2 files changed, 89 insertions, 214 deletions

diff --git a/lib/find_last_bit.c b/lib/find_last_bit.c
index 91ca09fbf6f9..3e3be40c6a6e 100644
--- a/lib/find_last_bit.c
+++ b/lib/find_last_bit.c
@@ -4,6 +4,9 @@
  * Written by Rusty Russell <rusty@rustcorp.com.au>
  * (Inspired by David Howell's find_next_bit implementation)
  *
+ * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
+ * size and improve performance, 2015.
+ *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
@@ -11,37 +14,26 @@
  */
 
 #include <linux/bitops.h>
+#include <linux/bitmap.h>
 #include <linux/export.h>
-#include <asm/types.h>
-#include <asm/byteorder.h>
+#include <linux/kernel.h>
 
 #ifndef find_last_bit
 
 unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
 {
-        unsigned long words;
-        unsigned long tmp;
-
-        /* Start at final word. */
-        words = size / BITS_PER_LONG;
+        if (size) {
+                unsigned long val = BITMAP_LAST_WORD_MASK(size);
+                unsigned long idx = (size-1) / BITS_PER_LONG;
 
-        /* Partial final word? */
-        if (size & (BITS_PER_LONG-1)) {
-                tmp = (addr[words] & (~0UL >> (BITS_PER_LONG
-                                         - (size & (BITS_PER_LONG-1)))));
-                if (tmp)
-                        goto found;
-        }
+                do {
+                        val &= addr[idx];
+                        if (val)
+                                return idx * BITS_PER_LONG + __fls(val);
 
-        while (words) {
-                tmp = addr[--words];
-                if (tmp) {
-found:
-                        return words * BITS_PER_LONG + __fls(tmp);
-                }
+                        val = ~0ul;
+                } while (idx--);
         }
-
-        /* Not found */
         return size;
 }
 EXPORT_SYMBOL(find_last_bit);
diff --git a/lib/find_next_bit.c b/lib/find_next_bit.c
index 0cbfc0b4398f..cbea5ef843aa 100644
--- a/lib/find_next_bit.c
+++ b/lib/find_next_bit.c
@@ -3,6 +3,9 @@
  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
+ * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
+ * size and improve performance, 2015.
+ *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
@@ -11,98 +14,58 @@
 
 #include <linux/bitops.h>
 #include <linux/export.h>
-#include <asm/types.h>
-#include <asm/byteorder.h>
+#include <linux/kernel.h>
 
-#define BITOP_WORD(nr)          ((nr) / BITS_PER_LONG)
+#if !defined(find_next_bit) || !defined(find_next_zero_bit)
 
-#ifndef find_next_bit
 /*
- * Find the next set bit in a memory region.
+ * This is a common helper function for find_next_bit and
+ * find_next_zero_bit.  The difference is the "invert" argument, which
+ * is XORed with each fetched word before searching it for one bits.
  */
-unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
-                            unsigned long offset)
+static unsigned long _find_next_bit(const unsigned long *addr,
+                unsigned long nbits, unsigned long start, unsigned long invert)
 {
-        const unsigned long *p = addr + BITOP_WORD(offset);
-        unsigned long result = offset & ~(BITS_PER_LONG-1);
         unsigned long tmp;
 
-        if (offset >= size)
-                return size;
-        size -= result;
-        offset %= BITS_PER_LONG;
-        if (offset) {
-                tmp = *(p++);
-                tmp &= (~0UL << offset);
-                if (size < BITS_PER_LONG)
-                        goto found_first;
-                if (tmp)
-                        goto found_middle;
-                size -= BITS_PER_LONG;
-                result += BITS_PER_LONG;
-        }
-        while (size & ~(BITS_PER_LONG-1)) {
-                if ((tmp = *(p++)))
-                        goto found_middle;
-                result += BITS_PER_LONG;
-                size -= BITS_PER_LONG;
+        if (!nbits || start >= nbits)
+                return nbits;
+
+        tmp = addr[start / BITS_PER_LONG] ^ invert;
+
+        /* Handle 1st word. */
+        tmp &= BITMAP_FIRST_WORD_MASK(start);
+        start = round_down(start, BITS_PER_LONG);
+
+        while (!tmp) {
+                start += BITS_PER_LONG;
+                if (start >= nbits)
+                        return nbits;
+
+                tmp = addr[start / BITS_PER_LONG] ^ invert;
         }
-        if (!size)
-                return result;
-        tmp = *p;
 
-found_first:
-        tmp &= (~0UL >> (BITS_PER_LONG - size));
-        if (tmp == 0UL)         /* Are any bits set? */
-                return result + size;   /* Nope. */
-found_middle:
-        return result + __ffs(tmp);
+        return min(start + __ffs(tmp), nbits);
 }
-EXPORT_SYMBOL(find_next_bit);
 #endif
 
-#ifndef find_next_zero_bit
+#ifndef find_next_bit
 /*
- * This implementation of find_{first,next}_zero_bit was stolen from
- * Linus' asm-alpha/bitops.h.
+ * Find the next set bit in a memory region.
  */
+unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
+                            unsigned long offset)
+{
+        return _find_next_bit(addr, size, offset, 0UL);
+}
+EXPORT_SYMBOL(find_next_bit);
+#endif
+
+#ifndef find_next_zero_bit
 unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
                                  unsigned long offset)
 {
-        const unsigned long *p = addr + BITOP_WORD(offset);
-        unsigned long result = offset & ~(BITS_PER_LONG-1);
-        unsigned long tmp;
-
-        if (offset >= size)
-                return size;
-        size -= result;
-        offset %= BITS_PER_LONG;
-        if (offset) {
-                tmp = *(p++);
-                tmp |= ~0UL >> (BITS_PER_LONG - offset);
-                if (size < BITS_PER_LONG)
-                        goto found_first;
-                if (~tmp)
-                        goto found_middle;
-                size -= BITS_PER_LONG;
-                result += BITS_PER_LONG;
-        }
-        while (size & ~(BITS_PER_LONG-1)) {
-                if (~(tmp = *(p++)))
-                        goto found_middle;
-                result += BITS_PER_LONG;
-                size -= BITS_PER_LONG;
-        }
-        if (!size)
-                return result;
-        tmp = *p;
-
-found_first:
-        tmp |= ~0UL << size;
-        if (tmp == ~0UL)        /* Are any bits zero? */
-                return result + size;   /* Nope. */
-found_middle:
-        return result + ffz(tmp);
+        return _find_next_bit(addr, size, offset, ~0UL);
 }
 EXPORT_SYMBOL(find_next_zero_bit);
 #endif
@@ -113,24 +76,14 @@ EXPORT_SYMBOL(find_next_zero_bit);
  */
 unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
 {
-        const unsigned long *p = addr;
-        unsigned long result = 0;
-        unsigned long tmp;
+        unsigned long idx;
 
-        while (size & ~(BITS_PER_LONG-1)) {
-                if ((tmp = *(p++)))
-                        goto found;
-                result += BITS_PER_LONG;
-                size -= BITS_PER_LONG;
+        for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
+                if (addr[idx])
+                        return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
         }
-        if (!size)
-                return result;
 
-        tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
-        if (tmp == 0UL)         /* Are any bits set? */
-                return result + size;   /* Nope. */
-found:
-        return result + __ffs(tmp);
+        return size;
 }
 EXPORT_SYMBOL(find_first_bit);
 #endif
@@ -141,24 +94,14 @@ EXPORT_SYMBOL(find_first_bit);
  */
 unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
 {
-        const unsigned long *p = addr;
-        unsigned long result = 0;
-        unsigned long tmp;
+        unsigned long idx;
 
-        while (size & ~(BITS_PER_LONG-1)) {
-                if (~(tmp = *(p++)))
-                        goto found;
-                result += BITS_PER_LONG;
-                size -= BITS_PER_LONG;
+        for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
+                if (addr[idx] != ~0UL)
+                        return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);
         }
-        if (!size)
-                return result;
 
-        tmp = (*p) | (~0UL << size);
-        if (tmp == ~0UL)        /* Are any bits zero? */
-                return result + size;   /* Nope. */
-found:
-        return result + ffz(tmp);
+        return size;
 }
 EXPORT_SYMBOL(find_first_zero_bit);
 #endif
@@ -166,18 +109,6 @@ EXPORT_SYMBOL(find_first_zero_bit);
 #ifdef __BIG_ENDIAN
 
 /* include/linux/byteorder does not support "unsigned long" type */
-static inline unsigned long ext2_swabp(const unsigned long * x)
-{
-#if BITS_PER_LONG == 64
-        return (unsigned long) __swab64p((u64 *) x);
-#elif BITS_PER_LONG == 32
-        return (unsigned long) __swab32p((u32 *) x);
-#else
-#error BITS_PER_LONG not defined
-#endif
-}
-
-/* include/linux/byteorder doesn't support "unsigned long" type */
 static inline unsigned long ext2_swab(const unsigned long y)
 {
 #if BITS_PER_LONG == 64
@@ -189,48 +120,38 @@ static inline unsigned long ext2_swab(const unsigned long y)
 #endif
 }
 
-#ifndef find_next_zero_bit_le
-unsigned long find_next_zero_bit_le(const void *addr, unsigned
-                long size, unsigned long offset)
+#if !defined(find_next_bit_le) || !defined(find_next_zero_bit_le)
+static unsigned long _find_next_bit_le(const unsigned long *addr,
+                unsigned long nbits, unsigned long start, unsigned long invert)
 {
-        const unsigned long *p = addr;
-        unsigned long result = offset & ~(BITS_PER_LONG - 1);
         unsigned long tmp;
 
-        if (offset >= size)
-                return size;
-        p += BITOP_WORD(offset);
-        size -= result;
-        offset &= (BITS_PER_LONG - 1UL);
-        if (offset) {
-                tmp = ext2_swabp(p++);
-                tmp |= (~0UL >> (BITS_PER_LONG - offset));
-                if (size < BITS_PER_LONG)
-                        goto found_first;
-                if (~tmp)
-                        goto found_middle;
-                size -= BITS_PER_LONG;
-                result += BITS_PER_LONG;
-        }
+        if (!nbits || start >= nbits)
+                return nbits;
+
+        tmp = addr[start / BITS_PER_LONG] ^ invert;
+
+        /* Handle 1st word. */
+        tmp &= ext2_swab(BITMAP_FIRST_WORD_MASK(start));
+        start = round_down(start, BITS_PER_LONG);
 
-        while (size & ~(BITS_PER_LONG - 1)) {
-                if (~(tmp = *(p++)))
-                        goto found_middle_swap;
-                result += BITS_PER_LONG;
-                size -= BITS_PER_LONG;
+        while (!tmp) {
+                start += BITS_PER_LONG;
+                if (start >= nbits)
+                        return nbits;
+
+                tmp = addr[start / BITS_PER_LONG] ^ invert;
         }
-        if (!size)
-                return result;
-        tmp = ext2_swabp(p);
-found_first:
-        tmp |= ~0UL << size;
-        if (tmp == ~0UL)        /* Are any bits zero? */
-                return result + size; /* Nope. Skip ffz */
-found_middle:
-        return result + ffz(tmp);
 
-found_middle_swap:
-        return result + ffz(ext2_swab(tmp));
+        return min(start + __ffs(ext2_swab(tmp)), nbits);
+}
+#endif
+
+#ifndef find_next_zero_bit_le
+unsigned long find_next_zero_bit_le(const void *addr, unsigned
+                long size, unsigned long offset)
+{
+        return _find_next_bit_le(addr, size, offset, ~0UL);
 }
 EXPORT_SYMBOL(find_next_zero_bit_le);
 #endif
@@ -239,45 +160,7 @@ EXPORT_SYMBOL(find_next_zero_bit_le);
 unsigned long find_next_bit_le(const void *addr, unsigned
                 long size, unsigned long offset)
 {
-        const unsigned long *p = addr;
-        unsigned long result = offset & ~(BITS_PER_LONG - 1);
-        unsigned long tmp;
-
-        if (offset >= size)
-                return size;
-        p += BITOP_WORD(offset);
-        size -= result;
-        offset &= (BITS_PER_LONG - 1UL);
-        if (offset) {
-                tmp = ext2_swabp(p++);
-                tmp &= (~0UL << offset);
-                if (size < BITS_PER_LONG)
-                        goto found_first;
-                if (tmp)
-                        goto found_middle;
-                size -= BITS_PER_LONG;
-                result += BITS_PER_LONG;
-        }
-
-        while (size & ~(BITS_PER_LONG - 1)) {
-                tmp = *(p++);
-                if (tmp)
-                        goto found_middle_swap;
-                result += BITS_PER_LONG;
-                size -= BITS_PER_LONG;
-        }
-        if (!size)
-                return result;
-        tmp = ext2_swabp(p);
-found_first:
-        tmp &= (~0UL >> (BITS_PER_LONG - size));
-        if (tmp == 0UL)         /* Are any bits set? */
-                return result + size; /* Nope. */
-found_middle:
-        return result + __ffs(tmp);
-
-found_middle_swap:
-        return result + __ffs(ext2_swab(tmp));
+        return _find_next_bit_le(addr, size, offset, 0UL);
 }
 EXPORT_SYMBOL(find_next_bit_le);
 #endif