mirror of
https://source.denx.de/u-boot/u-boot.git
synced 2025-10-31 08:21:36 +01:00
8756de2824
These new operations allow manipulation of bitfields within a word by using a mask instead of width and shift values to extract/replace the bitfields. Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@freescale.com> Acked-by: Joe Hershberger <joe.hershberger@ni.com> Reviewed-by: York Sun <yorksun@freescale.com>
91 lines
2.5 KiB
C
91 lines
2.5 KiB
C
/*
|
|
* Copyright 2013 Broadcom Corporation.
|
|
*
|
|
* SPDX-License-Identifier: GPL-2.0+
|
|
*/
|
|
|
|
/*
|
|
* Bitfield operations
|
|
*
|
|
* These are generic bitfield operations which allow manipulation of variable
|
|
* width bitfields within a word. One use of this would be to use data tables
|
|
* to determine how to reprogram fields within R/W hardware registers.
|
|
*
|
|
* Example:
|
|
*
|
|
* old_reg_val
|
|
* +--------+----+---+--+-----+----------+
|
|
* | | | | | old | |
|
|
* +--------+----+---+--+-----+----------+
|
|
*
|
|
* new_reg_val
|
|
* +--------+----+---+--+-----+----------+
|
|
* | | | | | new | |
|
|
* +--------+----+---+--+-----+----------+
|
|
*
|
|
* mask = bitfield_mask(10, 5);
|
|
* old = bitfield_extract(old_reg_val, 10, 5);
|
|
* new_reg_val = bitfield_replace(old_reg_val, 10, 5, new);
|
|
*
|
|
* or
|
|
*
|
|
* mask = bitfield_mask(10, 5);
|
|
* old = bitfield_extract_by_mask(old_reg_val, mask);
|
|
* new_reg_val = bitfield_replace_by_mask(old_reg_val, mask, new);
|
|
*
|
|
* The numbers 10 and 5 could for example come from data
|
|
* tables which describe all bitfields in all registers.
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
|
|
/* Produces a mask of set bits covering a range of a uint value */
|
|
static inline uint bitfield_mask(uint shift, uint width)
|
|
{
|
|
return ((1 << width) - 1) << shift;
|
|
}
|
|
|
|
/* Extract the value of a bitfield found within a given register value */
|
|
static inline uint bitfield_extract(uint reg_val, uint shift, uint width)
|
|
{
|
|
return (reg_val & bitfield_mask(shift, width)) >> shift;
|
|
}
|
|
|
|
/*
|
|
* Replace the value of a bitfield found within a given register value
|
|
* Returns the newly modified uint value with the replaced field.
|
|
*/
|
|
static inline uint bitfield_replace(uint reg_val, uint shift, uint width,
|
|
uint bitfield_val)
|
|
{
|
|
uint mask = bitfield_mask(shift, width);
|
|
|
|
return (reg_val & ~mask) | ((bitfield_val << shift) & mask);
|
|
}
|
|
|
|
/* Produces a shift of the bitfield given a mask */
|
|
static inline uint bitfield_shift(uint mask)
|
|
{
|
|
return mask ? ffs(mask) - 1 : 0;
|
|
}
|
|
|
|
/* Extract the value of a bitfield found within a given register value */
|
|
static inline uint bitfield_extract_by_mask(uint reg_val, uint mask)
|
|
{
|
|
uint shift = bitfield_shift(mask);
|
|
|
|
return (reg_val & mask) >> shift;
|
|
}
|
|
|
|
/*
|
|
* Replace the value of a bitfield found within a given register value
|
|
* Returns the newly modified uint value with the replaced field.
|
|
*/
|
|
static inline uint bitfield_replace_by_mask(uint reg_val, uint mask,
|
|
uint bitfield_val)
|
|
{
|
|
uint shift = bitfield_shift(mask);
|
|
|
|
return (reg_val & ~mask) | ((bitfield_val << shift) & mask);
|
|
}
|