Arm inline Assembly

Inline assembly code, each input and output operand, by the name of the symbol in square brackets [] , A restriction string that consists of a C expression in parentheses

Example

static inline void __down_write (struct rw_semaphore *sem)
{
Long Oldcount;
#ifndef CONFIG_SMP
Oldcount = sem->count;
Sem->count + = Rwsem_active_write_bias;
#else
Long temp;
__asm__ __volatile__ (
"1:ldq_l%0,%1\n"
"Addq%0,%3,%2\n"
"Stq_c%2,%1\n"
"Beq%2,2f\n"
"Mb\n"
". Subsection 2\n"
"2:br 1b\n"
". Previous"
: "=&r" (Oldcount), "=m" (Sem->count), "=&r" (temp)
: "Ir" (Rwsem_active_write_bias), "M" (Sem->count): "Memory");
#endif
if (unlikely (Oldcount))
rwsem_down_write_failed (SEM);
}

Arm inline Assembly