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Use temporary variable for sum example

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This commit is contained in:
Alex Beregszaszi 2017-08-10 17:47:35 +01:00
parent 34503d98d7
commit 9358001ba4
1 changed files with 10 additions and 8 deletions
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18
docs/assembly.rst
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@ -104,19 +104,21 @@ you really know what you are doing.
let len := mload(_data) let len := mload(_data)
// Skip over the length field. // 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. // Iterate until the bound is not met.
for for
{ let end := add(_data, len) } { let end := add(data, len) }
lt(_data, end) lt(data, end)
{ _data := add(_data, 0x20) } { 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
} }
} }
} }