Public Domain or No Binary Attribution FFT Lib?
I'm looking for an FFT library to translate into the D programming language for inclusion either in a library that I'm working on or (better yet) in the standard library.  I need a fairly simple FFT with decent performance, not an uber-optimized one with blazing fast performance and zero simplicity/readability.  However, it must meet the following requirements:

1.  Either written in pure D or simple enough to be reasonably translatable to pure D.  For example, readable C code without any inline assembler or preprocessor abuse would work.  (I'm aware that you can call C from D, but I have my reasons for not wanting to.)

2.  Licensed under terms that are free/open-source, non-copyleft (i.e. not GPL) and do not require attribution for binary-only distribution (i.e. not BSD).  Acceptable licenses include Boost, zlib and public domain.

3.  The code must be readable enough that I can sanely modify it to give it a nice D interface.  I **do not** want super-optimized but unreadable Fortran code from the '70s, no matter how well it works.  I also don't want C code that was translated from super-optimized Fortran code and looks like Fortran code.

Please **do not suggest FFTW** no matter how good it is (I understand it's very good), as it's both GPL licensed and written for performance over simplicity.
Public Domain or No Binary Attribution FFT Lib?
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I'm looking for an FFT library to translate into the D programming language for inclusion either in a library that I'm working on or (better yet) in the standard library.  I need a fairly simple FFT with decent performance, not an uber-optimized one with blazing fast performance and zero simplicity/readability.  However, it must meet the following requirements:

1.  Either written in pure D or simple enough to be reasonably translatable to pure D.  For example, readable C code without any inline assembler or preprocessor abuse would work.  (I'm aware that you can call C from D, but I have my reasons for not wanting to.)

2.  Licensed under terms that are free/open-source, non-copyleft (i.e. not GPL) and do not require attribution for binary-only distribution (i.e. not BSD).  Acceptable licenses include Boost, zlib and public domain.

3.  The code must be readable enough that I can sanely modify it to give it a nice D interface.  I **do not** want super-optimized but unreadable Fortran code from the '70s, no matter how well it works.  I also don't want C code that was translated from super-optimized Fortran code and looks like Fortran code.

Please **do not suggest FFTW** no matter how good it is (I understand it's very good), as it's both GPL licensed and written for performance over simplicity.