quad_arg
A 64-bit quantity, either in a register or in an aligned quadword
memory location.
leq_32bits
Label to branch to if quad_arg is a 32-bit sign-extended value.
gtr_32bits
Label to branch to if quad_arg is greater than 32 bits.
temp_reg=22
Register to use as a temporary register for holding the low
longword of the source value-R22 is the default.