| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Network Checksum & Copy routine |
| * |
| * Copyright (C) 1999, 2003-2004 Hewlett-Packard Co |
| * Stephane Eranian <eranian@hpl.hp.com> |
| * |
| * Most of the code has been imported from Linux/Alpha |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/string.h> |
| |
| #include <net/checksum.h> |
| |
| /* |
| * XXX Fixme: those 2 inlines are meant for debugging and will go away |
| */ |
| static inline unsigned |
| short from64to16(unsigned long x) |
| { |
| /* add up 32-bit words for 33 bits */ |
| x = (x & 0xffffffff) + (x >> 32); |
| /* add up 16-bit and 17-bit words for 17+c bits */ |
| x = (x & 0xffff) + (x >> 16); |
| /* add up 16-bit and 2-bit for 16+c bit */ |
| x = (x & 0xffff) + (x >> 16); |
| /* add up carry.. */ |
| x = (x & 0xffff) + (x >> 16); |
| return x; |
| } |
| |
| static inline |
| unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum) |
| { |
| int odd, count; |
| unsigned long result = (unsigned long)psum; |
| |
| if (len <= 0) |
| goto out; |
| odd = 1 & (unsigned long) buff; |
| if (odd) { |
| result = *buff << 8; |
| len--; |
| buff++; |
| } |
| count = len >> 1; /* nr of 16-bit words.. */ |
| if (count) { |
| if (2 & (unsigned long) buff) { |
| result += *(unsigned short *) buff; |
| count--; |
| len -= 2; |
| buff += 2; |
| } |
| count >>= 1; /* nr of 32-bit words.. */ |
| if (count) { |
| if (4 & (unsigned long) buff) { |
| result += *(unsigned int *) buff; |
| count--; |
| len -= 4; |
| buff += 4; |
| } |
| count >>= 1; /* nr of 64-bit words.. */ |
| if (count) { |
| unsigned long carry = 0; |
| do { |
| unsigned long w = *(unsigned long *) buff; |
| count--; |
| buff += 8; |
| result += carry; |
| result += w; |
| carry = (w > result); |
| } while (count); |
| result += carry; |
| result = (result & 0xffffffff) + (result >> 32); |
| } |
| if (len & 4) { |
| result += *(unsigned int *) buff; |
| buff += 4; |
| } |
| } |
| if (len & 2) { |
| result += *(unsigned short *) buff; |
| buff += 2; |
| } |
| } |
| if (len & 1) |
| result += *buff; |
| |
| result = from64to16(result); |
| |
| if (odd) |
| result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); |
| |
| out: |
| return result; |
| } |
| |
| /* |
| * XXX Fixme |
| * |
| * This is very ugly but temporary. THIS NEEDS SERIOUS ENHANCEMENTS. |
| * But it's very tricky to get right even in C. |
| */ |
| __wsum |
| csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum) |
| { |
| memcpy(dst, src, len); |
| return csum_partial(dst, len, sum); |
| } |
| |
| EXPORT_SYMBOL(csum_partial_copy_nocheck); |