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-rw-r--r--arch/xtensa/lib/strnlen_user.S141
1 files changed, 141 insertions, 0 deletions
diff --git a/arch/xtensa/lib/strnlen_user.S b/arch/xtensa/lib/strnlen_user.S
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+++ b/arch/xtensa/lib/strnlen_user.S
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+/*
+ * arch/xtensa/lib/strnlen_user.S
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of
+ * this archive for more details.
+ *
+ * Returns strnlen, including trailing zero terminator.
+ * Zero indicates error.
+ *
+ * Copyright (C) 2002 Tensilica Inc.
+ */
+
+#include <linux/linkage.h>
+#include <asm/asmmacro.h>
+#include <asm/core.h>
+
+/*
+ * size_t __strnlen_user(const char *s, size_t len)
+ */
+
+#ifdef __XTENSA_EB__
+# define MASK0 0xff000000
+# define MASK1 0x00ff0000
+# define MASK2 0x0000ff00
+# define MASK3 0x000000ff
+#else
+# define MASK0 0x000000ff
+# define MASK1 0x0000ff00
+# define MASK2 0x00ff0000
+# define MASK3 0xff000000
+#endif
+
+# Register use:
+# a2/ src
+# a3/ len
+# a4/ tmp
+# a5/ mask0
+# a6/ mask1
+# a7/ mask2
+# a8/ mask3
+# a9/ tmp
+# a10/ tmp
+
+.text
+ENTRY(__strnlen_user)
+
+ abi_entry_default
+ # a2/ s, a3/ len
+ addi a4, a2, -4 # because we overincrement at the end;
+ # we compensate with load offsets of 4
+ movi a5, MASK0 # mask for byte 0
+ movi a6, MASK1 # mask for byte 1
+ movi a7, MASK2 # mask for byte 2
+ movi a8, MASK3 # mask for byte 3
+ bbsi.l a2, 0, .L1mod2 # if only 8-bit aligned
+ bbsi.l a2, 1, .L2mod4 # if only 16-bit aligned
+
+/*
+ * String is word-aligned.
+ */
+.Laligned:
+ srli a10, a3, 2 # number of loop iterations with 4B per loop
+#if XCHAL_HAVE_LOOPS
+ loopnez a10, .Ldone
+#else
+ beqz a10, .Ldone
+ slli a10, a10, 2
+ add a10, a10, a4 # a10 = end of last 4B chunk
+#endif /* XCHAL_HAVE_LOOPS */
+.Loop:
+EX(10f) l32i a9, a4, 4 # get next word of string
+ addi a4, a4, 4 # advance string pointer
+ bnone a9, a5, .Lz0 # if byte 0 is zero
+ bnone a9, a6, .Lz1 # if byte 1 is zero
+ bnone a9, a7, .Lz2 # if byte 2 is zero
+ bnone a9, a8, .Lz3 # if byte 3 is zero
+#if !XCHAL_HAVE_LOOPS
+ blt a4, a10, .Loop
+#endif
+
+.Ldone:
+EX(10f) l32i a9, a4, 4 # load 4 bytes for remaining checks
+
+ bbci.l a3, 1, .L100
+ # check two more bytes (bytes 0, 1 of word)
+ addi a4, a4, 2 # advance string pointer
+ bnone a9, a5, .Lz0 # if byte 0 is zero
+ bnone a9, a6, .Lz1 # if byte 1 is zero
+.L100:
+ bbci.l a3, 0, .L101
+ # check one more byte (byte 2 of word)
+ # Actually, we don't need to check. Zero or nonzero, we'll add one.
+ # Do not add an extra one for the NULL terminator since we have
+ # exhausted the original len parameter.
+ addi a4, a4, 1 # advance string pointer
+.L101:
+ sub a2, a4, a2 # compute length
+ abi_ret_default
+
+# NOTE that in several places below, we point to the byte just after
+# the zero byte in order to include the NULL terminator in the count.
+
+.Lz3: # byte 3 is zero
+ addi a4, a4, 3 # point to zero byte
+.Lz0: # byte 0 is zero
+ addi a4, a4, 1 # point just beyond zero byte
+ sub a2, a4, a2 # subtract to get length
+ abi_ret_default
+.Lz1: # byte 1 is zero
+ addi a4, a4, 1+1 # point just beyond zero byte
+ sub a2, a4, a2 # subtract to get length
+ abi_ret_default
+.Lz2: # byte 2 is zero
+ addi a4, a4, 2+1 # point just beyond zero byte
+ sub a2, a4, a2 # subtract to get length
+ abi_ret_default
+
+.L1mod2: # address is odd
+EX(10f) l8ui a9, a4, 4 # get byte 0
+ addi a4, a4, 1 # advance string pointer
+ beqz a9, .Lz3 # if byte 0 is zero
+ bbci.l a4, 1, .Laligned # if string pointer is now word-aligned
+
+.L2mod4: # address is 2 mod 4
+ addi a4, a4, 2 # advance ptr for aligned access
+EX(10f) l32i a9, a4, 0 # get word with first two bytes of string
+ bnone a9, a7, .Lz2 # if byte 2 (of word, not string) is zero
+ bany a9, a8, .Laligned # if byte 3 (of word, not string) is nonzero
+ # byte 3 is zero
+ addi a4, a4, 3+1 # point just beyond zero byte
+ sub a2, a4, a2 # subtract to get length
+ abi_ret_default
+
+ENDPROC(__strnlen_user)
+
+ .section .fixup, "ax"
+ .align 4
+10:
+ movi a2, 0
+ abi_ret_default