sh: Add new optimisation to the SH4 memcpy

This optimization is based on prefetching and 64bit data transfer via FPU
(only for the little endianess)

Tests shows that:

  ----------------------------------------
  Memory bandwidth    |        Gain
                      | sh4-300 | sh4-200
  ----------------------------------------
  512 bytes to 16KiB  | ~20%    | ~25%
  from 32KiB to 16MiB | ~190%   | ~5%
  ----------------------------------------

Signed-off-by: Austin Foxley <austinf@cetoncorp.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/libc/string/sh/sh4/strcpy.S b/libc/string/sh/sh4/strcpy.S
new file mode 100644
index 000000000..0f8278017
--- /dev/null
+++ b/libc/string/sh/sh4/strcpy.S
@@ -0,0 +1,28 @@
+/* strcpy implementation for SUPERH
+ *
+ * Copyright (C) 2009 STMicroelectronics Ltd.
+ *
+ * Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+
+/*
+	char *strcpy(char *dest, const char *src);
+ */
+
+#include <sysdep.h>
+
+ENTRY(strcpy)
+	mov	r4,r2
+1:
+	mov.b	@r5+,r1
+	tst	r1,r1
+	mov.b	r1,@r2
+	bf/s	1b
+	 add	#1,r2
+
+	rts
+	 mov	r4,r0
+END(strcpy)
+libc_hidden_def (strcpy)