alpha/lib/checksum.c

1 // SPDX-License-Identifier: GPL-2.0
6  * in an architecture-specific manner due to speed..
10  *	Rick Gorton	<rick.gorton@alpha-processor.com>
42  * computes the checksum of the TCP/UDP pseudo-header
43  * returns a 16-bit checksum, already complemented.
62 	/* Fold down to 32-bits so we don't lose in the typedef-less   in csum_tcpudp_nofold()
73  * Do a 64-bit checksum on an arbitrary memory area..
77  * ways to do the carry, but this is reasonable.
89 		len--;  in do_csum()
92 	count = len >> 1;		/* nr of 16-bit words.. */  in do_csum()
96 			count--;  in do_csum()
97 			len -= 2;  in do_csum()
100 		count >>= 1;		/* nr of 32-bit words.. */  in do_csum()
104 				count--;  in do_csum()
105 				len -= 4;  in do_csum()
108 			count >>= 1;	/* nr of 64-bit words.. */  in do_csum()
110 				unsigned long carry = 0;  in do_csum()  local
113 					count--;  in do_csum()
115 					result += carry;  in do_csum()
117 					carry = (w > result);  in do_csum()
119 				result += carry;  in do_csum()
153  * and adds in "sum" (32-bit)
155  * returns a 32-bit number suitable for feeding into itself
161  * it's best to have buff aligned on a 32-bit boundary
167 	/* add in old sum, and carry.. */  in csum_partial()
169 	/* 32+c bits -> 32 bits */  in csum_partial()
177  * this routine is used for miscellaneous IP-like checksums, mainly