diff options
Diffstat (limited to 'patches/glibc/2.9/210-2.9-strlen-hack.patch')
| -rw-r--r-- | patches/glibc/2.9/210-2.9-strlen-hack.patch | 109 |
1 files changed, 0 insertions, 109 deletions
diff --git a/patches/glibc/2.9/210-2.9-strlen-hack.patch b/patches/glibc/2.9/210-2.9-strlen-hack.patch deleted file mode 100644 index 6071724..0000000 --- a/patches/glibc/2.9/210-2.9-strlen-hack.patch +++ /dev/null @@ -1,109 +0,0 @@ -Original patch from: gentoo/src/patchsets/glibc/2.9/1020_all_glibc-2.9-strlen-hack.patch - --= BEGIN original header =- -http://sourceware.org/bugzilla/show_bug.cgi?id=5807 -http://www.cl.cam.ac.uk/~am21/progtricks.html - --= END original header =- - -diff -durN glibc-2_9.orig/string/strlen.c glibc-2_9/string/strlen.c ---- glibc-2_9.orig/string/strlen.c 2005-12-14 12:09:07.000000000 +0100 -+++ glibc-2_9/string/strlen.c 2009-02-02 22:00:51.000000000 +0100 -@@ -32,7 +32,7 @@ - { - const char *char_ptr; - const unsigned long int *longword_ptr; -- unsigned long int longword, magic_bits, himagic, lomagic; -+ unsigned long int longword, himagic, lomagic; - - /* Handle the first few characters by reading one character at a time. - Do this until CHAR_PTR is aligned on a longword boundary. */ -@@ -42,28 +42,14 @@ - if (*char_ptr == '\0') - return char_ptr - str; - -- /* All these elucidatory comments refer to 4-byte longwords, -- but the theory applies equally well to 8-byte longwords. */ -- - longword_ptr = (unsigned long int *) char_ptr; - -- /* Bits 31, 24, 16, and 8 of this number are zero. Call these bits -- the "holes." Note that there is a hole just to the left of -- each byte, with an extra at the end: -- -- bits: 01111110 11111110 11111110 11111111 -- bytes: AAAAAAAA BBBBBBBB CCCCCCCC DDDDDDDD -- -- The 1-bits make sure that carries propagate to the next 0-bit. -- The 0-bits provide holes for carries to fall into. */ -- magic_bits = 0x7efefeffL; - himagic = 0x80808080L; - lomagic = 0x01010101L; - if (sizeof (longword) > 4) - { - /* 64-bit version of the magic. */ - /* Do the shift in two steps to avoid a warning if long has 32 bits. */ -- magic_bits = ((0x7efefefeL << 16) << 16) | 0xfefefeffL; - himagic = ((himagic << 16) << 16) | himagic; - lomagic = ((lomagic << 16) << 16) | lomagic; - } -@@ -75,56 +61,12 @@ - if *any of the four* bytes in the longword in question are zero. */ - for (;;) - { -- /* We tentatively 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 24-30 is set, there will be a carry -- into bit 31, so all of the hole bits will be changed. -- -- The one misfire occurs when bits 24-30 are clear and bit -- 31 is set; in this case, the hole at bit 31 is not -- changed. If we had access to the processor carry flag, -- we could close this loophole by putting the fourth hole -- at bit 32! -- -- So it ignores everything except 128's, when they're aligned -- properly. */ -- - longword = *longword_ptr++; - -- if ( --#if 0 -- /* Add MAGIC_BITS to LONGWORD. */ -- (((longword + magic_bits) -- -- /* Set those bits that were unchanged by the addition. */ -- ^ ~longword) -- -- /* Look at only the hole bits. If any of the hole bits -- are unchanged, most likely one of the bytes was a -- zero. */ -- & ~magic_bits) --#else -- ((longword - lomagic) & himagic) --#endif -- != 0) -+ /* This hack taken from Alan Mycroft's HAKMEMC postings. -+ See: http://www.cl.cam.ac.uk/~am21/progtricks.html */ -+ if (((longword - lomagic) & ~longword & himagic) != 0) - { -- /* Which of the bytes was the zero? If none of them were, it was -- a misfire; continue the search. */ - - const char *cp = (const char *) (longword_ptr - 1); - |