With what parameters does echo call fwrite? Trying to implement fwrite in Nim.

[khaledh-nim]

Here's how I implemented 
[fwrite](https://github.com/khaledh/axiom/blob/e8c96c564c476a1d67ae372f8dfbab2dfdc74c5d/src/lib/libc.nim#L75-L83)
 in my [kernel](https://github.com/khaledh/axiom):
    
    
    type
      constCstringImpl {.importc: "const char *".} = cstring
      constCstring = distinct constCstringImpl
      
      constPointerImpl {.importc: "const void *".} = pointer
      constPointer = distinct constPointerImpl
    
    type
      CFile {.importc: "FILE", header: "<stdio.h>", incompleteStruct.} = object
      CFilePtr* = ptr CFile ## The type representing a file handle.
    
    proc fwrite*(buf {.noalias.}: constPointer, size, n: csize_t, f 
{.noalias.}: CFilePtr): csize_t
        {.exportc.} =
      let p = cast[ptr UncheckedArray[char]](buf)
      for i in 0..(n*size):
        print(&"{p[i]}")
    
    
    Run

In my case `print` uses the UEFI [Simple Text Output 
protocol](https://uefi.org/specs/UEFI/2.9_A/12_Protocols_Console_Support.html#efi-simple-text-output-protocol)
 instead of writing directly to the framebuffer, but that's beside the point.