I am receiving the following error:

flat assembler version 1.73.25 (1048576 kilobytes memory)
afh3eSqr.asm [52]:
cmp r14, 2147483648
processed: cmp r14,2147483648
error: value out of range.

The largest value I can use is 7FFF FFFFh (2,147,483,647)

Wondering why this is so when r14 is a qword ?

Thanks[/i]

In 64-bit mode all immediate encodings are signed 32-bits maximum.

So if you encode 0x8000_0000 as an immediate then it gets sign extended to 0xffff_ffff_8000_000 internally before the cmp is executed.

You can encode all 64-bits with mov.

Thanks