Solidity Inline Assembly Example 1

pragma solidity ^0.4.0;

library GetCode {
    function at(address _codeAddr) returns (bytes o_codeArray) {
        assembly {
            // get the code size, need assembly for this
            let codeSize := externalcodesize(_codeAddr)
            // allocate output byte array - you can do this without assembly as well
            // with o_codeArray = new bytes(codeSize)
            o_codeArray := mload(0x40)
            // newly created "memory end" that includes padding
            mstore(0x40, add(o_codeArray, and(add(add(codeSize, 0x20), 0x1f), not(0x1f))))
            // length of store in the memory
            mstore(o_codeArray, codeSize)
            // get the code , need assembly for this
            externalcodecopy(_codeAddr, add(o_codeArray, 0x20), 0, codeSize)
        }
    }
}