patch: clean up msdosfs conversion routine

From: Nate Lawson (nate_at_root.org)
Date: 03/06/05

  • Next message: Nate Lawson: "patch: optimize mbnambuf routines in msdosfs" 
    Date: Sat, 05 Mar 2005 23:42:18 -0800
To: arch@freebsd.org

    The attached patch optimizes the unix2win conversion routine. It uses
    16 bit accesses instead of 8 bit and jumps to "out" once it hits the
    trailing NUL rather than drop through each loop. I'd like to make sure
    my use of the endian routines is correct, if someone can check this.

    Thanks, 

    -- 
Nate

    Index: msdosfs_conv.c
    ===================================================================
    RCS file: /home/ncvs/src/sys/fs/msdosfs/msdosfs_conv.c,v
    retrieving revision 1.39
    diff -u -r1.39 msdosfs_conv.c
    --- msdosfs_conv.c 8 Feb 2005 07:51:14 -0000 1.39
    +++ msdosfs_conv.c 2 Mar 2005 17:48:52 -0000
    @@ -52,6 +52,7 @@
      * System include files.
      */
     #include <sys/param.h>
    +#include <sys/endian.h>
     #include <sys/time.h>
     #include <sys/kernel.h> /* defines tz */
     #include <sys/systm.h>
    @@ -708,9 +711,8 @@
             int chksum;
             struct msdosfsmount *pmp;
     {
    - u_int8_t *wcp;
    - int i, end;
    - u_int16_t code;
    + u_int16_t *wcp;
    + int end, i;
     
             /*
              * Drop trailing blanks and dots
    @@ -726,7 +728,7 @@
             /*
              * Initialize winentry to some useful default
              */
    - for (wcp = (u_int8_t *)wep, i = sizeof(*wep); --i >= 0; *wcp++ = 0xff);
    + memset(wep, 0xff, sizeof(*wep));
             wep->weCnt = cnt;
             wep->weAttributes = ATTR_WIN95;
             wep->weReserved1 = 0;
    @@ -737,29 +739,34 @@
              * Now convert the filename parts
              */
             end = 0;
    - for (wcp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0 && !end;) {
    - code = unix2winchr(&un, &unlen, 0, pmp);
    - *wcp++ = code;
    - *wcp++ = code >> 8;
    - if (!code)
    + wcp = (uint16_t *)wep->wePart1;
    + for (i = sizeof(wep->wePart1)/2; --i >= 0;) {
    + *wcp = htole16(unix2winchr(&un, &unlen, 0, pmp));
    + if (*wcp++ == 0) {
                             end = WIN_LAST;
    + goto out;
    + }
             }
    - for (wcp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0 && !end;) {
    - code = unix2winchr(&un, &unlen, 0, pmp);
    - *wcp++ = code;
    - *wcp++ = code >> 8;
    - if (!code)
    + wcp = (uint16_t *)wep->wePart2;
    + for (i = sizeof(wep->wePart2)/2; --i >= 0;) {
    + *wcp = htole16(unix2winchr(&un, &unlen, 0, pmp));
    + if (*wcp++ == 0) {
                             end = WIN_LAST;
    + goto out;
    + }
             }
    - for (wcp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0 && !end;) {
    - code = unix2winchr(&un, &unlen, 0, pmp);
    - *wcp++ = code;
    - *wcp++ = code >> 8;
    - if (!code)
    + wcp = (uint16_t *)wep->wePart3;
    + for (i = sizeof(wep->wePart3)/2; --i >= 0;) {
    + *wcp = htole16(unix2winchr(&un, &unlen, 0, pmp));
    + if (*wcp++ == 0) {
                             end = WIN_LAST;
    + goto out;
    + }
             }
             if (*un == '\0')
                     end = WIN_LAST;
    +
    +out:
             wep->weCnt |= end;
             return !end;
     }

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