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authorAustin Foxley <austinf@cetoncorp.com>2009-11-22 12:17:38 -0800
committerAustin Foxley <austinf@cetoncorp.com>2009-11-22 12:17:38 -0800
commit5c9ef58ec4bcb2def9e30f0b156f9cfcb1d0d163 (patch)
treef8f889678b653d5275c285a037b9b43f27a91192 /libc/string/sh/sh4/strncpy.S
parentf757db2d319ccc5f7034165046fb2bb58901afb1 (diff)
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>
Diffstat (limited to 'libc/string/sh/sh4/strncpy.S')
-rw-r--r--libc/string/sh/sh4/strncpy.S43
1 files changed, 43 insertions, 0 deletions
diff --git a/libc/string/sh/sh4/strncpy.S b/libc/string/sh/sh4/strncpy.S
new file mode 100644
index 000000000..8a16f39d4
--- /dev/null
+++ b/libc/string/sh/sh4/strncpy.S
@@ -0,0 +1,43 @@
+/* strncpy 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 *strncpy(char *dest, const char *src, size_t n);
+ */
+
+#include <sysdep.h>
+
+ENTRY(strncpy)
+ mov #0,r0
+ bra 2f
+ mov r4,r2
+1:
+ mov.b r1,@(r0,r2)
+ add #1,r0
+2:
+ cmp/hs r6,r0
+ bt 5f
+ mov.b @(r0,r5),r1
+ tst r1,r1
+ bf/s 1b
+ cmp/hs r6,r0
+ bra 4f
+ nop
+3:
+ mov.b r1,@(r0,r2)
+ add #1,r0
+ cmp/hs r6,r0
+4:
+ bf/s 3b
+ mov #0,r1
+5:
+ rts
+ mov r2,r0
+END(strncpy)
+libc_hidden_def(strncpy)