--- /dev/null
+/*
+ * arch/xtensa/lib/memset.S
+ *
+ * ANSI C standard library function memset
+ * (Well, almost. .fixup code might return zero.)
+ *
+ * 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.
+ *
+ * Copyright (C) 2002 Tensilica Inc.
+ */
+
+#include <xtensa/coreasm.h>
+
+/*
+ * void *memset(void *dst, int c, size_t length)
+ *
+ * The algorithm is as follows:
+ * Create a word with c in all byte positions
+ * If the destination is aligned,
+ * do 16B chucks with a loop, and then finish up with
+ * 8B, 4B, 2B, and 1B stores conditional on the length.
+ * If destination is unaligned, align it by conditionally
+ * setting 1B and 2B and then go to aligned case.
+ * This code tries to use fall-through branches for the common
+ * case of an aligned destination (except for the branches to
+ * the alignment labels).
+ */
+
+/* Load or store instructions that may cause exceptions use the EX macro. */
+
+#define EX(insn,reg1,reg2,offset,handler) \
+9: insn reg1, reg2, offset; \
+ .section __ex_table, "a"; \
+ .word 9b, handler; \
+ .previous
+
+
+.text
+.align 4
+.global memset
+.type memset,@function
+memset:
+ entry sp, 16 # minimal stack frame
+ # a2/ dst, a3/ c, a4/ length
+ extui a3, a3, 0, 8 # mask to just 8 bits
+ slli a7, a3, 8 # duplicate character in all bytes of word
+ or a3, a3, a7 # ...
+ slli a7, a3, 16 # ...
+ or a3, a3, a7 # ...
+ mov a5, a2 # copy dst so that a2 is return value
+ movi a6, 3 # for alignment tests
+ bany a2, a6, .Ldstunaligned # if dst is unaligned
+.L0: # return here from .Ldstunaligned when dst is aligned
+ srli a7, a4, 4 # number of loop iterations with 16B
+ # per iteration
+ bnez a4, .Laligned
+ retw
+
+/*
+ * Destination is word-aligned.
+ */
+ # set 16 bytes per iteration for word-aligned dst
+ .align 4 # 1 mod 4 alignment for LOOPNEZ
+ .byte 0 # (0 mod 4 alignment for LBEG)
+.Laligned:
+#if XCHAL_HAVE_LOOPS
+ loopnez a7, .Loop1done
+#else /* !XCHAL_HAVE_LOOPS */
+ beqz a7, .Loop1done
+ slli a6, a7, 4
+ add a6, a6, a5 # a6 = end of last 16B chunk
+#endif /* !XCHAL_HAVE_LOOPS */
+.Loop1:
+ EX(s32i, a3, a5, 0, memset_fixup)
+ EX(s32i, a3, a5, 4, memset_fixup)
+ EX(s32i, a3, a5, 8, memset_fixup)
+ EX(s32i, a3, a5, 12, memset_fixup)
+ addi a5, a5, 16
+#if !XCHAL_HAVE_LOOPS
+ blt a5, a6, .Loop1
+#endif /* !XCHAL_HAVE_LOOPS */
+.Loop1done:
+ bbci.l a4, 3, .L2
+ # set 8 bytes
+ EX(s32i, a3, a5, 0, memset_fixup)
+ EX(s32i, a3, a5, 4, memset_fixup)
+ addi a5, a5, 8
+.L2:
+ bbci.l a4, 2, .L3
+ # set 4 bytes
+ EX(s32i, a3, a5, 0, memset_fixup)
+ addi a5, a5, 4
+.L3:
+ bbci.l a4, 1, .L4
+ # set 2 bytes
+ EX(s16i, a3, a5, 0, memset_fixup)
+ addi a5, a5, 2
+.L4:
+ bbci.l a4, 0, .L5
+ # set 1 byte
+ EX(s8i, a3, a5, 0, memset_fixup)
+.L5:
+.Lret1:
+ retw
+
+/*
+ * Destination is unaligned
+ */
+
+.Ldstunaligned:
+ bltui a4, 8, .Lbyteset # do short copies byte by byte
+ bbci.l a5, 0, .L20 # branch if dst alignment half-aligned
+ # dst is only byte aligned
+ # set 1 byte
+ EX(s8i, a3, a5, 0, memset_fixup)
+ addi a5, a5, 1
+ addi a4, a4, -1
+ # now retest if dst aligned
+ bbci.l a5, 1, .L0 # if now aligned, return to main algorithm
+.L20:
+ # dst half-aligned
+ # set 2 bytes
+ EX(s16i, a3, a5, 0, memset_fixup)
+ addi a5, a5, 2
+ addi a4, a4, -2
+ j .L0 # dst is now aligned, return to main algorithm
+
+/*
+ * Byte by byte set
+ */
+ .align 4
+ .byte 0 # 1 mod 4 alignment for LOOPNEZ
+ # (0 mod 4 alignment for LBEG)
+.Lbyteset:
+#if XCHAL_HAVE_LOOPS
+ loopnez a4, .Lbytesetdone
+#else /* !XCHAL_HAVE_LOOPS */
+ beqz a4, .Lbytesetdone
+ add a6, a5, a4 # a6 = ending address
+#endif /* !XCHAL_HAVE_LOOPS */
+.Lbyteloop:
+ EX(s8i, a3, a5, 0, memset_fixup)
+ addi a5, a5, 1
+#if !XCHAL_HAVE_LOOPS
+ blt a5, a6, .Lbyteloop
+#endif /* !XCHAL_HAVE_LOOPS */
+.Lbytesetdone:
+ retw
+
+
+ .section .fixup, "ax"
+ .align 4
+
+/* We return zero if a failure occurred. */
+
+memset_fixup:
+ movi a2, 0
+ retw
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