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Don't do the "OR together the result of two "ntohl()"s stuff on

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platforms that don't support unaligned fetches - just assemble the
64-bit big-endian integer from its constituent bytes.

Improve some comments.
This commit is contained in:
guy 2004-09-25 06:48:14 +00:00
parent f3fce4b301
commit 923f10c8b8
1 changed files with 24 additions and 9 deletions
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33
extract.h
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@ -18,11 +18,12 @@
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* @(#) $Header: /tcpdump/master/tcpdump/extract.h,v 1.21 2004-09-24 18:21:25 guy Exp $ (LBL)
* @(#) $Header: /tcpdump/master/tcpdump/extract.h,v 1.22 2004-09-25 06:48:14 guy Exp $ (LBL)
*/
/* Network to host order macros */
/*
* Macros to extract possibly-unaligned big-endian integral values.
*/
#ifdef LBL_ALIGN
/*
* The processor doesn't natively handle unaligned loads.
@ -54,6 +55,10 @@ typedef struct {
((u_int16_t)ntohs(((const unaligned_u_int16_t *)(p))->val))
#define EXTRACT_32BITS(p) \
((u_int32_t)ntohl(((const unaligned_u_int32_t *)(p))->val))
#define EXTRACT_64BITS(p) \
((u_int64_t)(((u_int64_t)ntohl(((const unaligned_u_int32_t *)(p))->val) << 32 | \
((u_int64_t)ntohl(((const unaligned_u_int32_t *)(p) + 1)->val)) << 0))
#else /* HAVE___ATTRIBUTE__ */
/*
* We don't have __attribute__, so do unaligned loads of big-endian
@ -68,6 +73,15 @@ typedef struct {
(u_int32_t)*((const u_int8_t *)(p) + 1) << 16 | \
(u_int32_t)*((const u_int8_t *)(p) + 2) << 8 | \
(u_int32_t)*((const u_int8_t *)(p) + 3)))
#define EXTRACT_LE_64BITS(p) \
((u_int64_t)((u_int64_t)*((const u_int8_t *)(p) + 0) << 56 | \
(u_int64_t)*((const u_int8_t *)(p) + 1) << 48 | \
(u_int64_t)*((const u_int8_t *)(p) + 2) << 40 | \
(u_int64_t)*((const u_int8_t *)(p) + 3) << 32 | \
(u_int64_t)*((const u_int8_t *)(p) + 4) << 24 | \
(u_int64_t)*((const u_int8_t *)(p) + 5) << 16 | \
(u_int64_t)*((const u_int8_t *)(p) + 7) << 8 | \
(u_int64_t)*((const u_int8_t *)(p) + 7)))
#endif /* HAVE___ATTRIBUTE__ */
#else /* LBL_ALIGN */
/*
@ -78,6 +92,9 @@ typedef struct {
((u_int16_t)ntohs(*(const u_int16_t *)(p)))
#define EXTRACT_32BITS(p) \
((u_int32_t)ntohl(*(const u_int32_t *)(p)))
#define EXTRACT_64BITS(p) \
((u_int64_t)(((u_int64_t)ntohl(*((const u_int32_t *)(p) + 0))) << 32 | \
((u_int64_t)ntohl(*((const u_int32_t *)(p) + 1))) << 0))
#endif /* LBL_ALIGN */
#define EXTRACT_24BITS(p) \
@ -85,12 +102,10 @@ typedef struct {
(u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \
(u_int32_t)*((const u_int8_t *)(p) + 2)))
#define EXTRACT_64BITS(p) \
((u_int64_t)(u_int64_t)(EXTRACT_32BITS((p) + 0)) << 32 | \
(u_int64_t)(EXTRACT_32BITS((p) + 4)))
/* Little endian protocol host order macros */
/*
* Macros to extract possibly-unaligned little-endian integral values.
* XXX - do loads on little-endian machines that support unaligned loads?
*/
#define EXTRACT_LE_8BITS(p) (*(p))
#define EXTRACT_LE_16BITS(p) \
((u_int16_t)((u_int16_t)*((const u_int8_t *)(p) + 1) << 8 | \