netbsd源码分析（1）

今天想开始一个工程，分析NETBSD，工程比我想像的浩大，希望能在n个月内完成。

NetBSD是一个免费的，具有高度移植性的 UNIX-like 操作系统，是现行可移植平台最多的操作系统，可以在许多平台上执行，从 64bit alpha 服务器到手持设备和嵌入式设备。NetBSD计划的口号是："Of course it runs NetBSD"。它设计简洁，代码规范，拥有众多先进特性，使得它在业界和学术界广受好评。由于简洁的设计和先进的特征，使得它在生产和研究方面，都有卓越的表现，而且它也有受使用者支持的完整的源代码。许多程序都可以很容易地通过NetBSD Packages Collection获得。

本博客所有内容是原创，如果转载请注明来源

http://blog.csdn.net/myhaspl/

下面开始吧～

src/sys/sys/time.h

/* $NetBSD: time.h,v 1.65 2011/10/27 16:12:52 christos Exp $ */

/*
* Copyright (c) 1982, 1986, 1993
*   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 the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. 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 BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*   @(#)time.h   8.5 (Berkeley) 5/4/95
*/

定义系统时间的头文件，看来这个time.h是关于时间格式等操作的系统头文件。
#ifndef _SYS_TIME_H_
#define _SYS_TIME_H_

#include <sys/featuretest.h>
#include <sys/types.h>

/*
* Structure returned by gettimeofday(2) system call,
* and used in other calls.
*/
struct timeval {
time_t tv_sec; /* seconds */
suseconds_t tv_usec; /* and microseconds */
};

/*
* Structure defined by POSIX.1b to be like a timeval.
*/
struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* and nanoseconds */
};

来看看types.h

/* $NetBSD: types.h,v 1.88 2011/01/14 02:06:34 rmind Exp $ */

/*-
* Copyright (c) 1982, 1986, 1991, 1993, 1994
*   The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. 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 BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*   @(#)types.h   8.4 (Berkeley) 1/21/94
*/

#ifndef _SYS_TYPES_H_
#define _SYS_TYPES_H_

#include <sys/featuretest.h>

/* Machine type dependent parameters. */
#include <machine/types.h>

#include <machine/ansi.h>
#include <machine/int_types.h>

#include <sys/ansi.h>

#ifndef   int8_t
typedef   __int8_t   int8_t;
#define   int8_t       __int8_t
#endif

#ifndef   uint8_t
typedef   __uint8_t   uint8_t;
#define   uint8_t       __uint8_t
#endif

#ifndef   int16_t
typedef   __int16_t   int16_t;
#define   int16_t       __int16_t
#endif

#ifndef   uint16_t
typedef   __uint16_t   uint16_t;
#define   uint16_t   __uint16_t
#endif

#ifndef   int32_t
typedef   __int32_t   int32_t;
#define   int32_t       __int32_t
#endif

#ifndef   uint32_t
typedef   __uint32_t   uint32_t;
#define   uint32_t   __uint32_t
#endif

#ifndef   int64_t
typedef   __int64_t   int64_t;
#define   int64_t       __int64_t
#endif

#ifndef   uint64_t
typedef   __uint64_t   uint64_t;
#define   uint64_t   __uint64_t
#endif

typedef   uint8_t       u_int8_t;
typedef   uint16_t   u_int16_t;
typedef   uint32_t   u_int32_t;
typedef   uint64_t   u_int64_t;
是对变量类型的别名的定义，可能是为了方便移植，有趣的是还定义了bool类型

#if defined(_KERNEL) || defined(_STANDALONE)
/*
* Boolean type definitions for the kernel environment. User-space
* boolean definitions are found in <stdbool.h>.
*/
#define bool   _Bool
#define true   1
#define false   0

/*
* Deprecated Mach-style boolean_t type. Should not be used by new code.
*/
typedef int   boolean_t;
#ifndef TRUE
#define   TRUE   1
#endif
#ifndef FALSE
#define   FALSE   0
#endif

对很多内核中的地址以及设备号的C类型以及格式，比如其内存表示，typedef uint64_t dev_t; typedef int64_t daddr_t;
具体如下：

#if !defined(_KERNEL) && !defined(_STANDALONE)
/* We don't and shouldn't use caddr_t in the kernel anymore */
#ifndef   caddr_t
typedef   __caddr_t   caddr_t;   /* core address */
#define   caddr_t       __caddr_t
#endif
#endif

#ifdef __daddr_t
typedef __daddr_t daddr_t; /* disk address */
#undef __daddr_t
#else
typedef int64_t daddr_t; /* disk address */
#endif

typedef uint64_t dev_t; /* device number */
typedef uint32_t fixpt_t; /* fixed point number */