[PATCH v4 06/18] bitops.h: Add find_first_bit32()

set_bit32()/test_bit32()/etc already let devices operate on
guest-visible uint32_t register arrays without depending on the host's
'unsigned long' size.  Add find_first_bit32() so callers need not cast
a uint32_t array to 'unsigned long *'.

Reviewed-by: Pierrick Bouvier <[email protected]>
Signed-off-by: Brian Cain <[email protected]>
---
 include/qemu/bitops.h | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
index c7b838a6283..f7363a5479f 100644
--- a/include/qemu/bitops.h
+++ b/include/qemu/bitops.h
@@ -43,10 +43,9 @@
  * be some guest-visible register view of the bit array.
  *
  * We do not currently implement uint32_t versions of find_last_bit(),
- * find_next_bit(), find_next_zero_bit(), find_first_bit() or
- * find_first_zero_bit(), because we haven't yet needed them. If you
- * need them you should implement them similarly to the 'unsigned long'
- * versions.
+ * find_next_bit(), find_next_zero_bit() or find_first_zero_bit(),
+ * because we haven't yet needed them. If you need them you should
+ * implement them similarly to the 'unsigned long' versions.
  *
  * You can declare a bitmap to be used with these functions via the
  * DECLARE_BITMAP and DECLARE_BITMAP32 macros in bitmap.h.
@@ -382,6 +381,29 @@ static inline int test_bit32(long nr, const uint32_t *addr)
     return 1U & (addr[BIT32_WORD(nr)] >> (nr & 31));
 }
 
+/**
+ * find_first_bit32 - find the first set bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The maximum size to search
+ *
+ * Returns the bit number of the first set bit,
+ * or @size if there is no set bit in the bitmap.
+ */
+static inline uint32_t find_first_bit32(const uint32_t *addr, uint32_t size)
+{
+    uint32_t result;
+
+    for (result = 0; result < size; result += 32) {
+        uint32_t tmp = *addr++;
+        if (tmp) {
+            result += ctz32(tmp);
+            return result < size ? result : size;
+        }
+    }
+    /* Not found */
+    return size;
+}
+
 /**
  * DOC: Miscellaneous bit operations on single values
  *
-- 
2.34.1