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author | Ulrich Drepper <drepper@redhat.com> | 1999-04-28 23:13:52 +0000 |
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committer | Ulrich Drepper <drepper@redhat.com> | 1999-04-28 23:13:52 +0000 |
commit | c4563d2d668675c2d5083f6ad01c801d6ccbe013 (patch) | |
tree | 1e6af86f8c33743c81080dffb17a8e8209825c06 /sysdeps/i386/strchrnul.S | |
parent | 89afc233db58d3de7669332d141113ec2ca4991d (diff) | |
download | glibc-c4563d2d668675c2d5083f6ad01c801d6ccbe013.tar.gz glibc-c4563d2d668675c2d5083f6ad01c801d6ccbe013.tar.xz glibc-c4563d2d668675c2d5083f6ad01c801d6ccbe013.zip |
Update.
1999-04-28 Ulrich Drepper <drepper@cygnus.com> * argp/argp-ba.c (argp_program_bug_address): Don't initialize with 0. * argp/argp-parse.c (_argp_hang): Likewise. * argp/argp-pv.c (argp_program_version): Likewise. * argp/argp-pvh.c (argp_program_version_hook): Likewise. * inet/ether_hton.c (ether_hton, startp): Likewise. * inet/ether_ntoh.c (ether_ntoh, startp): Likewise. * inet/getnetgrent_r.c (setup, startp): Likewise. * intl/loadmsgcat.c (_nl_msg_cat_cntr): Likewise. * intl/localealias.c (string_space, string_space_act, string_space_max, nmap, maxmap): Likewise. * libio/iopopen.c (proc_file_chain): Likewise. * libio/oldiopopen.c (old_proc_file_chain): Likewise. * locale/lc-collate.c (__collate_table, __collate_extra, __collate_element_hash, __collate_element_strings, __collate_element_values): Likewise. * malloc/mcheck.c (mcheck_used): Likewise. * malloc/mtrace.c (added_atexit_handler): Likewise. * malloc/set-freeres.c (already_called): Likewise. * misc/getpass.c (getpass) [buf, bufsize]: Likewise. * misc/syslog.c (LogStat, LogTag): Likewise. * nss/XXX-lookup.c (DATABASE_NAME_SYMBOL): Likewise. * nss/getXXbyYY_r.c (startp): Likewise. * posix/getopt.c (optarg, __getopt_initialized): Likewise. * posix/regex.c (init_syntax_once) [done]: Likewise. (debug): Likewise. * string/strfry.c (init): Likewise. * sunrpc/svc_run.c (svc_top): Likewise. * posix/euidaccess.c (have_ids): Likewise. * sysdeps/unix/sysv/linux/poll.c (must_emulate): Likewise. * sysdeps/unix/sysv/linux/ttyname.c (__ttyname, namelen): Likewise. * time/getdate.c (getdate_err): Likewise. * time/tzfile.c (transitions, type_idxs, types, zone_names, leaps): Likewise. * time/tzset.c (old_tz, is_initialized): Likewise. * inet/getnameinfo.c (nrl_domainname): Rewrite to allow initialization of static data with zero. * signal/allocrtsig.c (init): Likewise. * string/Makefile (routines): Add strchrnul. * string/Versions [GLIBC_2.1.1]: Add strchrnul. * string/string.c: Add strchrnul prototype. * include/string.h: Add __strchrnul prototype. * sysdeps/generic/strchrnul.c: New file. * sysdeps/i386/strchrnul.S: New file. * sysdeps/i386/bits/string.c: Add strchrnul optimization. * sysdeps/i386/i486/bits/string.c: Likewise. * argp/argp-help.c (argp_args_usage): Use __strchrnul. * inet/ether_line.c (ether_line): Likewise. * nscd/nscd_conf.c (nscd_parse_file): Likewise. * nss/nsswitch.c (nss_parse_file): Likewise. * posix/execvp.c (execvp): Likewise. * posix/fnmatch.c (internal_fnmatch): Likewise. * resolv/res_hconf.c (_res_hconv_init): Likewise. * resolv/res_init.c (res_init): Likewise. * stdlib/fmtmsg.c (init): Likewise. * stdlib/getsubopt.c (getsubopt): Likewise. * catgets/catgets.c (catopen): Only allocate one memory block. (catclose): Only one free call necessary. * catgets/open_catalog.c (__open_catalog): Simplify handling of file descriptor. * ctype/ctype-extn.c: Make __toascii_l and __isascii_l alias instead of real functions. Simplify _tolower and _toupper. * grp/initgroups.c (compat_call): Remove unnecessary use of pointer variable. * iconv/gconv.h (struct gconv_info): Change data element from pointer to array of size 0. * iconv/gconv_open.c (__gconv_open): Allocate structures accordingly. * iconv/gconv_close.c (__gconv_close): Don't free data. * iconv/gconv_conf.c (add_alias): Avoid searching in tree twice to insert new alias. * iconv/gconv_db.c (add_derivation): More efficient copying. Check for error while inserting in tree. * include/time.h: Pretty print. * inet/ruserpass.c: Rewrite use of toktab to avoid string pointers in table and lots of relocations. * posix/regex.c (regerror): Rewrite use of re_error_msgid to avoid string pointers in table and lots of relocations. * intl/finddomain.c: Remove definition of strchr macro. * io/ftw.c (nftw_arr, ftw_arr): Make const. * locale/loadlocale.c (_nl_load_locale): Optimize string copying. * locale/localeinfo.h (_nl_category_names): Change into an array with fixed width char string elements. * locale/setlocale.c (_nl_category_names): Likewise. (_nl_current): Make global. * locale/nl_langinfo.c (nldata): Removed. Use _nl_current now. * malloc/Makefile (distribute): Add stackinfo.h. * sysdeps/generic/stackinfo.h: New file. * sysdeps/i386/stackinfo.h: New file. * posix/execl.c: Use stackinfo.h in optimizing alloca use. * posix/execle.c: Likewise. * posix/execlp.c: Likewise. * nis/nis_table.c (__create_ib_request): Always use realloc. * posix/execvp.c (execute): Rename to script_execute and keep only code to execute using shell. (execvp): Call execv directly and only fall back on script_execute. * resolv/inet_net_pton.c (inet_net_pton_ipv4): Remove digits define and always use xdigits instead. * resolv/res_init.c (res_init): Use rawmemchr instead of strchr where appropriate. * stdlib/fpioconst.h (__tens): New declaration. (struct mp_power): Remove array, add arrayoff element. * stdlib/fpioconst.c: Replace definitions of _ten_p* arrays by one __tens array and add in _fpioconst_pow10 offsets into __tens. * stdio-common/printf_fp.c: Rewrite to use new __tens array. * stdlib/strtod.c: Likewise. * stdlib/a64l.c (a64l_table): Avoid unnecessary elements. * stdlib/exit.c: Rewrite to use __exit_funcs being as sign for end of the list. * stdlib/atexit.c (__exit_funcs): Don't initialize. * stdlib/fmtmsg.c (keywords): Make name element fixed width array. * sunrpc/clnt_perr.c: Rewrite clnt_sperrno and auth_errmsg to use a single and an array with offsets. * sunrpc/des_soft.c (partab): Make it const. * sunrpc/key_call.c (trytimeout, tottimeout): Make const. (__key_encryptsession_pk_LOCAL): Don't initialize with 0. (__key_decryptsession_pk_LOCAL): Likewise. (__key_gendes_LOCAL): Likewise. (MESSENGER): Mark const. (key_call_private_main): Don't initialize with 0. (use_keyenvoy): Don't initialize with 0. (key_call): Rewrite to reverse logic of use_doors variable. * sunrpc/netname.c (OPSYS): Define as array, not pointer. (startp): Don't initialize with zero. * sunrpc/openchild.c (_openchild): Make first argument const. * sunrpc/pmap_rmt.c (timeout): Mark const. * sunrpc/xcrypt.c (hex): Likewise. * sysdeps/unix/sysv/linux/getcwd.c: Rewrite to allow omitting initialization of global variables. * sysdeps/unix/sysv/linux/getpt.c: Likewise. * sysdeps/unix/sysv/linux/if_index.c: Likewise. * termios/tcgetsid.c: Likewise. * sysdeps/unix/sysv/linux/i386/dl-procinfo.h (x86_cap_flags): Change fxsr to osfxsr. * time/tzfile.c (__tzfile_read): Rewrite to allocate only one memory block. Add function to free memory if wanted. * time/tzset.c (tzset_internal): Pass extra argument to __tzfile_read. * wcsmbs/wcsmbsload.c (to_wc, to_mb): Correct initializers. * wcsmbs/wmemset.c: Little code optimization.
Diffstat (limited to 'sysdeps/i386/strchrnul.S')
-rw-r--r-- | sysdeps/i386/strchrnul.S | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/sysdeps/i386/strchrnul.S b/sysdeps/i386/strchrnul.S new file mode 100644 index 0000000000..45950c3564 --- /dev/null +++ b/sysdeps/i386/strchrnul.S @@ -0,0 +1,275 @@ +/* strchrnul (str, ch) -- Return pointer to first occurrence of CH in STR + or the final NUL byte. + For Intel 80x86, x>=3. + Copyright (C) 1994, 1995, 1996, 1997, 1999 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@gnu.org> + Some optimisations by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au> + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <sysdep.h> +#include "asm-syntax.h" + +/* + INPUT PARAMETERS: + str (sp + 4) + ch (sp + 8) +*/ + + .text +ENTRY (__strchrnul) + pushl %edi /* Save callee-safe registers used here. */ + + movl 8(%esp), %eax /* get string pointer */ + movl 12(%esp), %edx /* get character we are looking for */ + + /* At the moment %edx contains C. What we need for the + algorithm is C in all bytes of the dword. Avoid + operations on 16 bit words because these require an + prefix byte (and one more cycle). */ + movb %dl, %dh /* now it is 0|0|c|c */ + movl %edx, %ecx + shll $16, %edx /* now it is c|c|0|0 */ + movw %cx, %dx /* and finally c|c|c|c */ + + /* Before we start with the main loop we process single bytes + until the source pointer is aligned. This has two reasons: + 1. aligned 32-bit memory access is faster + and (more important) + 2. we process in the main loop 32 bit in one step although + we don't know the end of the string. But accessing at + 4-byte alignment guarantees that we never access illegal + memory if this would not also be done by the trivial + implementation (this is because all processor inherent + boundaries are multiples of 4. */ + + testb $3, %eax /* correctly aligned ? */ + jz L(11) /* yes => begin loop */ + movb (%eax), %cl /* load byte in question (we need it twice) */ + cmpb %cl, %dl /* compare byte */ + je L(6) /* target found => return */ + testb %cl, %cl /* is NUL? */ + jz L(6) /* yes => return NULL */ + incl %eax /* increment pointer */ + + testb $3, %eax /* correctly aligned ? */ + jz L(11) /* yes => begin loop */ + movb (%eax), %cl /* load byte in question (we need it twice) */ + cmpb %cl, %dl /* compare byte */ + je L(6) /* target found => return */ + testb %cl, %cl /* is NUL? */ + jz L(6) /* yes => return NULL */ + incl %eax /* increment pointer */ + + testb $3, %eax /* correctly aligned ? */ + jz L(11) /* yes => begin loop */ + movb (%eax), %cl /* load byte in question (we need it twice) */ + cmpb %cl, %dl /* compare byte */ + je L(6) /* target found => return */ + testb %cl, %cl /* is NUL? */ + jz L(6) /* yes => return NULL */ + incl %eax /* increment pointer */ + + /* No we have reached alignment. */ + jmp L(11) /* begin loop */ + + /* We exit the loop if adding MAGIC_BITS to LONGWORD fails to + change any of the hole bits of LONGWORD. + + 1) Is this safe? Will it catch all the zero bytes? + Suppose there is a byte with all zeros. Any carry bits + propagating from its left will fall into the hole at its + least significant bit and stop. Since there will be no + carry from its most significant bit, the LSB of the + byte to the left will be unchanged, and the zero will be + detected. + + 2) Is this worthwhile? Will it ignore everything except + zero bytes? Suppose every byte of LONGWORD has a bit set + somewhere. There will be a carry into bit 8. If bit 8 + is set, this will carry into bit 16. If bit 8 is clear, + one of bits 9-15 must be set, so there will be a carry + into bit 16. Similarly, there will be a carry into bit + 24. If one of bits 24-31 is set, there will be a carry + into bit 32 (=carry flag), so all of the hole bits will + be changed. + + 3) But wait! Aren't we looking for C, not zero? + Good point. So what we do is XOR LONGWORD with a longword, + each of whose bytes is C. This turns each byte that is C + into a zero. */ + + /* Each round the main loop processes 16 bytes. */ + + ALIGN(4) + +L(1): addl $16, %eax /* adjust pointer for whole round */ + +L(11): movl (%eax), %ecx /* get word (= 4 bytes) in question */ + xorl %edx, %ecx /* XOR with word c|c|c|c => bytes of str == c + are now 0 */ + movl $0xfefefeff, %edi /* magic value */ + addl %ecx, %edi /* add the magic value to the word. We get + carry bits reported for each byte which + is *not* C */ + + /* According to the algorithm we had to reverse the effect of the + XOR first and then test the overflow bits. But because the + following XOR would destroy the carry flag and it would (in a + representation with more than 32 bits) not alter then last + overflow, we can now test this condition. If no carry is signaled + no overflow must have occurred in the last byte => it was 0. */ + jnc L(7) + + /* We are only interested in carry bits that change due to the + previous add, so remove original bits */ + xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ + + /* Now test for the other three overflow bits. */ + orl $0xfefefeff, %edi /* set all non-carry bits */ + incl %edi /* add 1: if one carry bit was *not* set + the addition will not result in 0. */ + + /* If at least one byte of the word is C we don't get 0 in %edi. */ + jnz L(7) /* found it => return pointer */ + + /* Now we made sure the dword does not contain the character we are + looking for. But because we deal with strings we have to check + for the end of string before testing the next dword. */ + + xorl %edx, %ecx /* restore original dword without reload */ + movl $0xfefefeff, %edi /* magic value */ + addl %ecx, %edi /* add the magic value to the word. We get + carry bits reported for each byte which + is *not* 0 */ + jnc L(71) /* highest byte is NUL => return NULL */ + xorl %ecx, %edi /* (word+magic)^word */ + orl $0xfefefeff, %edi /* set all non-carry bits */ + incl %edi /* add 1: if one carry bit was *not* set + the addition will not result in 0. */ + jnz L(71) /* found NUL => return NULL */ + + movl 4(%eax), %ecx /* get word (= 4 bytes) in question */ + xorl %edx, %ecx /* XOR with word c|c|c|c => bytes of str == c + are now 0 */ + movl $0xfefefeff, %edi /* magic value */ + addl %ecx, %edi /* add the magic value to the word. We get + carry bits reported for each byte which + is *not* C */ + jnc L(71) /* highest byte is C => return pointer */ + xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ + orl $0xfefefeff, %edi /* set all non-carry bits */ + incl %edi /* add 1: if one carry bit was *not* set + the addition will not result in 0. */ + jnz L(71) /* found it => return pointer */ + xorl %edx, %ecx /* restore original dword without reload */ + movl $0xfefefeff, %edi /* magic value */ + addl %ecx, %edi /* add the magic value to the word. We get + carry bits reported for each byte which + is *not* 0 */ + jnc L(71) /* highest byte is NUL => return NULL */ + xorl %ecx, %edi /* (word+magic)^word */ + orl $0xfefefeff, %edi /* set all non-carry bits */ + incl %edi /* add 1: if one carry bit was *not* set + the addition will not result in 0. */ + jnz L(71) /* found NUL => return NULL */ + + movl 8(%eax), %ecx /* get word (= 4 bytes) in question */ + xorl %edx, %ecx /* XOR with word c|c|c|c => bytes of str == c + are now 0 */ + movl $0xfefefeff, %edi /* magic value */ + addl %ecx, %edi /* add the magic value to the word. We get + carry bits reported for each byte which + is *not* C */ + jnc L(72) /* highest byte is C => return pointer */ + xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ + orl $0xfefefeff, %edi /* set all non-carry bits */ + incl %edi /* add 1: if one carry bit was *not* set + the addition will not result in 0. */ + jnz L(72) /* found it => return pointer */ + xorl %edx, %ecx /* restore original dword without reload */ + movl $0xfefefeff, %edi /* magic value */ + addl %ecx, %edi /* add the magic value to the word. We get + carry bits reported for each byte which + is *not* 0 */ + jnc L(72) /* highest byte is NUL => return NULL */ + xorl %ecx, %edi /* (word+magic)^word */ + orl $0xfefefeff, %edi /* set all non-carry bits */ + incl %edi /* add 1: if one carry bit was *not* set + the addition will not result in 0. */ + jnz L(72) /* found NUL => return NULL */ + + movl 12(%eax), %ecx /* get word (= 4 bytes) in question */ + xorl %edx, %ecx /* XOR with word c|c|c|c => bytes of str == c + are now 0 */ + movl $0xfefefeff, %edi /* magic value */ + addl %ecx, %edi /* add the magic value to the word. We get + carry bits reported for each byte which + is *not* C */ + jnc L(73) /* highest byte is C => return pointer */ + xorl %ecx, %edi /* ((word^charmask)+magic)^(word^charmask) */ + orl $0xfefefeff, %edi /* set all non-carry bits */ + incl %edi /* add 1: if one carry bit was *not* set + the addition will not result in 0. */ + jnz L(73) /* found it => return pointer */ + xorl %edx, %ecx /* restore original dword without reload */ + movl $0xfefefeff, %edi /* magic value */ + addl %ecx, %edi /* add the magic value to the word. We get + carry bits reported for each byte which + is *not* 0 */ + jnc L(73) /* highest byte is NUL => return NULL */ + xorl %ecx, %edi /* (word+magic)^word */ + orl $0xfefefeff, %edi /* set all non-carry bits */ + incl %edi /* add 1: if one carry bit was *not* set + the addition will not result in 0. */ + jz L(1) /* no NUL found => restart loop */ + +L(73): addl $4, %eax /* adjust pointer */ +L(72): addl $4, %eax +L(71): addl $4, %eax + + /* We now scan for the byte in which the character was matched. + But we have to take care of the case that a NUL char is + found before this in the dword. */ + +L(7): testb %cl, %cl /* is first byte C? */ + jz L(6) /* yes => return pointer */ + cmpb %dl, %cl /* is first byte NUL? */ + je L(6) /* yes => return NULL */ + incl %eax /* it's not in the first byte */ + + testb %ch, %ch /* is second byte C? */ + jz L(6) /* yes => return pointer */ + cmpb %dl, %ch /* is second byte NUL? */ + je L(6) /* yes => return NULL? */ + incl %eax /* it's not in the second byte */ + + shrl $16, %ecx /* make upper byte accessible */ + testb %cl, %cl /* is third byte C? */ + jz L(6) /* yes => return pointer */ + cmpb %dl, %cl /* is third byte NUL? */ + je L(6) /* yes => return NULL */ + + /* It must be in the fourth byte and it cannot be NUL. */ + incl %eax + +L(6): popl %edi /* restore saved register content */ + + ret +END (__strchrnul) + +weak_alias (__strchrnul, strchrnul) |