[PATCH v3 1/5] bitops.h: add deposit16 function

[Titus Rwantare <titusr@google.com>]

Makes it more explicit that 16 bit values are being used

Signed-off-by: Titus Rwantare <titusr@google.com>
---
 include/qemu/bitops.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
index 03213ce952..887b8f8ce8 100644
--- a/include/qemu/bitops.h
+++ b/include/qemu/bitops.h
@@ -446,6 +446,32 @@ static inline int64_t sextract64(uint64_t value, int start, int length)
     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
 }
 
+/**
+ * deposit16:
+ * @value: initial value to insert bit field into
+ * @start: the lowest bit in the bit field (numbered from 0)
+ * @length: the length of the bit field
+ * @fieldval: the value to insert into the bit field
+ *
+ * Deposit @fieldval into the 16 bit @value at the bit field specified
+ * by the @start and @length parameters, and return the modified
+ * @value. Bits of @value outside the bit field are not modified.
+ * Bits of @fieldval above the least significant @length bits are
+ * ignored. The bit field must lie entirely within the 16 bit word.
+ * It is valid to request that all 16 bits are modified (ie @length
+ * 16 and @start 0).
+ *
+ * Returns: the modified @value.
+ */
+static inline uint16_t deposit16(uint16_t value, int start, int length,
+                                 uint16_t fieldval)
+{
+    uint16_t mask;
+    assert(start >= 0 && length > 0 && length <= 16 - start);
+    mask = (~0U >> (16 - length)) << start;
+    return (value & ~mask) | ((fieldval << start) & mask);
+}
+
 /**
  * deposit32:
  * @value: initial value to insert bit field into
-- 
2.40.0.rc1.284.g88254d51c5-goog