/*
 *  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 <linux/linkage.h>
#include <asm/asmmacro.h>
#include <asm/core.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).
 */

.text
ENTRY(__memset)
WEAK(memset)

        abi_entry_default
        # 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
        abi_ret_default

/*
 * 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(10f) s32i    a3, a5,  0
EX(10f) s32i    a3, a5,  4
EX(10f) s32i    a3, a5,  8
EX(10f) s32i    a3, a5, 12
        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(10f) s32i    a3, a5,  0
EX(10f) s32i    a3, a5,  4
        addi    a5, a5,  8
.L2:
        bbci.l  a4, 2, .L3
        # set 4 bytes
EX(10f) s32i    a3, a5,  0
        addi    a5, a5,  4
.L3:
        bbci.l  a4, 1, .L4
        # set 2 bytes
EX(10f) s16i    a3, a5,  0
        addi    a5, a5,  2
.L4:
        bbci.l  a4, 0, .L5
        # set 1 byte
EX(10f) s8i     a3, a5,  0
.L5:
.Lret1:
        abi_ret_default

/*
 * 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(10f) s8i     a3, a5,  0
        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(10f) s16i    a3, a5,  0
        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(10f) s8i     a3, a5, 0
        addi    a5, a5, 1
#if !XCHAL_HAVE_LOOPS
        blt     a5, a6, .Lbyteloop
#endif /* !XCHAL_HAVE_LOOPS */
.Lbytesetdone:
        abi_ret_default

ENDPROC(__memset)
EXPORT_SYMBOL(__memset)
EXPORT_SYMBOL(memset)

        .section .fixup, "ax"
        .align  4

/* We return zero if a failure occurred. */

10:
        movi    a2, 0
        abi_ret_default