How to test your code on a machine with big-endian architecture?

QEMU supports emulating several big-endian architectures. Note that some architectures support both endiannesses; some (Itanium, ARM) are primarily used as little-endian while others (PowerPC, MIPS) are primarily used as big-endian.

Aurélien Jarno wrote some HOWTOs on installing Debian on an emulated MIPS or SPARC machine which should be a good start.

Googling "big endian online emulator" lead me to PearPC. I assume that if you have the patience you can install Mandrake Linux, get gcc, and go party.

If you are using Ubuntu, you can download MIPS cross compiler (or any other big-endian architecture that is supported by QEMU, and has a prebuilt cross compiler), and QEMU-user, then compile your code in static linkage, and just run it.

sudo apt-get install gcc-multilib-mips-linux-gnu gcc-mips-linux-gnu qemu-user

and then

mips-linux-gnu-gcc test.c -o test -static
qemu-mips ./test