/*
 * arch/xtensa/lib/hal/memcopy.S -- Core HAL library functions
 * xthal_memcpy and xthal_bcopy
 *
 * 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 - 2012 Tensilica Inc.
 */

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

/*
 * void *memcpy(void *dst, const void *src, size_t len);
 *
 * This function is intended to do the same thing as the standard
 * library function memcpy() for most cases.
 * However, where the source and/or destination references
 * an instruction RAM or ROM or a data RAM or ROM, that
 * source and/or destination will always be accessed with
 * 32-bit load and store instructions (as required for these
 * types of devices).
 *
 * !!!!!!!  XTFIXME:
 * !!!!!!!  Handling of IRAM/IROM has not yet
 * !!!!!!!  been implemented.
 *
 * The (general case) algorithm is as follows:
 *   If destination is unaligned, align it by conditionally
 *     copying 1 and 2 bytes.
 *   If source is aligned,
 *     do 16 bytes with a loop, and then finish up with
 *     8, 4, 2, and 1 byte copies conditional on the length;
 *   else (if source is unaligned),
 *     do the same, but use SRC to align the source data.
 *   This code tries to use fall-through branches for the common
 *     case of aligned source and destination and multiple
 *     of 4 (or 8) length.
 *
 * Register use:
 *      a0/ return address
 *      a1/ stack pointer
 *      a2/ return value
 *      a3/ src
 *      a4/ length
 *      a5/ dst
 *      a6/ tmp
 *      a7/ tmp
 *      a8/ tmp
 *      a9/ tmp
 *      a10/ tmp
 *      a11/ tmp
 */

        .text

/*
 * Byte by byte copy
 */
        .align  4
        .byte   0               # 1 mod 4 alignment for LOOPNEZ
                                # (0 mod 4 alignment for LBEG)
.Lbytecopy:
#if XCHAL_HAVE_LOOPS
        loopnez a4, .Lbytecopydone
#else /* !XCHAL_HAVE_LOOPS */
        beqz    a4, .Lbytecopydone
        add     a7, a3, a4      # a7 = end address for source
#endif /* !XCHAL_HAVE_LOOPS */
.Lnextbyte:
        l8ui    a6, a3, 0
        addi    a3, a3, 1
        s8i     a6, a5, 0
        addi    a5, a5, 1
#if !XCHAL_HAVE_LOOPS
        bne     a3, a7, .Lnextbyte # continue loop if $a3:src != $a7:src_end
#endif /* !XCHAL_HAVE_LOOPS */
.Lbytecopydone:
        abi_ret_default

/*
 * Destination is unaligned
 */

        .align  4
.Ldst1mod2:     # dst is only byte aligned
        _bltui  a4, 7, .Lbytecopy       # do short copies byte by byte

        # copy 1 byte
        l8ui    a6, a3,  0
        addi    a3, a3,  1
        addi    a4, a4, -1
        s8i     a6, a5,  0
        addi    a5, a5,  1
        _bbci.l a5, 1, .Ldstaligned     # if dst is now aligned, then
                                        # return to main algorithm
.Ldst2mod4:     # dst 16-bit aligned
        # copy 2 bytes
        _bltui  a4, 6, .Lbytecopy       # do short copies byte by byte
        l8ui    a6, a3,  0
        l8ui    a7, a3,  1
        addi    a3, a3,  2
        addi    a4, a4, -2
        s8i     a6, a5,  0
        s8i     a7, a5,  1
        addi    a5, a5,  2
        j       .Ldstaligned    # dst is now aligned, return to main algorithm

ENTRY(__memcpy)
WEAK(memcpy)

        abi_entry_default
        # a2/ dst, a3/ src, a4/ len
        mov     a5, a2          # copy dst so that a2 is return value
.Lcommon:
        _bbsi.l a2, 0, .Ldst1mod2       # if dst is 1 mod 2
        _bbsi.l a2, 1, .Ldst2mod4       # if dst is 2 mod 4
.Ldstaligned:   # return here from .Ldst?mod? once dst is aligned
        srli    a7, a4, 4       # number of loop iterations with 16B
                                # per iteration
        movi    a8, 3           # if source is not aligned,
        _bany   a3, a8, .Lsrcunaligned  # then use shifting copy
        /*
         * Destination and source are word-aligned, use word copy.
         */
        # copy 16 bytes per iteration for word-aligned dst and word-aligned src
#if XCHAL_HAVE_LOOPS
        loopnez a7, .Loop1done
#else /* !XCHAL_HAVE_LOOPS */
        beqz    a7, .Loop1done
        slli    a8, a7, 4
        add     a8, a8, a3      # a8 = end of last 16B source chunk
#endif /* !XCHAL_HAVE_LOOPS */
.Loop1:
        l32i    a6, a3,  0
        l32i    a7, a3,  4
        s32i    a6, a5,  0
        l32i    a6, a3,  8
        s32i    a7, a5,  4
        l32i    a7, a3, 12
        s32i    a6, a5,  8
        addi    a3, a3, 16
        s32i    a7, a5, 12
        addi    a5, a5, 16
#if !XCHAL_HAVE_LOOPS
        bne     a3, a8, .Loop1  # continue loop if a3:src != a8:src_end
#endif /* !XCHAL_HAVE_LOOPS */
.Loop1done:
        bbci.l  a4, 3, .L2
        # copy 8 bytes
        l32i    a6, a3,  0
        l32i    a7, a3,  4
        addi    a3, a3,  8
        s32i    a6, a5,  0
        s32i    a7, a5,  4
        addi    a5, a5,  8
.L2:
        bbsi.l  a4, 2, .L3
        bbsi.l  a4, 1, .L4
        bbsi.l  a4, 0, .L5
        abi_ret_default
.L3:
        # copy 4 bytes
        l32i    a6, a3,  0
        addi    a3, a3,  4
        s32i    a6, a5,  0
        addi    a5, a5,  4
        bbsi.l  a4, 1, .L4
        bbsi.l  a4, 0, .L5
        abi_ret_default
.L4:
        # copy 2 bytes
        l16ui   a6, a3,  0
        addi    a3, a3,  2
        s16i    a6, a5,  0
        addi    a5, a5,  2
        bbsi.l  a4, 0, .L5
        abi_ret_default
.L5:
        # copy 1 byte
        l8ui    a6, a3,  0
        s8i     a6, a5,  0
        abi_ret_default

/*
 * Destination is aligned, Source is unaligned
 */

        .align  4
.Lsrcunaligned:
        _beqz   a4, .Ldone      # avoid loading anything for zero-length copies
        # copy 16 bytes per iteration for word-aligned dst and unaligned src
        __ssa8  a3              # set shift amount from byte offset

/* set to 1 when running on ISS (simulator) with the
   lint or ferret client, or 0 to save a few cycles */
#define SIM_CHECKS_ALIGNMENT    1
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
        and     a11, a3, a8     # save unalignment offset for below
        sub     a3, a3, a11     # align a3
#endif
        l32i    a6, a3, 0       # load first word
#if XCHAL_HAVE_LOOPS
        loopnez a7, .Loop2done
#else /* !XCHAL_HAVE_LOOPS */
        beqz    a7, .Loop2done
        slli    a10, a7, 4
        add     a10, a10, a3    # a10 = end of last 16B source chunk
#endif /* !XCHAL_HAVE_LOOPS */
.Loop2:
        l32i    a7, a3,  4
        l32i    a8, a3,  8
        __src_b a6, a6, a7
        s32i    a6, a5,  0
        l32i    a9, a3, 12
        __src_b a7, a7, a8
        s32i    a7, a5,  4
        l32i    a6, a3, 16
        __src_b a8, a8, a9
        s32i    a8, a5,  8
        addi    a3, a3, 16
        __src_b a9, a9, a6
        s32i    a9, a5, 12
        addi    a5, a5, 16
#if !XCHAL_HAVE_LOOPS
        bne     a3, a10, .Loop2 # continue loop if a3:src != a10:src_end
#endif /* !XCHAL_HAVE_LOOPS */
.Loop2done:
        bbci.l  a4, 3, .L12
        # copy 8 bytes
        l32i    a7, a3,  4
        l32i    a8, a3,  8
        __src_b a6, a6, a7
        s32i    a6, a5,  0
        addi    a3, a3,  8
        __src_b a7, a7, a8
        s32i    a7, a5,  4
        addi    a5, a5,  8
        mov     a6, a8
.L12:
        bbci.l  a4, 2, .L13
        # copy 4 bytes
        l32i    a7, a3,  4
        addi    a3, a3,  4
        __src_b a6, a6, a7
        s32i    a6, a5,  0
        addi    a5, a5,  4
        mov     a6, a7
.L13:
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
        add     a3, a3, a11     # readjust a3 with correct misalignment
#endif
        bbsi.l  a4, 1, .L14
        bbsi.l  a4, 0, .L15
.Ldone: abi_ret_default
.L14:
        # copy 2 bytes
        l8ui    a6, a3,  0
        l8ui    a7, a3,  1
        addi    a3, a3,  2
        s8i     a6, a5,  0
        s8i     a7, a5,  1
        addi    a5, a5,  2
        bbsi.l  a4, 0, .L15
        abi_ret_default
.L15:
        # copy 1 byte
        l8ui    a6, a3,  0
        s8i     a6, a5,  0
        abi_ret_default

ENDPROC(__memcpy)
EXPORT_SYMBOL(__memcpy)
EXPORT_SYMBOL(memcpy)

/*
 * void *memmove(void *dst, const void *src, size_t len);
 *
 * This function is intended to do the same thing as the standard
 * library function memmove() for most cases.
 * However, where the source and/or destination references
 * an instruction RAM or ROM or a data RAM or ROM, that
 * source and/or destination will always be accessed with
 * 32-bit load and store instructions (as required for these
 * types of devices).
 *
 * !!!!!!!  XTFIXME:
 * !!!!!!!  Handling of IRAM/IROM has not yet
 * !!!!!!!  been implemented.
 *
 * The (general case) algorithm is as follows:
 *   If end of source doesn't overlap destination then use memcpy.
 *   Otherwise do memcpy backwards.
 *
 * Register use:
 *      a0/ return address
 *      a1/ stack pointer
 *      a2/ return value
 *      a3/ src
 *      a4/ length
 *      a5/ dst
 *      a6/ tmp
 *      a7/ tmp
 *      a8/ tmp
 *      a9/ tmp
 *      a10/ tmp
 *      a11/ tmp
 */

/*
 * Byte by byte copy
 */
        .align  4
        .byte   0               # 1 mod 4 alignment for LOOPNEZ
                                # (0 mod 4 alignment for LBEG)
.Lbackbytecopy:
#if XCHAL_HAVE_LOOPS
        loopnez a4, .Lbackbytecopydone
#else /* !XCHAL_HAVE_LOOPS */
        beqz    a4, .Lbackbytecopydone
        sub     a7, a3, a4      # a7 = start address for source
#endif /* !XCHAL_HAVE_LOOPS */
.Lbacknextbyte:
        addi    a3, a3, -1
        l8ui    a6, a3, 0
        addi    a5, a5, -1
        s8i     a6, a5, 0
#if !XCHAL_HAVE_LOOPS
        bne     a3, a7, .Lbacknextbyte # continue loop if
                                       # $a3:src != $a7:src_start
#endif /* !XCHAL_HAVE_LOOPS */
.Lbackbytecopydone:
        abi_ret_default

/*
 * Destination is unaligned
 */

        .align  4
.Lbackdst1mod2: # dst is only byte aligned
        _bltui  a4, 7, .Lbackbytecopy   # do short copies byte by byte

        # copy 1 byte
        addi    a3, a3, -1
        l8ui    a6, a3,  0
        addi    a5, a5, -1
        s8i     a6, a5,  0
        addi    a4, a4, -1
        _bbci.l a5, 1, .Lbackdstaligned # if dst is now aligned, then
                                        # return to main algorithm
.Lbackdst2mod4: # dst 16-bit aligned
        # copy 2 bytes
        _bltui  a4, 6, .Lbackbytecopy   # do short copies byte by byte
        addi    a3, a3, -2
        l8ui    a6, a3,  0
        l8ui    a7, a3,  1
        addi    a5, a5, -2
        s8i     a6, a5,  0
        s8i     a7, a5,  1
        addi    a4, a4, -2
        j       .Lbackdstaligned        # dst is now aligned,
                                        # return to main algorithm

ENTRY(__memmove)
WEAK(memmove)

        abi_entry_default
        # a2/ dst, a3/ src, a4/ len
        mov     a5, a2          # copy dst so that a2 is return value
.Lmovecommon:
        sub     a6, a5, a3
        bgeu    a6, a4, .Lcommon

        add     a5, a5, a4
        add     a3, a3, a4

        _bbsi.l a5, 0, .Lbackdst1mod2   # if dst is 1 mod 2
        _bbsi.l a5, 1, .Lbackdst2mod4   # if dst is 2 mod 4
.Lbackdstaligned:       # return here from .Lbackdst?mod? once dst is aligned
        srli    a7, a4, 4       # number of loop iterations with 16B
                                # per iteration
        movi    a8, 3           # if source is not aligned,
        _bany   a3, a8, .Lbacksrcunaligned      # then use shifting copy
        /*
         * Destination and source are word-aligned, use word copy.
         */
        # copy 16 bytes per iteration for word-aligned dst and word-aligned src
#if XCHAL_HAVE_LOOPS
        loopnez a7, .LbackLoop1done
#else /* !XCHAL_HAVE_LOOPS */
        beqz    a7, .LbackLoop1done
        slli    a8, a7, 4
        sub     a8, a3, a8      # a8 = start of first 16B source chunk
#endif /* !XCHAL_HAVE_LOOPS */
.LbackLoop1:
        addi    a3, a3, -16
        l32i    a7, a3, 12
        l32i    a6, a3,  8
        addi    a5, a5, -16
        s32i    a7, a5, 12
        l32i    a7, a3,  4
        s32i    a6, a5,  8
        l32i    a6, a3,  0
        s32i    a7, a5,  4
        s32i    a6, a5,  0
#if !XCHAL_HAVE_LOOPS
        bne     a3, a8, .LbackLoop1  # continue loop if a3:src != a8:src_start
#endif /* !XCHAL_HAVE_LOOPS */
.LbackLoop1done:
        bbci.l  a4, 3, .Lback2
        # copy 8 bytes
        addi    a3, a3, -8
        l32i    a6, a3,  0
        l32i    a7, a3,  4
        addi    a5, a5, -8
        s32i    a6, a5,  0
        s32i    a7, a5,  4
.Lback2:
        bbsi.l  a4, 2, .Lback3
        bbsi.l  a4, 1, .Lback4
        bbsi.l  a4, 0, .Lback5
        abi_ret_default
.Lback3:
        # copy 4 bytes
        addi    a3, a3, -4
        l32i    a6, a3,  0
        addi    a5, a5, -4
        s32i    a6, a5,  0
        bbsi.l  a4, 1, .Lback4
        bbsi.l  a4, 0, .Lback5
        abi_ret_default
.Lback4:
        # copy 2 bytes
        addi    a3, a3, -2
        l16ui   a6, a3,  0
        addi    a5, a5, -2
        s16i    a6, a5,  0
        bbsi.l  a4, 0, .Lback5
        abi_ret_default
.Lback5:
        # copy 1 byte
        addi    a3, a3, -1
        l8ui    a6, a3,  0
        addi    a5, a5, -1
        s8i     a6, a5,  0
        abi_ret_default

/*
 * Destination is aligned, Source is unaligned
 */

        .align  4
.Lbacksrcunaligned:
        _beqz   a4, .Lbackdone  # avoid loading anything for zero-length copies
        # copy 16 bytes per iteration for word-aligned dst and unaligned src
        __ssa8  a3              # set shift amount from byte offset
#define SIM_CHECKS_ALIGNMENT    1       /* set to 1 when running on ISS with
                                         * the lint or ferret client, or 0
                                         * to save a few cycles */
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
        and     a11, a3, a8     # save unalignment offset for below
        sub     a3, a3, a11     # align a3
#endif
        l32i    a6, a3, 0       # load first word
#if XCHAL_HAVE_LOOPS
        loopnez a7, .LbackLoop2done
#else /* !XCHAL_HAVE_LOOPS */
        beqz    a7, .LbackLoop2done
        slli    a10, a7, 4
        sub     a10, a3, a10    # a10 = start of first 16B source chunk
#endif /* !XCHAL_HAVE_LOOPS */
.LbackLoop2:
        addi    a3, a3, -16
        l32i    a7, a3, 12
        l32i    a8, a3,  8
        addi    a5, a5, -16
        __src_b a6, a7, a6
        s32i    a6, a5, 12
        l32i    a9, a3,  4
        __src_b a7, a8, a7
        s32i    a7, a5,  8
        l32i    a6, a3,  0
        __src_b a8, a9, a8
        s32i    a8, a5,  4
        __src_b a9, a6, a9
        s32i    a9, a5,  0
#if !XCHAL_HAVE_LOOPS
        bne     a3, a10, .LbackLoop2 # continue loop if a3:src != a10:src_start
#endif /* !XCHAL_HAVE_LOOPS */
.LbackLoop2done:
        bbci.l  a4, 3, .Lback12
        # copy 8 bytes
        addi    a3, a3, -8
        l32i    a7, a3,  4
        l32i    a8, a3,  0
        addi    a5, a5, -8
        __src_b a6, a7, a6
        s32i    a6, a5,  4
        __src_b a7, a8, a7
        s32i    a7, a5,  0
        mov     a6, a8
.Lback12:
        bbci.l  a4, 2, .Lback13
        # copy 4 bytes
        addi    a3, a3, -4
        l32i    a7, a3,  0
        addi    a5, a5, -4
        __src_b a6, a7, a6
        s32i    a6, a5,  0
        mov     a6, a7
.Lback13:
#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
        add     a3, a3, a11     # readjust a3 with correct misalignment
#endif
        bbsi.l  a4, 1, .Lback14
        bbsi.l  a4, 0, .Lback15
.Lbackdone:
        abi_ret_default
.Lback14:
        # copy 2 bytes
        addi    a3, a3, -2
        l8ui    a6, a3,  0
        l8ui    a7, a3,  1
        addi    a5, a5, -2
        s8i     a6, a5,  0
        s8i     a7, a5,  1
        bbsi.l  a4, 0, .Lback15
        abi_ret_default
.Lback15:
        # copy 1 byte
        addi    a3, a3, -1
        addi    a5, a5, -1
        l8ui    a6, a3,  0
        s8i     a6, a5,  0
        abi_ret_default

ENDPROC(__memmove)
EXPORT_SYMBOL(__memmove)
EXPORT_SYMBOL(memmove)