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authorAlex Beregszaszi <alex@rtfs.hu>2017-08-11 00:47:35 +0800
committerAlex Beregszaszi <alex@rtfs.hu>2017-08-11 00:47:35 +0800
commit9358001ba4074d94d9daa566d225e1f8b2305009 (patch)
treea149408a7be68fc4d391aed0b9a36b14f209c39b
parent34503d98d7d95fc3a55a60be854809524c1f204e (diff)
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Use temporary variable for sum example
-rw-r--r--docs/assembly.rst18
1 files changed, 10 insertions, 8 deletions
diff --git a/docs/assembly.rst b/docs/assembly.rst
index 377a6530..bdb708a9 100644
--- a/docs/assembly.rst
+++ b/docs/assembly.rst
@@ -104,19 +104,21 @@ you really know what you are doing.
let len := mload(_data)
// Skip over the length field.
- _data := add(_data, 0x20)
+ //
+ // Keep temporary variable so it can be incremented in place.
+ //
+ // NOTE: incrementing _data would result in an unusable
+ // _data variable after this assembly block
+ let data := add(_data, 0x20)
// Iterate until the bound is not met.
for
- { let end := add(_data, len) }
- lt(_data, end)
- { _data := add(_data, 0x20) }
+ { let end := add(data, len) }
+ lt(data, end)
+ { data := add(data, 0x20) }
{
- o_sum := add(o_sum, mload(_data))
+ o_sum := add(o_sum, mload(data))
}
-
- // NOTE: after this point it is not safe to use _data in Solidity code
- // because its offsets are in an invalid position
}
}
}