| /* |
| * Copyright (c) 1992, 1993, 1994, 1995, 1996 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that: (1) source code distributions |
| * retain the above copyright notice and this paragraph in its entirety, (2) |
| * distributions including binary code include the above copyright notice and |
| * this paragraph in its entirety in the documentation or other materials |
| * provided with the distribution, and (3) all advertising materials mentioning |
| * features or use of this software display the following acknowledgement: |
| * ``This product includes software developed by the University of California, |
| * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of |
| * the University nor the names of its contributors may be used to endorse |
| * or promote products derived from this software without specific prior |
| * written permission. |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED |
| * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
| * |
| * @(#) $Header: /tcpdump/master/tcpdump/extract.h,v 1.25 2006-01-30 16:20:07 hannes Exp $ (LBL) |
| */ |
| |
| /* |
| * Macros to extract possibly-unaligned big-endian integral values. |
| */ |
| #ifdef LBL_ALIGN |
| /* |
| * The processor doesn't natively handle unaligned loads. |
| */ |
| #ifdef HAVE___ATTRIBUTE__ |
| /* |
| * We have __attribute__; we assume that means we have __attribute__((packed)). |
| * Declare packed structures containing a u_int16_t and a u_int32_t, |
| * cast the pointer to point to one of those, and fetch through it; |
| * the GCC manual doesn't appear to explicitly say that |
| * __attribute__((packed)) causes the compiler to generate unaligned-safe |
| * code, but it apppears to do so. |
| * |
| * We do this in case the compiler can generate, for this instruction set, |
| * better code to do an unaligned load and pass stuff to "ntohs()" or |
| * "ntohl()" than the code to fetch the bytes one at a time and |
| * assemble them. (That might not be the case on a little-endian platform, |
| * where "ntohs()" and "ntohl()" might not be done inline.) |
| */ |
| typedef struct { |
| u_int16_t val; |
| } __attribute__((packed)) unaligned_u_int16_t; |
| |
| typedef struct { |
| u_int32_t val; |
| } __attribute__((packed)) unaligned_u_int32_t; |
| |
| #define EXTRACT_16BITS(p) \ |
| ((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) + 0)->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 |
| * quantities the hard way - fetch the bytes one at a time and |
| * assemble them. |
| */ |
| #define EXTRACT_16BITS(p) \ |
| ((u_int16_t)((u_int16_t)*((const u_int8_t *)(p) + 0) << 8 | \ |
| (u_int16_t)*((const u_int8_t *)(p) + 1))) |
| #define EXTRACT_32BITS(p) \ |
| ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 0) << 24 | \ |
| (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_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) + 6) << 8 | \ |
| (u_int64_t)*((const u_int8_t *)(p) + 7))) |
| #endif /* HAVE___ATTRIBUTE__ */ |
| #else /* LBL_ALIGN */ |
| /* |
| * The processor natively handles unaligned loads, so we can just |
| * cast the pointer and fetch through it. |
| */ |
| #define EXTRACT_16BITS(p) \ |
| ((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) \ |
| ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 0) << 16 | \ |
| (u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \ |
| (u_int32_t)*((const u_int8_t *)(p) + 2))) |
| |
| /* |
| * 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 | \ |
| (u_int16_t)*((const u_int8_t *)(p) + 0))) |
| #define EXTRACT_LE_32BITS(p) \ |
| ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 3) << 24 | \ |
| (u_int32_t)*((const u_int8_t *)(p) + 2) << 16 | \ |
| (u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \ |
| (u_int32_t)*((const u_int8_t *)(p) + 0))) |
| #define EXTRACT_LE_24BITS(p) \ |
| ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 2) << 16 | \ |
| (u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \ |
| (u_int32_t)*((const u_int8_t *)(p) + 0))) |
| #define EXTRACT_LE_64BITS(p) \ |
| ((u_int64_t)((u_int64_t)*((const u_int8_t *)(p) + 7) << 56 | \ |
| (u_int64_t)*((const u_int8_t *)(p) + 6) << 48 | \ |
| (u_int64_t)*((const u_int8_t *)(p) + 5) << 40 | \ |
| (u_int64_t)*((const u_int8_t *)(p) + 4) << 32 | \ |
| (u_int64_t)*((const u_int8_t *)(p) + 3) << 24 | \ |
| (u_int64_t)*((const u_int8_t *)(p) + 2) << 16 | \ |
| (u_int64_t)*((const u_int8_t *)(p) + 1) << 8 | \ |
| (u_int64_t)*((const u_int8_t *)(p) + 0))) |