OpenBSD 4.2 released today

OpenBSD 4.2 正式发布,带来了众多改进和新特性,包括新平台支持、安装流程变化、硬件支持增强及新工具等。此版本特别纪念长期开发者 Jun-ichiro “itojun” Itoh Hagino 对 IPv6 的贡献。
<script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script>
Note that 4.2 has install ISO files for most architectures.  They are roughly 230MB in size.  If you choose to use those, please avoid also fetching the base42.tgz, and other such files, since they are included in the ISO image.  If you choose to NOT use the ISO image, then.. well it's kind of obvious.  There is no need to put double the load onto the ftp mirrors.

Enjoy.
Nov 1, 2007.

We are pleased to announce the official release of OpenBSD 4.2.
This is our 22nd release on CD-ROM (and 23rd via FTP).  We remain proud of OpenBSD's record of more than ten years with only two remote holes in the default install.

We dedicate this release to the memory of long-time developer Jun-ichiro "itojun" Itoh Hagino, who focused his life on IPv6 deployment for everyone.  Without his BSD and IETF participation, IPv6 would not be where it is today.  Only now people are becoming aware of his numerous contributions because he took credit for much less than he accomplished.  The developers in our project will all miss him.

As in our previous releases, 4.2 provides significant improvements, including new features, in nearly all areas of the system:

- New/extended platforms:
    o OpenBSD/sparc64.
      The PCIe UltraSPARC IIIi machines like the V215 and V245 are
      now supported.
    o OpenBSD/hppa.
      Four-digit B/C/J-class workstations like the B2000, C3750 or J6750
      are now supported (in 32-bit mode).
    o OpenBSD/alpha.
      Add support in the alpha platform for a couple of new Alpha models,
      AlphaServer 1200 and 4100.

- Platforms skipped this release:
    o OpenBSD/sgi.
      This architecture will not be released this time.

- Install/Upgrade process changes:
    o New install method!!
      For the most popular architectures, the FTP sites have a ~200MB
      install ISO file, which contains the base set, permitting
      non-network installs.
    o Allow the specification of an NTP server during installation.
    o Allow no fsck'ing of clean non-root partitions during upgrade.
    o Check for INSTALL.<arch> to confirm sets are for the correct
      architecture.
    o Create and format the MSDOS partition for macppc installs
      in a more flexible and reliable way.

- Improved hardware support, including:
    o Native Serial-ATA support:
      o ahci(4) driver for SATA controllers conforming to the Advanced
        Host Controller Interface specification.
      o jmb(4) driver for the JMicron JMB36x SATA II and PATA Host Controller.
      o sili(4) driver for SATA controllers using the Silicon Image
        3124/3132/3531 SATALink chipsets.
    o The pciide(4) driver has had support added for newer chipsets, including:
      o Intel ICH8M PATA
      o JMicron JMB36x PATA
      o VIA CX700/VX700 PATA
    o The lm(4) driver now supports Winbond W83627DHG and W83627EHF-A
      Super I/O Hardware Monitors.
    o The siop(4) driver now has support for NCR 53C720/770 controllers in
      big endian mode. In particular this means that the onboard Fast-Wide
      SCSI on many hppa machines is supported now.
    o New tht(4) driver for Tehuti Networks 10Gb Ethernet controllers.
    o The malo(4) driver now supports Marvell 88W8385 802.11g based
      Compact Flash devices.
    o New uts(4) driver for USB touch screens, supported by the xtsscale(1)
      calibration utility.
    o The i810(4) X.Org driver and the PCI AGP driver now support
      Intel i965GM chips.
    o New led(4) driver for the front panel LEDs on the V215/245.
    o New bbc(4) driver providing support for the BootBus Controllers in
      UltraSparc III systems.
    o New pmc(4) driver for the watchdog(4) timer on the National Semiconductor
      PC87317 SuperIO chip.
    o New pyro(4) driver for the SPARC64 Host/PCIe bridge.
    o New astro(4) driver for the Astro Memory and I/O controller on hppa.
    o New elroy(4) driver for the Elroy PCI hostbridge on hppa.
    o New lcd(4) driver for the front panel LCD display on hppa.
    o New ssio(4) driver for the National Semiconductor PC87560 Legacy IO on
      hppa.
    o New pxammc(4) driver for the MMC/SD/SDIO controller on zaurus.
    o New xlights(4) driver for the front panel lights on the Xserve G4.
    o New sysbutton(4) driver for the system identification button on
      the Xserve G4.
    o New piixpcib(4) driver for System Management Mode initiated speedstep
      frequency scaling on certain pairings of the Intel PIIX4 ISA bridges
      and Intel Pentium 3 processors.
    o CPU frequency and voltage can now be scaled on all CPUs when running
      GENERIC.MP on a multiprocessor i386 or AMD64 machine with enhanced
      speedstep or powernow.
    o Intel enhanced speedstep is now supported on OpenBSD/amd64.
    o New support for the on die CPU temperature sensor found on the
      Intel Core family of processors.
    o The nvram(4) driver is now available on OpenBSD/amd64.

- New tools:
    o cwm(1) has replaced wm2 as a simple-looking low-resource window manager.
    o zless(1), view compressed files with less(1).
    o mount_vnd(8), a utility to configure vnode disks from fstab(5).

- New functionality:
    o FFS2, the updated version of the fast file system.
    o ftp(1) now can send cookies loaded from a netscape-like cookiejar,
      supports proxies requiring a password, and has a keep-alive option
      to avoid over-aggressive control connection dropping.
    o pkg_add(1) has been vastly improved. It is more robust, outputs more
      consistent error messages, and can deal with a lot more update
      scenarios gracefully. It also has much better look-up capabilities for
      multiple entries in PKG_PATH, stopping at the first directory with
      suitable candidates.
    o ftp-proxy(8) is now able to automatically tag packets passing through
      the pf(4) rule with a supplied name.
    o Kernel work queues, workq_add_task(9), workq_create(9),
      workq_destroy(9) provides a mechanism to defer tasks to a process
      context when it is impossible to run such a task in the current context.
    o ifconfig(8) now understands IP address/mask in CIDR notation.
    o Add IP (v4 and v6) load balancing to carp(4), similar to the
      ARP balancing.
    o sensorsd(8)  now supports a zero-configuration monitoring and has
      a more intuitive logging for all sensors that automatically provide
      sensor state.  It also features advancements in user-specified
      monitoring, including monitoring of sensors that are periodically
      flagged as invalid.
    o sensorsd.conf(5) now supports sensor matching by sensor type,
      allowing easier configuration.
    o The i386 bootloader can now load amd64 kernels.
    o The amd64 bootloader can now load i386 kernels.

- Assorted improvements and code cleanup:
    o Large (>1TB) disk and partition support in the disklabel and buffer
      cache code and in the userland utilities that manipulate disk blocks.
      Note that some parts of the system are not 64-bit disk block clean
      yet, so partitions larger than 2TB cannot be used at the moment.
    o Large (>2^32-1 sectors) SCSI disk sizes now probed.
    o Thread support for the Objective-C library (libobjc).
    o carp route handling has been fixed, solving some problems the
      routing daemons were exhibiting.
    o Various improvements in pf increase performance drastically,
      stateful passing more than twice as fast than before.
    o A change in how the kernel random pool is stirred increases performance
      with network interface cards that support interrupt mitigation a lot.
    o i386 TLB handling improved to avoid possible corruption on
      Core2Duo processors.
    o Rework TLB shootdown code for i386 and amd64, gives fairly large speed
      improvements.
    o i386 and amd64 use the BIOS disk geometry when creating default
      disklabels.
    o Default disk geometry changed from 64 heads/32 sectors to
      255 heads/63 sectors.
    o More USB devices with various quirks coerced to work.
    o Archive/Wangtek cartridge tape drives (wt*) no longer supported.
    o rcs has improved GNU compatibility.
    o make(1) has improved stability of -j option.

- OpenSSH 4.7:
    o Prevent ssh(1) from using a trusted X11 cookie if creation of an
      untrusted cookie fails.
    o sshd(8) in new installations defaults to SSH Protocol 2 only.
      Existing installations are unchanged.
    o The SSH channel window size has been increased, and both ssh(1)
      sshd(8) now send window updates more aggressively. These improves
      performance on high-BDP (Bandwidth Delay Product) networks.
    o ssh(1) and sshd(8) now preserve MAC contexts between packets, which
      saves 2 hash calls per packet and results in 12-16% speedup for
      arcfour256/hmac-md5.
    o A new MAC algorithm has been added, UMAC-64 (RFC4418) as
      "umac-64@openssh.com". UMAC-64 has been measured to be
      approximately 20% faster than HMAC-MD5.
    o A -K flag was added to ssh(1) to set GSSAPIAuthentication=Yes
    o Failure to establish a ssh(1) TunnelForward is now treated as a
      fatal error when the ExitOnForwardFailure option is set.
    o ssh(1) returns a sensible exit status if the control master goes
      away without passing the full exit status.

- OpenBGPD 4.2:
    o Include support for Four-octet AS Number Space.
    o Allow matching on communities using 0 in the AS part.
    o Filtering on IPv6 prefixes is now possible.
    o Various bugs in the encoding of multiprotocol updates were fixed.
    o Allow the use of pkill -HUP bgpd to reload the config.
    o bgpctl can filter prefix output by community now.

- OpenOSPFD 4.2:
    o Added support for RFC 3137: OSPF Stub Router Advertisement.
    o It is possible to specify a carp demote group on interfaces and areas.
    o Added support for mapping route labels to AS-external route
      tags and vice versa.
    o Allow the use of pkill -HUP ospfd to reload the config.

- HostStated 4.2:
    o Added support for Layer 7 load balancing (or relay).
    o Added support for reloading through hoststatectl or SIGHUP.
    o Added support for testing name-based virtual hosts.

- Over 4,500 ports, minor robustness improvements in package tools.
    o Many pre-built packages for each architecture:
      i386:   4360    sparc64:  4205    alpha: 3779    sh:     817
      amd64:  4283    powerpc:  4230    sparc: 3283    m68k:  1107
      arm:    2131    hppa:     3215  
    o Highlights include:
      o Gnome 2.18.
      o GNUstep 1.14.
      o KDE 3.5.7 and koffice 1.6.3.
      o Xfce 4.4.1.
      o OpenMotif 2.3.0.
      o OpenOffice.org 2.2.1.
      o Mozilla Firefox 2.0.0.6.
      o PostgreSQL 8.2.4.
      o GHC 6.6.1 (amd64 and i386 only)

- As usual, steady improvements in manual pages and other documentation.

- The system includes the following major components from outside
  suppliers:
    o Xenocara (based on X.Org 7.2 + patches, freetype 2.2.1,
      fontconfig 2.4.2, expat 2.0.0, Mesa 6.5.2, xterm 225 and more)
    o Gcc 2.95.3 (+ patches) and 3.3.5 (+ patches)
    o Perl 5.8.8 (+ patches)
    o Our improved and secured version of Apache 1.3, with SSL/TLS and DSO
      support
    o OpenSSL 0.9.7j (+ patches)
    o Groff 1.15
    o Sendmail 8.14.1, with libmilter
    o Bind 9.3.4 (+ patches)
    o Lynx 2.8.5rel.4 with HTTPS and IPv6 support (+ patches)
    o Sudo 1.6.9p4
    o Ncurses 5.2
    o Latest KAME IPv6
    o Heimdal 0.7.2 (+ patches)
    o Arla 0.35.7
    o Binutils 2.15 (+ patches)
    o Gdb 6.3 (+ patches)

If you'd like to see a list of what has changed between OpenBSD 4.1 and 4.2, look at

        http://www.OpenBSD.org/plus42.html

Even though the list is a summary of the most important changes made to OpenBSD, it still is a very very long list.
We provide patches for known security threats and other important issues discovered after each CD release.  As usual, between the creation of the OpenBSD 4.2 FTP/CD-ROM binaries and the actual 4.2 release date, our team found and fixed some new reliability problems
(note: most are minor and in subsystems that are not enabled by default).  Our continued research into security means we will find new security problems -- and we always provide patches as soon as possible.  Therefore, we advise regular visits to

        http://www.OpenBSD.org/security.html
and
    http://www.OpenBSD.org/errata.html

Security patch announcements are sent to the security-announce@OpenBSD.org mailing list.  For information on OpenBSD mailing lists, please see:

    http://www.OpenBSD.org/mail.html
OpenBSD 4.2 is also available on CD-ROM.  The 3-CD set costs $50USD (EUR 50 including VAT) and is available via mail order and from a number of contacts around the world.  The set includes a colourful booklet which carefully explains the installation of OpenBSD.  A new set of cute little stickers is also included (sorry, but our FTP mirror sites do not support STP, the Sticker Transfer Protocol).  As an added bonus, the second CD contains an audio track, a song entitled
"100001 1010101".

Lyrics (and an explanation) for the songs may be found at:

    http://www.OpenBSD.org/lyrics.html#42

Profits from CD sales are the primary income source for the OpenBSD project -- in essence selling these CD-ROM units ensures that OpenBSD will continue to make another release six months from now.

The OpenBSD 4.2 CD-ROMs are bootable on the following four platforms:

  o i386
  o amd64
  o macppc
  o sparc64

(Other platforms must boot from floppy, network, or other method).

For more information on ordering CD-ROMs, see:

        http://www.OpenBSD.org/orders.html

The above web page lists a number of places where OpenBSD CD-ROMs can be purchased from.  For our default mail order, go directly to:

        https://https.OpenBSD.org/cgi-bin/order

or, for European orders:

    https://https.OpenBSD.org/cgi-bin/order.eu

All of our developers strongly urge you to buy a CD-ROM and support our future efforts.  Additionally, donations to the project are highly appreciated, as described in more detail at:

        http://www.OpenBSD.org/goals.html#funding
For those unable to make their contributions as straightforward gifts, the OpenBSD Foundation (http://www.openbsdfoundation.org) is a Canadian not-for-profit corporation that can accept larger contributions and issue receipts.  In some situations, their receipt may qualify as a business expense writeoff, so this is certainly a consideration for some organizations or businesses.  There may also be exposure benefits since the Foundation may be interested in participating in press releases.
In turn, the Foundation then uses these contributions to assist OpenBSD's infrastructure needs.  Contact the foundation directors at directors@openbsdfoundation.org for more information.
The project continues to expand its funding base by selling t-shirts and polo shirts.  And our users like them too.  We have a variety of shirts available, with the new and old designs, from our web ordering system at:

        https://https.OpenBSD.org/cgi-bin/order

and for Europe:

    https://https.OpenBSD.org/cgi-bin/order.eu

The OpenBSD 4.2 t-shirts are available now. The new shirt for 4.2 has a newly drawn version of Puffy (the blowfish) on a simple black shirt.
We also sell our older shirts, as well as a selection of OpenSSH t-shirts.
If you choose not to buy an OpenBSD CD-ROM, OpenBSD can be easily installed via FTP.  Typically you need a single small piece of boot media (e.g., a boot floppy) and then the rest of the files can be installed from a number of locations, including directly off the Internet.  Follow this simple set of instructions to ensure that you find all of the documentation you will need while performing an install via FTP.  With the CD-ROMs, the necessary documentation is easier to find.

1) Read either of the following two files for a list of ftp
   mirrors which provide OpenBSD, then choose one near you:

        http://www.OpenBSD.org/ftp.html
        ftp://ftp.OpenBSD.org/pub/OpenBSD/4.2/ftplist

   As of Nov 1, 2007, the following ftp mirror sites have the 4.2 release:

    ftp://ftp.kd85.com/pub/OpenBSD/4.2/        Austria
    ftp://ftp.stacken.kth.se/pub/OpenBSD/4.2/    Sweden
    ftp://ftp2.usa.openbsd.org/pub/OpenBSD/4.2/    NYC, USA
    ftp://ftp3.usa.openbsd.org/pub/OpenBSD/4.2/    CO, USA
    ftp://ftp5.usa.openbsd.org/pub/OpenBSD/4.2/    CA, USA
    ftp://rt.fm/pub/OpenBSD/4.2/            IL, USA

    The release is also available at the master site:

    ftp://ftp.openbsd.org/pub/OpenBSD/4.2/    Alberta, Canada
   
    However it is strongly suggested you use a mirror.

   Other mirror sites may take a day or two to update.

2) Connect to that ftp mirror site and go into the directory
   pub/OpenBSD/4.2/ which contains these files and directories.
   This is a list of what you will see:

        ANNOUNCEMENT   amd64/         macppc/        sys.tar.gz
        Changelogs/    armish/        mvme68k/       tools/
        HARDWARE       ftplist        packages/      vax/
        PACKAGES       hp300/         ports.tar.gz   xenocara.tar.gz
        PORTS          hppa/          root.mail      zaurus/
        README         i386/          sparc/
        SIZES          landisk/       sparc64/
        alpha/         mac68k/        src.tar.gz

                   
   It is quite likely that you will want at LEAST the following
   files which apply to all the architectures OpenBSD supports.

        README          - generic README
        HARDWARE        - list of hardware we support
        PORTS           - description of our "ports" tree
        PACKAGES        - description of pre-compiled packages
        root.mail       - a copy of root's mail at initial login.
              (This is really worthwhile reading).

3) Read the README file.  It is short, and a quick read will make
   sure you understand what else you need to fetch.

4) Next, go into the directory that applies to your architecture,
   for example, i386.  This is a list of what you will see:

    INSTALL.i386    cd42.iso        floppyB42.fs    pxeboot*
    INSTALL.linux   cdboot*         floppyC42.fs    xbase42.tgz
    MD5             cdbr*           game42.tgz      xetc42.tgz
    base42.tgz      cdemu42.iso     index.txt       xfont42.tgz
    bsd*            comp42.tgz      install42.iso   xserv42.tgz
    bsd.mp*         etc42.tgz       man42.tgz       xshare42.tgz
    bsd.rd*         floppy42.fs     misc42.tgz

   If you are new to OpenBSD, fetch _at least_ the file INSTALL.i386
   and the appropriate floppy*.fs or install42.iso files.  Consult the
   INSTALL.i386 file if you don't know which of the floppy images
   you need (or simply fetch all of them).

   If you use the install42.iso file (roughly 200MB in size), then you
   do not need the various *.tgz files since they are contained on that
   one-step ISO-format install CD.

5) If you are an expert, follow the instructions in the file called
   README; otherwise, use the more complete instructions in the
   file called INSTALL.i386.  INSTALL.i386 may tell you that you
   need to fetch other files.

6) Just in case, take a peek at:

        http://www.OpenBSD.org/errata.html

   This is the page where we talk about the mistakes we made while
   creating the 4.2 release, or the significant bugs we fixed
   post-release which we think our users should have fixes for.
   Patches and workarounds are clearly described there.

Note: If you end up needing to write a raw floppy using Windows,
      you can use "fdimage.exe" located in the pub/OpenBSD/4.2/tools
      directory to do so.
X.Org has been integrated more closely into the system.  This release contains X.Org 7.2.0.  Most of our architectures ship with X.Org, including amd64, sparc, sparc64 and macppc.  During installation, you can install X.Org quite easily.  Be sure to try out xdm(1) and see how we have customized it for OpenBSD.
The OpenBSD ports tree contains automated instructions for building third party software.  The software has been verified to build and run on the various OpenBSD architectures.  The 4.2 ports collection, including many of the distribution files, is included on the 3-CD set.  Please see the PORTS file for more information.

Note: some of the most popular ports, e.g., the Apache web server and several X applications, come standard with OpenBSD.  Also, many popular ports have been pre-compiled for those who do not desire to build their own binaries (see BINARY PACKAGES, below).
A large number of binary packages are provided.  Please see the PACKAGES file (ftp://ftp.OpenBSD.org/pub/OpenBSD/4.2/PACKAGES) for more details.
The CD-ROMs contain source code for all the subsystems explained above, and the README (ftp://ftp.OpenBSD.org/pub/OpenBSD/4.2/README)
file explains how to deal with these source files.  For those who are doing an FTP install, the source code for all four subsystems can be found in the pub/OpenBSD/4.2/ directory:

        xenocara.tar.gz     ports.tar.gz   src.tar.gz     sys.tar.gz
OpenBSD 4.2 includes artwork and CD artistic layout by Ty Semaka, who also arranged an audio track on the OpenBSD 4.2 CD set.  Ports tree and package building by Antoine Jacoutot, Peter Valchev, Robert Nagy and Christian Weisgerber.  System builds by Theo de Raadt, Kenji Aoyama, and Miod Vallat.  X11 builds by Todd Fries.  ISO-9660 filesystem layout by Theo de Raadt.

We would like to thank all of the people who sent in bug reports, bug fixes, donation cheques, and hardware that we use.  We would also like to thank those who pre-ordered the 4.2 CD-ROM or bought our previous CD-ROMs.  Those who did not support us financially have still helped us with our goal of improving the quality of the software.

Our developers are:

    Alexandre Anriot, Antoine Jacoutot, Aleksander Piotrowski,
    Kenji Aoyama, Artur Grabowski, Anil Madhavapeddy, Bob Beck,
    Bernd Ahlers, Bjorn Sandell, Alexander Bluhm, Camiel Dobbelaar,
    Can Erkin Acar, David Cathcart, Charles Longeau, Chris Kuethe,
    Claudio Jeker, Chad Loder, Constantine A. Murenin, Damien Couderc,
    Damien Bergamini, Dan Harnett, David Collins, David Krause,
    David Berghoff, Deanna Phillips, Theo de Raadt, Daniel Hartmeier,
    David Hill, Dimitry Andric, Damien Miller, David Gwynne,
    Don Stewart, Dale Rahn, Darren Tucker, Eric Faurot, Marc Espie,
    Federico G. Schwindt, Felix Kronlage, Mike Frantzen, Gilles Chehade
    Alexander Yurchenko, Alexander von Gernler, Gordon Willem Klok,
    Henning Brauer, Henric Jungheim, Hans Insulander, Hakan Olsson,
    Hans-Joerg Hoexer, Hugh Graham, Ian Darwin,
    Jun-ichiro "itojun" Itoh Hagino, Jakob Schlyter, Jared Yanovich,
    Jason Wright, Jacob Meuser, Jasper Lievisse Adriaanse, Joshua Stein,
    Jason Dixon, Janne Johansson, Jason McIntyre, Joel Knight,
    Jolan Luff, Jordan Hargrave, Joris Vink, Jonathan Gray,
    Jan-Uwe Finck, Mark Kettenis, Kevin Lo, Matthias Kilian,
    Kenjiro Cho, Kjell Wooding, Kenneth R Westerback, Kurt Miller,
    Mats O Jansson, Marco S Hyman, Marco Peereboom, Marc Matteo,
    Markus Friedl, Martin Reindl, Martynas Venckus, Matthieu Herrb,
    Marc Balmer, Ryan Thomas McBride, Michael Erdely, Marcus Glocker,
    Moritz Grimm, Michele Marchetto, Todd C. Miller, Miod Vallat,
    Michael Coulter, Michael Knudsen, Moritz Jodeit,
    Marco Pfatschbacher, Mathieu Sauve-Frankel, Christian Weisgerber,
    Nathan Binkert, Niall O'Higgins, Nick Holland, Nils Nordman,
    Esben Norby, Thomas Nordin, Otto Moerbeek, Christopher Pascoe,
    Patrick Latifi, Philipp Buehler, Peter Valchev,
    Pierre-Yves Ritschard, Alexandre Ratchov, Ray Lai, Robert Nagy,
    Reyk Floeter, Rui Reis, Saad Kadhi, Simon Bertrang,
    Stephen Kirkham, Igor Sobrado, Steven Mestdagh, Kevin Steves,
    Stuart Henderson, Nikolay Sturm, Ted Unangst,
    Thordur I. Bjornsson, Tobias Stoeckmann, Todd T.  Fries,
    Tom Cosgrove, Uwe Stuehler, Tobias Weingartner, Peter Stromberg,
    Marc Winiger, Wim Vandeputte, Xavier Santolaria.

 
已经博主授权,源码转载自 https://pan.quark.cn/s/053f1da40351 在计算机科学领域,MIPS(Microprocessor without Interlocked Pipeline Stages)被视作一种精简指令集计算机(RISC)的架构,其应用广泛存在于教学实践和嵌入式系统设计中。 本篇内容将深入阐释MIPS汇编语言中涉及数组处理的核心概念与实用操作技巧。 数组作为一种常见的数据结构,在编程中能够以有序化的形式储存及访问具有相同类型的数据元素集合。 在MIPS汇编语言环境下,数组通常借助内存地址与索引进行操作。 以下列举了运用MIPS汇编处理数组的关键要素:1. **数据存储**: - MIPS汇编架构采用32位地址系统,从而能够访问高达4GB的内存容量。 - 数组元素一般以连续方式存放在内存之中,且每个元素占据固定大小的字节空间。 例如,针对32位的整型数组,其每个元素将占用4字节的存储空间。 - 数组首元素的地址被称为基地址,而数组任一元素的地址可通过基地址加上元素索引乘以元素尺寸的方式计算得出。 2. **寄存器运用**: - MIPS汇编系统配备了32个通用寄存器,包括$zero, $t0, $s0等。 其中,$zero寄存器通常用于表示恒定的零值,$t0-$t9寄存器用于暂存临时数据,而$s0-$s7寄存器则用于保存子程序的静态变量或参数。 - 在数组处理过程中,基地址常被保存在$s0或$s1寄存器内,索引则存储在$t0或$t1寄存器中,运算结果通常保存在$v0或$v1寄存器。 3. **数组操作指令**: - **Load/Store指令**:这些指令用于在内存与寄存器之间进行数据传输,例如`lw`指令用于加载32位数据至寄存器,`sw`指令...
根据原作 https://pan.quark.cn/s/cb681ec34bd2 的源码改编 基于Python编程语言完成的飞机大战项目,作为一项期末学习任务,主要呈现了游戏开发的基本概念和技术方法。 该项目整体构成约500行代码,涵盖了游戏的核心运作机制、图形用户界面以及用户互动等关键构成部分。 该项目配套提供了完整的源代码文件、相关技术文档、项目介绍演示文稿以及运行效果展示视频,为学习者构建了一个实用的参考范例,有助于加深对Python在游戏开发领域实际应用的认识。 我们进一步研究Python编程技术在游戏开发中的具体运用。 Python作为一门高级编程语言,因其语法结构清晰易懂和拥有丰富的库函数支持,在开发者群体中获得了广泛的认可和使用。 在游戏开发过程中,Python经常与Pygame库协同工作,Pygame是Python语言下的一款开源工具包,它提供了构建2D游戏所需的基础功能模块,包括窗口系统管理、事件响应机制、图形渲染处理、音频播放控制等。 在"飞机大战"这一具体游戏实例中,开发者可能运用了以下核心知识点:1. **Pygame基础操作**:掌握如何初始化Pygame环境,设定窗口显示尺寸,加载图像和音频资源,以及如何启动和结束游戏的主循环流程。 2. **面向对象编程**:游戏中的飞机、子弹、敌人等游戏元素通常通过类的设计来实现,利用实例化机制来生成具体的游戏对象。 每个类都定义了自身的属性(例如位置坐标、移动速度、生命值状态)和方法(比如移动行为、碰撞响应、状态更新)。 3. **事件响应机制**:Pygame能够捕获键盘输入和鼠标操作事件,使得玩家可以通过按键指令来控制飞机的移动和射击行为。 游戏会根据这些事件的发生来实时更新游戏场景状态。 4. **图形显示与刷新**:...
【顶级SCI复现】高比例可再生能源并网如何平衡灵活性与储能成本?虚拟电厂多时间尺度调度及衰减建模(Matlab代码实现)内容概要:本文围绕高比例可再生能源并网背景下虚拟电厂的多时间尺度调度与储能成本优化问题展开研究,重点探讨如何在保证系统灵活性的同时降低储能配置与运行成本。通过构建多时间尺度(如日前、日内、实时)协调调度模型,并引入储能设备衰减建模,提升调度精度与经济性。研究结合Matlab代码实现,复现顶级SCI论文中的优化算法与建模方法,涵盖鲁棒优化、分布鲁棒、模型预测控制(MPC)等先进手段,兼顾风光出力不确定性与需求响应因素,实现虚拟电厂内部多能源协同优化。; 适合人群:具备一定电力系统基础知识和Matlab编程能力的研究生、科研人员及从事新能源、智能电网、能源互联网领域的工程技术人员。; 使用场景及目标:① 掌握虚拟电厂多时间尺度调度的核心建模思路与实现方法;② 学习如何将储能寿命衰减纳入优化模型以提升经济性;③ 复现高水平SCI论文中的优化算法与仿真流程,服务于科研论文写作与项目开发。; 阅读建议:建议结合文中提供的Matlab代码逐模块分析,重点关注目标函数设计、约束条件构建及求解器调用过程,配合实际案例数据进行调试与验证,深入理解优化模型与物理系统的映射关系。
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值