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[PATCH 1/1] include/qemu/bitops.h: Add deposit8 for uint8_t bit operatio


From: Jason Fan
Subject: [PATCH 1/1] include/qemu/bitops.h: Add deposit8 for uint8_t bit operation
Date: Mon, 26 Aug 2024 20:46:28 +0000

Signed-off-by: Jason Fan <fanjason@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 2c0a2fe751..d01c4b42f2 100644
--- a/include/qemu/bitops.h
+++ b/include/qemu/bitops.h
@@ -459,6 +459,32 @@ static inline int64_t sextract64(uint64_t value, int 
start, int length)
     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
 }
 
+/**
+ * deposit8:
+ * @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 8 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 8 bit word.
+ * It is valid to request that all 8 bits are modified (ie @length
+ * 8 and @start 0).
+ *
+ * Returns: the modified @value.
+ */
+static inline uint8_t deposit8(uint8_t value, int start, int length,
+                               uint8_t fieldval)
+{
+    uint8_t mask = 0xFF;
+    assert(start >= 0 && length > 0 && length <= 8 - start);
+    mask = (mask >> (8 - length)) << start;
+    return (value & ~mask) | ((fieldval << start) & mask);
+}
+
 /**
  * deposit32:
  * @value: initial value to insert bit field into
-- 
2.46.0.295.g3b9ea8a38a-goog




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