1 files changed, 145 insertions, 0 deletions

diff --git a/arch/tile/lib/memset_64.c b/arch/tile/lib/memset_64.c
new file mode 100644
index 000000000000..3873085711d5
--- /dev/null
+++ b/arch/tile/lib/memset_64.c
@@ -0,0 +1,145 @@
+/*
+ * 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 <arch/chip.h>
+
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+#undef memset
+
+void *memset(void *s, int c, size_t n)
+{
+        uint64_t *out64;
+        int n64, to_align64;
+        uint64_t v64;
+        uint8_t *out8 = s;
+
+        /* Experimentation shows that a trivial tight loop is a win up until
+         * around a size of 20, where writing a word at a time starts to win.
+         */
+#define BYTE_CUTOFF 20
+
+#if BYTE_CUTOFF < 7
+        /* This must be at least at least this big, or some code later
+         * on doesn't work.
+         */
+#error "BYTE_CUTOFF is too small"
+#endif
+
+        if (n < BYTE_CUTOFF) {
+                /* Strangely, this turns out to be the tightest way to
+                 * write this loop.
+                 */
+                if (n != 0) {
+                        do {
+                                /* Strangely, combining these into one line
+                                 * performs worse.
+                                 */
+                                *out8 = c;
+                                out8++;
+                        } while (--n != 0);
+                }
+
+                return s;
+        }
+
+        /* Align 'out8'. We know n >= 7 so this won't write past the end. */
+        while (((uintptr_t) out8 & 7) != 0) {
+                *out8++ = c;
+                --n;
+        }
+
+        /* Align 'n'. */
+        while (n & 7)
+                out8[--n] = c;
+
+        out64 = (uint64_t *) out8;
+        n64 = n >> 3;
+
+        /* Tile input byte out to 64 bits. */
+        /* KLUDGE */
+        v64 = 0x0101010101010101ULL * (uint8_t)c;
+
+        /* This must be at least 8 or the following loop doesn't work. */
+#define CACHE_LINE_SIZE_IN_DOUBLEWORDS (CHIP_L2_LINE_SIZE() / 8)
+
+        /* Determine how many words we need to emit before the 'out32'
+         * pointer becomes aligned modulo the cache line size.
+         */
+        to_align64 = (-((uintptr_t)out64 >> 3)) &
+                (CACHE_LINE_SIZE_IN_DOUBLEWORDS - 1);
+
+        /* Only bother aligning and using wh64 if there is at least
+         * one full cache line to process.  This check also prevents
+         * overrunning the end of the buffer with alignment words.
+         */
+        if (to_align64 <= n64 - CACHE_LINE_SIZE_IN_DOUBLEWORDS) {
+                int lines_left;
+
+                /* Align out64 mod the cache line size so we can use wh64. */
+                n64 -= to_align64;
+                for (; to_align64 != 0; to_align64--) {
+                        *out64 = v64;
+                        out64++;
+                }
+
+                /* Use unsigned divide to turn this into a right shift. */
+                lines_left = (unsigned)n64 / CACHE_LINE_SIZE_IN_DOUBLEWORDS;
+
+                do {
+                        /* Only wh64 a few lines at a time, so we don't
+                         * exceed the maximum number of victim lines.
+                         */
+                        int x = ((lines_left < CHIP_MAX_OUTSTANDING_VICTIMS())
+                                  ? lines_left
+                                  : CHIP_MAX_OUTSTANDING_VICTIMS());
+                        uint64_t *wh = out64;
+                        int i = x;
+                        int j;
+
+                        lines_left -= x;
+
+                        do {
+                                __insn_wh64(wh);
+                                wh += CACHE_LINE_SIZE_IN_DOUBLEWORDS;
+                        } while (--i);
+
+                        for (j = x * (CACHE_LINE_SIZE_IN_DOUBLEWORDS / 4);
+                             j != 0; j--) {
+                                *out64++ = v64;
+                                *out64++ = v64;
+                                *out64++ = v64;
+                                *out64++ = v64;
+                        }
+                } while (lines_left != 0);
+
+                /* We processed all full lines above, so only this many
+                 * words remain to be processed.
+                 */
+                n64 &= CACHE_LINE_SIZE_IN_DOUBLEWORDS - 1;
+        }
+
+        /* Now handle any leftover values. */
+        if (n64 != 0) {
+                do {
+                        *out64 = v64;
+                        out64++;
+                } while (--n64 != 0);
+        }
+
+        return s;
+}
+EXPORT_SYMBOL(memset);