Commit 9dad92b9 authored by Ivo van Doorn's avatar Ivo van Doorn Committed by John W. Linville
Browse files

rt2x00: Calculate register offset during compile time



By using __ffs() the register offsets were always calculated
at run-time which all FIELD32/FIELD16 definitions were builtin
constants. This means we can heavily optimize the register handling
by allowing GCC to do all the work during compilation.

Add some compile_ffs() macros to perform the calculation at
compile time. After this each rt2x00 module size is reduced
by ~2500 bytes. And the stack size of several functions is reduced
as well which further limits the number of rt2x00 results in
'make checkstack'.

v2: Merge GertJan's bugfix of patch [1/11] directly into this patch
      instead of providing it as seperate patch.
v3: Add extra parentheses when bitshifting __x
Signed-off-by: default avatarGertjan van Wingerde <gwingerde@kpnplanet.nl>
Signed-off-by: default avatarIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 030352a9
......@@ -130,40 +130,71 @@ struct rt2x00_field32 {
/*
* Power of two check, this will check
* if the mask that has been given contains
* and contiguous set of bits.
* if the mask that has been given contains and contiguous set of bits.
* Note that we cannot use the is_power_of_2() function since this
* check must be done at compile-time.
*/
#define is_power_of_two(x) ( !((x) & ((x)-1)) )
#define low_bit_mask(x) ( ((x)-1) & ~(x) )
#define is_valid_mask(x) is_power_of_two(1 + (x) + low_bit_mask(x))
/*
* Macro's to find first set bit in a variable.
* These macro's behaves the same as the __ffs() function with
* the most important difference that this is done during
* compile-time rather then run-time.
*/
#define compile_ffs2(__x) \
( ((__x) & 0x1) ? 0 : 1 )
#define compile_ffs4(__x) \
( ((__x) & 0x3) ? \
compile_ffs2(__x) : (compile_ffs2((__x) >> 2) + 2) )
#define compile_ffs8(__x) \
( ((__x) & 0xf) ? \
compile_ffs4(__x) : (compile_ffs4((__x) >> 4) + 4) )
#define compile_ffs16(__x) \
( ((__x) & 0xff) ? \
compile_ffs8(__x) : (compile_ffs8((__x) >> 8) + 8) )
#define compile_ffs32(__x) \
( ((__x) & 0xffff) ? \
compile_ffs16(__x) : (compile_ffs16((__x) >> 16) + 16) )
/*
* This macro will check the requirements for the FIELD{8,16,32} macros
* The mask should be a constant non-zero contiguous set of bits which
* does not exceed the given typelimit.
*/
#define FIELD_CHECK(__mask, __type) \
BUILD_BUG_ON(!__builtin_constant_p(__mask) || \
!(__mask) || \
!is_valid_mask(__mask) || \
(__mask) != (__type)(__mask)) \
#define FIELD8(__mask) \
({ \
BUILD_BUG_ON(!(__mask) || \
!is_valid_mask(__mask) || \
(__mask) != (u8)(__mask)); \
FIELD_CHECK(__mask, u8); \
(struct rt2x00_field8) { \
__ffs(__mask), (__mask) \
compile_ffs8(__mask), (__mask) \
}; \
})
#define FIELD16(__mask) \
({ \
BUILD_BUG_ON(!(__mask) || \
!is_valid_mask(__mask) || \
(__mask) != (u16)(__mask));\
FIELD_CHECK(__mask, u16); \
(struct rt2x00_field16) { \
__ffs(__mask), (__mask) \
compile_ffs16(__mask), (__mask) \
}; \
})
#define FIELD32(__mask) \
({ \
BUILD_BUG_ON(!(__mask) || \
!is_valid_mask(__mask) || \
(__mask) != (u32)(__mask));\
FIELD_CHECK(__mask, u32); \
(struct rt2x00_field32) { \
__ffs(__mask), (__mask) \
compile_ffs32(__mask), (__mask) \
}; \
})
......
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