[PATCH v3 01/11] sandbox: add generic find_next_zero_bit implementation

[lukas.funke-oss at weidmueller.com]

From: Lukas Funke <lukas.funke at weidmueller.com>

Add generic 'find_next_zero_bit()' implementation in order to enable the
use of the 'for_each_set_bitrange' macro. The implementation is currently
missing for the sandbox-arch and using the function results in a linker
error. The implementation is copied from the 'arm' implementation.

Signed-off-by: Lukas Funke <lukas.funke at weidmueller.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
---

Changes in v3:
- Use generic find_next_zero_bit() from arch/arm/include/asm/bitops.h
- Redirect sandbox ffz() implementation to generic __ffs() impl

 arch/sandbox/include/asm/bitops.h | 60 +++++++++++++++++++------------
 1 file changed, 38 insertions(+), 22 deletions(-)

diff --git a/arch/sandbox/include/asm/bitops.h b/arch/sandbox/include/asm/bitops.h
index f27d5e98c5..6950916962 100644
--- a/arch/sandbox/include/asm/bitops.h
+++ b/arch/sandbox/include/asm/bitops.h
@@ -104,9 +104,6 @@ static inline int __test_and_change_bit(int nr, void *addr)
 	return (old & mask) != 0;
 }
 
-extern int find_first_zero_bit(void *addr, unsigned size);
-extern int find_next_zero_bit(void *addr, int size, int offset);
-
 /*
  * This routine doesn't need to be atomic.
  */
@@ -119,27 +116,46 @@ static inline int test_bit(int nr, const void *addr)
  * ffz = Find First Zero in word. Undefined if no zero exists,
  * so code should check against ~0UL first..
  */
-static inline unsigned long ffz(unsigned long word)
-{
-	int k;
-
-	word = ~word;
-	k = 31;
-	if (word & 0x0000ffff) {
-		k -= 16; word <<= 16;
-	}
-	if (word & 0x00ff0000) {
-		k -= 8;  word <<= 8;
-	}
-	if (word & 0x0f000000) {
-		k -= 4;  word <<= 4;
+#define ffz(x)  __ffs(~(x))
+
+#define find_first_zero_bit(addr, size) \
+	find_next_zero_bit((addr), (size), 0)
+
+static inline int find_next_zero_bit(const unsigned long *addr, int size,
+				     int offset) {
+	unsigned long *p = ((unsigned long *)addr) + (offset / BITS_PER_LONG);
+	unsigned long result = offset & ~(BITS_PER_LONG - 1);
+	unsigned long tmp;
+
+	if (offset >= size)
+		return size;
+	size -= result;
+	offset &= (BITS_PER_LONG - 1);
+	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;
 	}
-	if (word & 0x30000000) {
-		k -= 2;  word <<= 2;
+	while (size & ~(BITS_PER_LONG - 1)) {
+		tmp = *(p++);
+		if (~tmp)
+			goto found_middle;
+		result += BITS_PER_LONG;
+		size -= BITS_PER_LONG;
 	}
-	if (word & 0x40000000)
-		k -= 1;
-	return k;
+	if (!size)
+		return result;
+	tmp = *p;
+
+found_first:
+	tmp |= ~0UL << size;
+found_middle:
+	return result + ffz(tmp);
 }
 
 /*
-- 
2.30.2