1 files changed, 67 insertions, 0 deletions

diff --git a/arch/tile/lib/strchr_64.c b/arch/tile/lib/strchr_64.c
new file mode 100644
index 000000000000..617a9273aaa8
--- /dev/null
+++ b/arch/tile/lib/strchr_64.c
@@ -0,0 +1,67 @@
+/*
+ * Copyright 2011 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program 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, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+#undef strchr
+
+char *strchr(const char *s, int c)
+{
+        int z, g;
+
+        /* Get an aligned pointer. */
+        const uintptr_t s_int = (uintptr_t) s;
+        const uint64_t *p = (const uint64_t *)(s_int & -8);
+
+        /* Create eight copies of the byte for which we are looking. */
+        const uint64_t goal = 0x0101010101010101ULL * (uint8_t) c;
+
+        /* Read the first aligned word, but force bytes before the string to
+         * match neither zero nor goal (we make sure the high bit of each
+         * byte is 1, and the low 7 bits are all the opposite of the goal
+         * byte).
+         *
+         * Note that this shift count expression works because we know shift
+         * counts are taken mod 64.
+         */
+        const uint64_t before_mask = (1ULL << (s_int << 3)) - 1;
+        uint64_t v = (*p | before_mask) ^
+                (goal & __insn_v1shrsi(before_mask, 1));
+
+        uint64_t zero_matches, goal_matches;
+        while (1) {
+                /* Look for a terminating '\0'. */
+                zero_matches = __insn_v1cmpeqi(v, 0);
+
+                /* Look for the goal byte. */
+                goal_matches = __insn_v1cmpeq(v, goal);
+
+                if (__builtin_expect((zero_matches | goal_matches) != 0, 0))
+                        break;
+
+                v = *++p;
+        }
+
+        z = __insn_ctz(zero_matches);
+        g = __insn_ctz(goal_matches);
+
+        /* If we found c before '\0' we got a match. Note that if c == '\0'
+         * then g == z, and we correctly return the address of the '\0'
+         * rather than NULL.
+         */
+        return (g <= z) ? ((char *)p) + (g >> 3) : NULL;
+}
+EXPORT_SYMBOL(strchr);