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include/bitfield: Add new bitfield operations 

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>
utp
Codrin Ciubotariu 2015-07-24 16:55:25 +03:00 committed by York Sun
parent 440873dfc4
commit 8756de2824
1 changed files with 32 additions and 0 deletions
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32
include/bitfield.h
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@ -27,6 +27,12 @@
* 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.
*/
@ -56,3 +62,29 @@ static inline uint bitfield_replace(uint reg_val, uint shift, uint 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);
}