static __always_inline unsigned long __cmpxchg()

in include/asm/cmpxchg.h [87:154]

• 67 lines of code
• 5 McCabe index (conditional complexity)

static __always_inline unsigned long __cmpxchg(unsigned long address,
					       unsigned long old,
					       unsigned long new, int size)
{
	unsigned long prev, tmp;
	int shift;

	switch (size) {
	case 1:
		shift = (3 ^ (address & 3)) << 3;
		address ^= address & 3;
		asm volatile(
			"       l       %0,%2\n"
			"0:     nr      %0,%5\n"
			"       lr      %1,%0\n"
			"       or      %0,%3\n"
			"       or      %1,%4\n"
			"       cs      %0,%1,%2\n"
			"       jnl     1f\n"
			"       xr      %1,%0\n"
			"       nr      %1,%5\n"
			"       jnz     0b\n"
			"1:"
			: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) address)
			: "d" ((old & 0xff) << shift),
			  "d" ((new & 0xff) << shift),
			  "d" (~(0xff << shift))
			: "memory", "cc");
		return prev >> shift;
	case 2:
		shift = (2 ^ (address & 2)) << 3;
		address ^= address & 2;
		asm volatile(
			"       l       %0,%2\n"
			"0:     nr      %0,%5\n"
			"       lr      %1,%0\n"
			"       or      %0,%3\n"
			"       or      %1,%4\n"
			"       cs      %0,%1,%2\n"
			"       jnl     1f\n"
			"       xr      %1,%0\n"
			"       nr      %1,%5\n"
			"       jnz     0b\n"
			"1:"
			: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) address)
			: "d" ((old & 0xffff) << shift),
			  "d" ((new & 0xffff) << shift),
			  "d" (~(0xffff << shift))
			: "memory", "cc");
		return prev >> shift;
	case 4:
		asm volatile(
			"       cs      %0,%3,%1\n"
			: "=&d" (prev), "+Q" (*(int *) address)
			: "0" (old), "d" (new)
			: "memory", "cc");
		return prev;
	case 8:
		asm volatile(
			"       csg     %0,%3,%1\n"
			: "=&d" (prev), "+QS" (*(long *) address)
			: "0" (old), "d" (new)
			: "memory", "cc");
		return prev;
	}
	__cmpxchg_called_with_bad_pointer();
	return old;
}