, _value, ... )                   \
        ( BIT_ASSEMBLE_1 ( _ptr, _index, _field, _value ) |                   \
          BIT_ASSEMBLE_2 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_ASSEMBLE_4( _ptr, _index, _field, _value, ... )                   \
        ( BIT_ASSEMBLE_1 ( _ptr, _index, _field, _value ) |                   \
          BIT_ASSEMBLE_3 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_ASSEMBLE_5( _ptr, _index, _field, _value, ... )                   \
        ( BIT_ASSEMBLE_1 ( _ptr, _index, _field, _value ) |                   \
          BIT_ASSEMBLE_4 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_ASSEMBLE_6( _ptr, _index, _field, _value, ... )                   \
        ( BIT_ASSEMBLE_1 ( _ptr, _index, _field, _value ) |                   \
          BIT_ASSEMBLE_5 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_ASSEMBLE_7( _ptr, _index, _field, _value, ... )                   \
        ( BIT_ASSEMBLE_1 ( _ptr, _index, _field, _value ) |                   \
          BIT_ASSEMBLE_6 ( _ptr, _index, __VA_ARGS__ ) )

/*
 * Build native-endian (positive) qword bitmasks from named fields
 *
 */

#define BIT_MASK_1( _ptr, _index, _field )                                    \
        ( BIT_MASK ( _ptr, _field ) <<                                        \
          QWORD_BIT_OFFSET ( _ptr, _index, _field ) )

#define BIT_MASK_2( _ptr, _index, _field, ... )                               \
        ( BIT_MASK_1 ( _ptr, _index, _field ) |                               \
          BIT_MASK_1 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_MASK_3( _ptr, _index, _field, ... )                               \
        ( BIT_MASK_1 ( _ptr, _index, _field ) |                               \
          BIT_MASK_2 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_MASK_4( _ptr, _index, _field, ... )                               \
        ( BIT_MASK_1 ( _ptr, _index, _field ) |                               \
          BIT_MASK_3 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_MASK_5( _ptr, _index, _field, ... )                               \
        ( BIT_MASK_1 ( _ptr, _index, _field ) |                               \
          BIT_MASK_4 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_MASK_6( _ptr, _index, _field, ... )                               \
        ( BIT_MASK_1 ( _ptr, _index, _field ) |                               \
          BIT_MASK_5 ( _ptr, _index, __VA_ARGS__ ) )

#define BIT_MASK_7( _ptr, _index, _field, ... )                               \
        ( BIT_MASK_1 ( _ptr, _index, _field ) |                               \
          BIT_MASK_6 ( _ptr, _index, __VA_ARGS__ ) )

/*
 * Populate little-endian qwords from named fields and values
 *
 */

#define BIT_FILL( _ptr, _index, _assembled ) do {                             \
                uint64_t *__ptr = &(_ptr)->u.qwords[(_index)];                \
                uint64_t __assembled = (_assembled);                          \
                *__ptr = cpu_to_BIT64 ( __assembled );                        \
        } while ( 0 )

#define BIT_FILL_1( _ptr, _field1, ... )                                      \
        BIT_FILL ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),                      \
                   BIT_ASSEMBLE_1 ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),     \
                                    _field1, __VA_ARGS__ ) )

#define BIT_FILL_2( _ptr, _field1, ... )                                      \
        BIT_FILL ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),                      \
                   BIT_ASSEMBLE_2 ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),     \
                                    _field1, __VA_ARGS__ ) )

#define BIT_FILL_3( _ptr, _field1, ... )                                      \
        BIT_FILL ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),                      \
                   BIT_ASSEMBLE_3 ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),     \
                                    _field1, __VA_ARGS__ ) )

#define BIT_FILL_4( _ptr, _field1, ... )                                      \
        BIT_FILL ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),                      \
                   BIT_ASSEMBLE_4 ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),     \
                                    _field1, __VA_ARGS__ ) )

#define BIT_FILL_5( _ptr, _field1, ... )                                      \
        BIT_FILL ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),                      \
                   BIT_ASSEMBLE_5 ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),     \
                                    _field1, __VA_ARGS__ ) )

#define BIT_FILL_6( _ptr, _field1, ... )                                      \
        BIT_FILL ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),                      \
                   BIT_ASSEMBLE_6 ( _ptr, QWORD_OFFSET ( _ptr, _field1 ),     \
                                    _field1, __VA_ARGS__ ) )

/** Extract value of named field */
#define BIT_GET64( _ptr, _field )                                             \
        ( {                                                                   \
                unsigned int __index = QWORD_OFFSET ( _ptr, _field );         \
                uint64_t *__ptr = &(_ptr)->u.qwords[__index];                 \
                uint64_t __value = BIT64_to_cpu ( *__ptr );                   \
                __value >>=                                                   \
                    QWORD_BIT_OFFSET ( _ptr, __index, _field );               \
                __value &= BIT_MASK ( _ptr, _field );                         \
                __value;                                                      \
        } )

/** Extract value of named field (for fields up to the size of a long) */
#define BIT_GET( _ptr, _field )                                               \
        ( ( unsigned long ) BIT_GET64 ( _ptr, _field ) )

#define BIT_SET( _ptr, _field, _value ) do {                                  \
                unsigned int __index = QWORD_OFFSET ( _ptr, _field );         \
                uint64_t *__ptr = &(_ptr)->u.qwords[__index];                 \
                unsigned int __shift =                                        \
                        QWORD_BIT_OFFSET ( _ptr, __index, _field );           \
                uint64_t __value = (_value);                                  \
                *__ptr &= cpu_to_BIT64 ( ~( BIT_MASK ( _ptr, _field ) <<      \
                                            __shift ) );                      \
                *__ptr |= cpu_to_BIT64 ( __value << __shift );                \
        } while ( 0 )

#endif /* _GPXE_BITOPS_H */