--- /dev/null
+/* Copyright (C) 1996 Free Software Foundation, Inc.
+ Contributed by David Mosberger (davidm@cs.arizona.edu).
+
+This file is part of the GNU C Library.
+
+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., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+/* Finds characters in a memory area. Optimized for the Alpha
+architecture:
+
+ - memory accessed as aligned quadwords only
+ - uses cmpbge to compare 8 bytes in parallel
+ - does binary search to find 0 byte in last
+ quadword (HAKMEM needed 12 instructions to
+ do this instead of the 9 instructions that
+ binary search needs).
+
+For correctness consider that:
+
+ - only minimum number of quadwords may be accessed
+ - the third argument is an unsigned long
+*/
+
+#include <sysdep.h>
+#ifdef __linux__
+# include <alpha/regdef.h>
+#else
+#include <regdef.h>
+#endif
+
+ .set noreorder
+ .set noat
+
+ENTRY(memchr)
+ beq a2, not_found
+ ldq_u t0, 0(a0) # load first quadword (a0 may be misaligned)
+ addq a0, a2, t4
+ and a1, 0xff, a1 # a1 = 00000000000000ch
+ ldq_u t5, -1(t4)
+ sll a1, 8, t1 # t1 = 000000000000ch00
+ cmpult a2, 9, t3
+ or t1, a1, a1 # a1 = 000000000000chch
+ sll a1, 16, t1 # t1 = 00000000chch0000
+ lda t2, -1(zero)
+ or t1, a1, a1 # a1 = 00000000chchchch
+ sll a1, 32, t1 # t1 = chchchch00000000
+ extql t0, a0, t6
+ or t1, a1, a1 # a1 = chchchchchchchch
+
+ beq t3, first_quad
+
+ extqh t5, a0, t5
+ mov a0, v0
+ or t6, t5, t0 # t0 = quadword starting at a0
+
+ #
+ # Deal with the case where at most 8 bytes remain to be searched
+ # in t0. E.g.:
+ # a2 = 6
+ # t0 = ????c6c5c4c3c2c1
+last_quad:
+ negq a2, t5
+ srl t2, t5, t5 # t5 = mask of a2 bits set
+ xor a1, t0, t0
+ cmpbge zero, t0, t1
+ and t1, t5, t1
+ beq t1, not_found
+
+found_it:
+ # now, determine which byte matched:
+ negq t1, t2
+ and t1, t2, t1
+
+ and t1, 0x0f, t0
+ addq v0, 4, t2
+ cmoveq t0, t2, v0
+
+ and t1, 0x33, t0
+ addq v0, 2, t2
+ cmoveq t0, t2, v0
+
+ and t1, 0x55, t0
+ addq v0, 1, t2
+ cmoveq t0, t2, v0
+
+done: ret
+
+
+ #
+ # Deal with the case where a2 > 8 bytes remain to be
+ # searched. a0 may not be aligned.
+ #
+first_quad:
+ andnot a0, 0x7, v0
+ insqh t2, a0, t1 # t1 = 0000ffffffffffff (a0<0:2> ff bytes)
+ xor t0, a1, t0
+ or t0, t1, t0 # t0 = ====ffffffffffff
+ cmpbge zero, t0, t1
+ bne t1, found_it
+
+ /* at least one byte left to process */
+
+ ldq t0, 8(v0)
+ addq v0, 8, v0
+ /*
+ * Make a2 point to last quad to be accessed (the
+ * last quad may or may not be partial).
+ */
+ subq t4, 1, a2
+ andnot a2, 0x7, a2
+ cmpult v0, a2, t1
+ beq t1, final
+
+ /* at least two quads remain to be accessed */
+
+ subq a2, v0, t3 # t3 <- number of quads to be processed in loop
+ and t3, 8, t3 # odd number of quads?
+ bne t3, odd_quad_count
+
+ /* at least three quads remain to be accessed */
+
+ mov t0, t3 # move prefetched value into correct register
+
+ .align 3
+unrolled_loop:
+ ldq t0, 8(v0) # prefetch t0
+ xor a1, t3, t1
+ cmpbge zero, t1, t1
+ bne t1, found_it
+
+ addq v0, 8, v0
+odd_quad_count:
+ xor a1, t0, t1
+ ldq t3, 8(v0) # prefetch t3
+ cmpbge zero, t1, t1
+ bne t1, found_it
+
+ addq v0, 8, v0
+ cmpult v0, a2, t5
+ bne t5, unrolled_loop
+
+ mov t3, t0 # move prefetched value into t0
+final: subq t4, v0, a2 # a2 <- number of bytes left to do
+ bne a2, last_quad
+
+not_found:
+ mov zero, v0
+ ret
+
+ .end memchr
+++ /dev/null
-/* Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
-
-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., 675 Mass Ave,
-Cambridge, MA 02139, USA. */
-
-#include <string.h>
-
-/* Search no more than N bytes of S for C. */
-
-void *
-memchr (const void *s, int c, size_t n)
-{
- const char *char_ptr;
- const unsigned long int *longword_ptr;
- unsigned long int charmask;
- size_t x;
-
- c = (unsigned char) c;
-
- /* Handle the first few characters by reading one character at a time.
- Do this until STR is aligned on a 8-byte border. */
- for (char_ptr = s; n > 0 && ((unsigned long int) char_ptr & 7) != 0;
- --n, ++char_ptr)
- if (*char_ptr == c)
- return (void *) char_ptr;
-
- if (n == (size_t)0)
- return NULL;
-
- x = n;
-
- longword_ptr = (unsigned long int *) char_ptr;
-
- /* Set up a longword, each of whose bytes is C. */
- charmask = c | (c << 8);
- charmask |= charmask << 16;
- charmask |= charmask << 32;
-
- for (;;)
- {
- const unsigned long int longword = *longword_ptr++;
- int ge, le;
-
- if (x < 4)
- x = (size_t) 0;
- else
- x -= 4;
-
- /* Set bits in GE if bytes in CHARMASK are >= bytes in LONGWORD. */
- asm ("cmpbge %1, %2, %0" : "=r" (ge) : "r" (charmask), "r" (longword));
-
- /* Set bits in LE if bytes in CHARMASK are <= bytes in LONGWORD. */
- asm ("cmpbge %2, %1, %0" : "=r" (le) : "r" (charmask), "r" (longword));
-
- /* Bytes that are both <= and >= are == to C. */
- if (ge & le)
- {
- /* Which of the bytes was the C? */
-
- unsigned char *cp = (unsigned char *) (longword_ptr - 1);
- int i;
-
- for (i = 0; i < 7; i++)
- if (cp[i] == c)
- return &cp[i];
- return &cp[7];
- }
-
- if (x == (size_t)0)
- break;
- }
-
- return NULL;
-}
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