1 // SPDX-License-Identifier: GPL-2.0
3  * arch/x86_64/lib/csum-partial.c
6  * in an architecture-specific manner due to speed.
12 #include <asm/word-at-a-time.h>
14 static inline unsigned short from32to16(unsigned a)   in from32to16()  argument
16 	unsigned short b = a >> 16;   in from32to16()
20 	    : "0" (b), "r" (a));  in from32to16()
25  * Do a checksum on an arbitrary memory area.
26  * Returns a 32bit checksum.
33  * it's best to have buff aligned on a 64-bit boundary
44 		temp64 = ror32((__force u32)sum, 8);  in csum_partial()
45 		temp64 += (*(unsigned char *)buff << 8);  in csum_partial()
46 		len--;  in csum_partial()
51 		asm("addq 0*8(%[src]),%[res]\n\t"  in csum_partial()
52 		    "adcq 1*8(%[src]),%[res]\n\t"  in csum_partial()
53 		    "adcq 2*8(%[src]),%[res]\n\t"  in csum_partial()
54 		    "adcq 3*8(%[src]),%[res]\n\t"  in csum_partial()
55 		    "adcq 4*8(%[src]),%[res]\n\t"  in csum_partial()
56 		    "adcq 5*8(%[src]),%[res]\n\t"  in csum_partial()
57 		    "adcq 6*8(%[src]),%[res]\n\t"  in csum_partial()
58 		    "adcq 7*8(%[src]),%[res]\n\t"  in csum_partial()
64 		len -= 64;  in csum_partial()
68 		asm("addq 0*8(%[src]),%[res]\n\t"  in csum_partial()
69 		    "adcq 1*8(%[src]),%[res]\n\t"  in csum_partial()
70 		    "adcq 2*8(%[src]),%[res]\n\t"  in csum_partial()
71 		    "adcq 3*8(%[src]),%[res]\n\t"  in csum_partial()
79 		asm("addq 0*8(%[src]),%[res]\n\t"  in csum_partial()
80 		    "adcq 1*8(%[src]),%[res]\n\t"  in csum_partial()
87 	if (len & 8) {  in csum_partial()
88 		asm("addq 0*8(%[src]),%[res]\n\t"  in csum_partial()
93 		buff += 8;  in csum_partial()
96 		unsigned int shift = (8 - (len & 7)) * 8;  in csum_partial()
109 		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);  in csum_partial()
116  * this routine is used for miscellaneous IP-like checksums, mainly