13 /* Compute a */
14 #define log2_to_int_t(type, a_lg2) ((type)(((type)1) << (a_lg2)))
15 static_assert(log2_to_int_t(unsigned int, 0) == 1);
17 /* Compute a - 1 (aka all low bits set) */
18 #define log2_to_max_int_t(type, a_lg2) ((type)(log2_to_int_t(type, a_lg2) - 1))
20 /* Compute a / b */
21 #define log2_div_t(type, a, b_lg2) ((type)(((type)a) >> (b_lg2)))  argument
22 static_assert(log2_div_t(unsigned int, 4, 2) == 1);
26  *   a / c == b / c
29 #define log2_div_eq_t(type, a, b, c_lg2) \  argument
30 	(log2_div_t(type, (a) ^ (b), c_lg2) == 0)
31 static_assert(log2_div_eq_t(unsigned int, 1, 1, 2));
33 /* Compute a % b */
34 #define log2_mod_t(type, a, b_lg2) \  argument
35 	((type)(((type)a) & log2_to_max_int_t(type, b_lg2)))
36 static_assert(log2_mod_t(unsigned int, 1, 2) == 1);
40  *   a % b == b - 1
41  * aka the low bits are all 1s
43 #define log2_mod_eq_max_t(type, a, b_lg2) \  argument
44 	(log2_mod_t(type, a, b_lg2) == log2_to_max_int_t(type, b_lg2))
48  * Return a value such that:
49  *    a / b == ret / b
53 #define log2_set_mod_t(type, a, val, b_lg2) \  argument
54 	((((type)(a)) & (~log2_to_max_int_t(type, b_lg2))) | ((type)(val)))
55 static_assert(log2_set_mod_t(unsigned int, 3, 1, 2) == 1);
57 /* Return a value such that:
58  *    a / b == ret / b
59  *    ret % b == b - 1
60  * aka set the low bits to all 1s
62 #define log2_set_mod_max_t(type, a, b_lg2) \  argument
63 	(((type)(a)) | log2_to_max_int_t(type, b_lg2))
66 /* Compute a * b */
67 #define log2_mul_t(type, a, b_lg2) ((type)(((type)a) << (b_lg2)))  argument
70 #define _dispatch_sz(type, fn, a) \  argument
71 	(sizeof(type) == 4 ? fn##32((u32)a) : fn##64(a))
76  *    fls_t(u3, 1) == 1
77  *    a >= log2_to_int(ret - 1)
80 static inline unsigned int fls32(u32 a)  in fls32()  argument
82 	return fls(a);  in fls32()
84 #define fls_t(type, a) _dispatch_sz(type, fls, a)  argument
89  *    ffs_t(u32, 1) == 0
90  *    log_mod(a, ret) == 0
93 static inline unsigned int __ffs32(u32 a)  in __ffs32()  argument
95 	return __ffs(a);  in __ffs32()
97 #define ffs_t(type, a) _dispatch_sz(type, __ffs, a)  argument
103  *    ffz_t(u32, 1) == 1
104  *    log_mod(a, ret) == log_to_max_int(ret)
107 static inline unsigned int ffz32(u32 a)  in ffz32()  argument
109 	return ffz(a);  in ffz32()
111 static inline unsigned int ffz64(u64 a)  in ffz64()  argument
114 		return ffz(a);  in ffz64()
116 	if ((u32)a == U32_MAX)  in ffz64()
117 		return ffz32(a >> 32) + 32;  in ffz64()
118 	return ffz32(a);  in ffz64()
120 #define ffz_t(type, a) _dispatch_sz(type, ffz, a)  argument