cosmetic changes

2019/include/bits.h

@@ -14,6 +14,7 @@
 #define BITS_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
 /* next include will define __WORDSIZE: 32 or 64
  */
@@ -262,7 +263,231 @@ static __always_inline int popcount32(u32 n)
 #   endif
 }
 
+/*  rolXX are taken from kernel's <linux/bitops.h> are are:
+ * SPDX-License-Identifier: GPL-2.0
+ */
 
+/**
+ * rol64 - rotate a 64-bit value left
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline u64 rol64(u64 word, unsigned int shift)
+{
+	return (word << (shift & 63)) | (word >> ((-shift) & 63));
+}
+
+/**
+ * ror64 - rotate a 64-bit value right
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline u64 ror64(u64 word, unsigned int shift)
+{
+	return (word >> (shift & 63)) | (word << ((-shift) & 63));
+}
+
+/**
+ * rol32 - rotate a 32-bit value left
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline u32 rol32(u32 word, unsigned int shift)
+{
+	return (word << (shift & 31)) | (word >> ((-shift) & 31));
+}
+
+/**
+ * ror32 - rotate a 32-bit value right
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline u32 ror32(u32 word, unsigned int shift)
+{
+	return (word >> (shift & 31)) | (word << ((-shift) & 31));
+}
+
+/**
+ * rol16 - rotate a 16-bit value left
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline u16 rol16(u16 word, unsigned int shift)
+{
+	return (word << (shift & 15)) | (word >> ((-shift) & 15));
+}
+
+/**
+ * ror16 - rotate a 16-bit value right
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline u16 ror16(u16 word, unsigned int shift)
+{
+	return (word >> (shift & 15)) | (word << ((-shift) & 15));
+}
+
+/**
+ * rol8 - rotate an 8-bit value left
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline u8 rol8(u8 word, unsigned int shift)
+{
+	return (word << (shift & 7)) | (word >> ((-shift) & 7));
+}
+
+/**
+ * ror8 - rotate an 8-bit value right
+ * @word: value to rotate
+ * @shift: bits to roll
+ */
+static inline u8 ror8(u8 word, unsigned int shift)
+{
+	return (word >> (shift & 7)) | (word << ((-shift) & 7));
+}
+
+/**
+ * ilog2 -
+ */
+static __always_inline __attribute__((const))
+int __ilog2_u32(u32 n)
+{
+	return fls32(n) - 1;
+}
+
+static __always_inline __attribute__((const))
+int __ilog2_u64(u64 n)
+{
+	return fls64(n) - 1;
+}
+
+/**
+ * is_power_of_2() - check if a value is a power of two
+ * @n: the value to check
+ *
+ * Determine whether some value is a power of two, where zero is
+ * *not* considered a power of two.
+ * Return: true if @n is a power of 2, otherwise false.
+ */
+static inline __attribute__((const))
+bool is_power_of_2(unsigned long n)
+{
+	return (n != 0 && ((n & (n - 1)) == 0));
+}
+
+/**
+ * ilog2 - log base 2 of 32-bit or a 64-bit unsigned value
+ * @n: parameter
+ *
+ * constant-capable log of base 2 calculation
+ * - this can be used to initialise global variables from constant data, hence
+ * the massive ternary operator construction
+ *
+ * selects the appropriately-sized optimised version depending on sizeof(n)
+ */
+#define ilog2(n) \
+( \
+	__builtin_constant_p(n) ?	\
+	((n) < 2 ? 0 :			\
+	 63 - __builtin_clzll(n)) :	\
+	(sizeof(n) <= 4) ?		\
+	__ilog2_u32(n) :		\
+	__ilog2_u64(n)			\
+ )
+
+/**
+ * roundup_pow_of_two - round the given value up to nearest power of two
+ * @n: parameter
+ *
+ * round the given value up to the nearest power of two
+ * - the result is undefined when n == 0
+ * - this can be used to initialise global variables from constant data
+ */
+#define roundup_pow_of_two(n)			\
+(						\
+	__builtin_constant_p(n) ? (		\
+		((n) == 1) ? 1 :		\
+		(1UL << (ilog2((n) - 1) + 1))	\
+				   ) :		\
+	__roundup_pow_of_two(n)			\
+ )
+
+/**
+ * rounddown_pow_of_two - round the given value down to nearest power of two
+ * @n: parameter
+ *
+ * round the given value down to the nearest power of two
+ * - the result is undefined when n == 0
+ * - this can be used to initialise global variables from constant data
+ */
+#define rounddown_pow_of_two(n)			\
+(						\
+	__builtin_constant_p(n) ? (		\
+		(1UL << ilog2(n))) :		\
+	__rounddown_pow_of_two(n)		\
+ )
+
+static inline __attribute_const__
+int __order_base_2(unsigned long n)
+{
+	return n > 1 ? ilog2(n - 1) + 1 : 0;
+}
+
+/**
+ * order_base_2 - calculate the (rounded up) base 2 order of the argument
+ * @n: parameter
+ *
+ * The first few values calculated by this routine:
+ *  ob2(0) = 0
+ *  ob2(1) = 0
+ *  ob2(2) = 1
+ *  ob2(3) = 2
+ *  ob2(4) = 2
+ *  ob2(5) = 3
+ *  ... and so on.
+ */
+#define order_base_2(n)				\
+(						\
+	__builtin_constant_p(n) ? (		\
+		((n) == 0 || (n) == 1) ? 0 :	\
+		ilog2((n) - 1) + 1) :		\
+	__order_base_2(n)			\
+)
+
+static inline __attribute__((const))
+int __bits_per(unsigned long n)
+{
+	if (n < 2)
+		return 1;
+	if (is_power_of_2(n))
+		return order_base_2(n) + 1;
+	return order_base_2(n);
+}
+
+/**
+ * bits_per - calculate the number of bits required for the argument
+ * @n: parameter
+ *
+ * This is constant-capable and can be used for compile time
+ * initializations, e.g bitfields.
+ *
+ * The first few values calculated by this routine:
+ * bf(0) = 1
+ * bf(1) = 1
+ * bf(2) = 2
+ * bf(3) = 2
+ * bf(4) = 3
+ * ... and so on.
+ */
+#define bits_per(n)				\
+(						\
+	__builtin_constant_p(n) ? (		\
+		((n) == 0 || (n) == 1)		\
+			? 1 : ilog2(n) + 1	\
+	) :					\
+	__bits_per(n)				\
+)
 
 /** bit_for_each - iterate over an u64/u32 bits
  * @pos:        an int used as current bit

2019/include/br.h

@@ -30,7 +30,6 @@
 #define ___PASTE(x, y)      x##y
 #define __PASTE(x, y)       ___PASTE(x, y)
 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-//__##prefix##__COUNTER__
 
 /* see https://lkml.org/lkml/2018/3/20/845 for explanation of this monster
  */
@@ -70,6 +69,8 @@
 		__cmp(x, y, op), \
 		__cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
 
+#define __pure   __attribute__((__pure__))
+
 /**
  * min - return minimum of two values of the same or compatible types
  * @x: first value

2019/include/bug.h

@@ -8,7 +8,8 @@
 #include "likely.h"
 #include "debug.h"
 
-/* inspired by Linux kernel's <asm/bug.h> */
+/* BUG functions inspired by Linux kernel's <asm/bug.h>
+ */
 
 #define panic() exit(0xff)
 

2019/include/hash.h

@@ -2,7 +2,7 @@
 
 #ifndef _BR_HASH_H
 #define _BR_HASH_H
-/* adaptation of Linux kernel's <linux/hash.h>
+/* adaptation of Linux kernel's <linux/hash.h> and <linux/stringhash.h>
  */
 
 /* Fast hashing routine for ints,  longs and pointers.
@@ -11,6 +11,8 @@
 #include <asm/types.h>
 #include <asm/bitsperlong.h>
 #include "bits.h"
+#include "br.h"
+
 /*
  * The "GOLDEN_RATIO_PRIME" is used in ifs/btrfs/brtfs_inode.h and
  * fs/inode.c.  It's not actually prime any more (the previous primes
@@ -98,4 +100,74 @@ static inline u32 hash32_ptr(const void *ptr)
 	return (u32)val;
 }
 
+/*
+ * Routines for hashing strings of bytes to a 32-bit hash value.
+ *
+ * These hash functions are NOT GUARANTEED STABLE between kernel
+ * versions, architectures, or even repeated boots of the same kernel.
+ * (E.g. they may depend on boot-time hardware detection or be
+ * deliberately randomized.)
+ *
+ * They are also not intended to be secure against collisions caused by
+ * malicious inputs; much slower hash functions are required for that.
+ *
+ * They are optimized for pathname components, meaning short strings.
+ * Even if a majority of files have longer names, the dynamic profile of
+ * pathname components skews short due to short directory names.
+ * (E.g. /usr/lib/libsesquipedalianism.so.3.141.)
+ */
+
+/*
+ * Version 1: one byte at a time.  Example of use:
+ *
+ * unsigned long hash = init_name_hash;
+ * while (*p)
+ *	hash = partial_name_hash(tolower(*p++), hash);
+ * hash = end_name_hash(hash);
+ *
+ * Although this is designed for bytes, fs/hfsplus/unicode.c
+ * abuses it to hash 16-bit values.
+ */
+
+/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
+#define init_name_hash(salt)		(unsigned long)(salt)
+
+/* partial hash update function. Assume roughly 4 bits per character */
+static inline unsigned long
+partial_name_hash(unsigned long c, unsigned long prevhash)
+{
+	return (prevhash + (c << 4) + (c >> 4)) * 11;
+}
+
+/*
+ * Finally: cut down the number of bits to a int value (and try to avoid
+ * losing bits).  This also has the property (wanted by the dcache)
+ * that the msbits make a good hash table index.
+ */
+static inline unsigned int end_name_hash(unsigned long hash)
+{
+	return hash_long(hash, 32);
+}
+
+/*
+ * Version 2: One word (32 or 64 bits) at a time.
+ * If CONFIG_DCACHE_WORD_ACCESS is defined (meaning <asm/word-at-a-time.h>
+ * exists, which describes major Linux platforms like x86 and ARM), then
+ * this computes a different hash function much faster.
+ *
+ * If not set, this falls back to a wrapper around the preceding.
+ */
+extern unsigned int __pure hash_string(const void *salt, const char *, unsigned int);
+
+/*
+ * A hash_len is a u64 with the hash of a string in the low
+ * half and the length in the high half.
+ */
+#define hashlen_hash(hashlen) ((u32)(hashlen))
+#define hashlen_len(hashlen)  ((u32)((hashlen) >> 32))
+#define hashlen_create(hash, len) ((u64)(len)<<32 | (u32)(hash))
+
+/* Return the "hash_len" (hash and length) of a null-terminated string */
+extern u64 __pure hashlen_string(const void *salt, const char *name);
+
 #endif /* _BR_HASH_H */