The second is not farther: 
s/__(\S+)__/\U$1/g

[download]
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re^2: another string replacement with uppercase :: converting C macros to C++ by choroba
in thread another string replacement with uppercase :: converting C macros to C++ by f77coder

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