1 files changed, 143 insertions, 0 deletions
diff --git a/arch/tile/lib/memset_32.c b/arch/tile/lib/memset_32.c
new file mode 100644
index 000000000..2042bfe65
--- /dev/null
+++ b/arch/tile/lib/memset_32.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright 2010 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>
+#include <arch/chip.h>
+
+void *memset(void *s, int c, size_t n)
+{
+	uint32_t *out32;
+	int n32;
+	uint32_t v16, v32;
+	uint8_t *out8 = s;
+	int to_align32;
+
+	/* 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 < 3
+	/* 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 >= 3 so this won't write past the end. */
+	while (((uintptr_t) out8 & 3) != 0) {
+		*out8++ = c;
+		--n;
+	}
+
+	/* Align 'n'. */
+	while (n & 3)
+		out8[--n] = c;
+
+	out32 = (uint32_t *) out8;
+	n32 = n >> 2;
+
+	/* Tile input byte out to 32 bits. */
+	v16 = __insn_intlb(c, c);
+	v32 = __insn_intlh(v16, v16);
+
+	/* This must be at least 8 or the following loop doesn't work. */
+#define CACHE_LINE_SIZE_IN_WORDS (CHIP_L2_LINE_SIZE() / 4)
+
+	/* Determine how many words we need to emit before the 'out32'
+	 * pointer becomes aligned modulo the cache line size.
+	 */
+	to_align32 =
+		(-((uintptr_t)out32 >> 2)) & (CACHE_LINE_SIZE_IN_WORDS - 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_align32 <= n32 - CACHE_LINE_SIZE_IN_WORDS) {
+		int lines_left;
+
+		/* Align out32 mod the cache line size so we can use wh64. */
+		n32 -= to_align32;
+		for (; to_align32 != 0; to_align32--) {
+			*out32 = v32;
+			out32++;
+		}
+
+		/* Use unsigned divide to turn this into a right shift. */
+		lines_left = (unsigned)n32 / CACHE_LINE_SIZE_IN_WORDS;
+
+		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());
+			uint32_t *wh = out32;
+			int i = x;
+			int j;
+
+			lines_left -= x;
+
+			do {
+				__insn_wh64(wh);
+				wh += CACHE_LINE_SIZE_IN_WORDS;
+			} while (--i);
+
+			for (j = x * (CACHE_LINE_SIZE_IN_WORDS / 4);
+			     j != 0; j--) {
+				*out32++ = v32;
+				*out32++ = v32;
+				*out32++ = v32;
+				*out32++ = v32;
+			}
+		} while (lines_left != 0);
+
+		/* We processed all full lines above, so only this many
+		 * words remain to be processed.
+		 */
+		n32 &= CACHE_LINE_SIZE_IN_WORDS - 1;
+	}
+
+	/* Now handle any leftover values. */
+	if (n32 != 0) {
+		do {
+			*out32 = v32;
+			out32++;
+		} while (--n32 != 0);
+	}
+
+	return s;
+}
+EXPORT_SYMBOL(memset);