Thanks for answering sir habran
well, I'm getting this result using HJWasm. Maybe my version is older or because is that I'm trying to generate elf file, follows the code.
;hjwasm -elf64 -Fo=test.o test.hjwasm
.x64
.code
public _start
_start:
mov rax,0123456789abcdefh
end
HJWasm v2.14, Jun 9 2016, Masm-compatible assembler.
test.hjwasm(6) : Error A2235: Constant value too large: 123456789ABCDEFh
test.hjwasm: 7 lines, 1 passes, 329 ms, 0 warnings, 1 errors