static __inline__ __sum16 ip_fast_csum()

in include/asm/checksum.h [88:121]

• 29 lines of code
• 1 McCabe index (conditional complexity)

static __inline__ __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
	unsigned int sum, tmp, endaddr;

	__asm__ __volatile__(
		"sub		%0, %0, %0\n\t"
#if XCHAL_HAVE_LOOPS
		"loopgtz	%2, 2f\n\t"
#else
		"beqz		%2, 2f\n\t"
		"slli		%4, %2, 2\n\t"
		"add		%4, %4, %1\n\t"
		"0:\t"
#endif
		"l32i		%3, %1, 0\n\t"
		"add		%0, %0, %3\n\t"
		"bgeu		%0, %3, 1f\n\t"
		"addi		%0, %0, 1\n\t"
		"1:\t"
		"addi		%1, %1, 4\n\t"
#if !XCHAL_HAVE_LOOPS
		"blt		%1, %4, 0b\n\t"
#endif
		"2:\t"
	/* Since the input registers which are loaded with iph and ihl
	   are modified, we must also specify them as outputs, or gcc
	   will assume they contain their original values. */
		: "=r" (sum), "=r" (iph), "=r" (ihl), "=&r" (tmp),
		  "=&r" (endaddr)
		: "1" (iph), "2" (ihl)
		: "memory");

	return	csum_fold(sum);
}