SPRUI04F july 2015 – april 2023
In Example5-4, the expression "q3:q2:q1:q0" means that the first argument into the linear assembly function is a register quad. By the C calling conventions, the quad "q3:q2:q1:q0" symbols are mapped to register quad "a7:a6:a5:a4". When a register quad syntax is used as the argument to a .reg directive (as shown), it means that the four register symbols are constrained to be an aligned register quad when the compiler processes the linear assembler source and allocates actual registers that the register quad symbols map to "r3:r2:r1:r0" as shown.