Look at source for C-file in R package

Question

I'm trying to see the source code for a C file that is used in an R function.

Specifically, it is the fft() function in R. I checked for the fft source with the normal method:

> fft
function (z, inverse = FALSE) 
.Call(C_fft, z, inverse)
<bytecode: 0x0000000008c9e328>
<environment: namespace:stats>

But, .Call suggests that it's actually the C_fft file I'm interested in. However, I have no idea how to find this. I know there's the download.packages() option as per this link. However, the fft()package is in the base package "stats" and in the stats.ll, either of which seem to be available for download.

Thanks for any help.

Edit: Thanks to the first comment for letting me know I'm an idiot who should be more careful.

So in the link I posted, I know it suggests doing the following:

> stats:::C_fft
$name
[1] "fft"

$address
<pointer: 0x00000000003d1ef0>
attr(,"class")
[1] "RegisteredNativeSymbol"

$dll
DLL name: stats
Filename: C:/Program Files/R/R-3.1.0/library/stats/libs/x64/stats.dll
Dynamic lookup: FALSE

$numParameters
[1] 2

attr(,"class")
[1] "CallRoutine"      "NativeSymbolInfo"

That isn't particularly helpful.

However, the Subversion repository allows for a look through all the source files. I found mine in /src/library/stats/src.

Thanks!