Where 'Uncompressing Linux...' coming from?

I download the zImage of linux provided by hippo.

Upon booting, the terminal reports:

Uncompressing Linux...Ok, booting the kernel

I searched th ewhole code of nios linux ,I found nothing about it....

In i386 arch, there is a function like

------------------------------------

decompress_kernel()

{

puts("Uncompressing Linux... ");

gunzip();

puts("Ok, booting the kernel.\n");

}

--------------------------------------

But nios-linux has not .why?