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Diffstat (limited to 'include/drm/intel/pick.h')
| -rw-r--r-- | include/drm/intel/pick.h | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/include/drm/intel/pick.h b/include/drm/intel/pick.h new file mode 100644 index 000000000000..d976fab8f270 --- /dev/null +++ b/include/drm/intel/pick.h @@ -0,0 +1,51 @@ +/* SPDX-License-Identifier: MIT */ +/* Copyright © 2026 Intel Corporation */ + +#ifndef _PICK_H_ +#define _PICK_H_ + +/* + * Given the first two numbers __a and __b of arbitrarily many evenly spaced + * numbers, pick the 0-based __index'th value. + * + * Always prefer this over _PICK() if the numbers are evenly spaced. + */ +#define _PICK_EVEN(__index, __a, __b) ((__a) + (__index) * ((__b) - (__a))) + +/* + * Like _PICK_EVEN(), but supports 2 ranges of evenly spaced address offsets. + * @__c_index corresponds to the index in which the second range starts to be + * used. Using math interval notation, the first range is used for indexes [ 0, + * @__c_index), while the second range is used for [ @__c_index, ... ). Example: + * + * #define _FOO_A 0xf000 + * #define _FOO_B 0xf004 + * #define _FOO_C 0xf008 + * #define _SUPER_FOO_A 0xa000 + * #define _SUPER_FOO_B 0xa100 + * #define FOO(x) _MMIO(_PICK_EVEN_2RANGES(x, 3, \ + * _FOO_A, _FOO_B, \ + * _SUPER_FOO_A, _SUPER_FOO_B)) + * + * This expands to: + * 0: 0xf000, + * 1: 0xf004, + * 2: 0xf008, + * 3: 0xa000, + * 4: 0xa100, + * 5: 0xa200, + * ... + */ +#define _PICK_EVEN_2RANGES(__index, __c_index, __a, __b, __c, __d) \ + (BUILD_BUG_ON_ZERO(!__is_constexpr(__c_index)) + \ + ((__index) < (__c_index) ? _PICK_EVEN(__index, __a, __b) : \ + _PICK_EVEN((__index) - (__c_index), __c, __d))) + +/* + * Given the arbitrary numbers in varargs, pick the 0-based __index'th number. + * + * Always prefer _PICK_EVEN() over this if the numbers are evenly spaced. + */ +#define _PICK(__index, ...) (((const u32 []){ __VA_ARGS__ })[__index]) + +#endif |