/*-
 * Copyright (c) 2018 Instituto de Pesquisas Eldorado
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the author nor the names of its contributors may
 *    be used to endorse or promote products derived from this software
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */


#include <machine/asm.h>
#if 0
        RCSID("$NetBSD: strcpy.S,v 1.0 2018/05/08 13:00:49 lbianc Exp $")
#endif

ENTRY(__strcpy_arch_2_05)
        mr      %r8, %r3

/* 
 * Aligning the reading address, even if it is already aligned to avoid
 * performance degradation with strings with 8 bytes or less.
 */
.Lalignment:
        lbz     %r0,0(%r4)
        cmpdi   cr7,%r0,0
        stb     %r0,0(%r8)
        beq     cr7,.Lexit
        addi    %r4,%r4,1
        addi    %r8,%r8,1
        andi.   %r0,%r4,0x7
        bne     .Lalignment

/* Copy by double word with aligned address. */
.Lcopy_dw:
        ld      %r0,0(%r4)
        xor     %r6,%r6,%r6
        cmpb    %r5,%r0,%r6
        cmpdi   cr7,%r5,0
        bne     cr7,.Lcheck_zero
        /* Backward r8 to use stdu instruction in Lcopy_dw_loop */
        addi    %r8,%r8,-8
.Lcopy_dw_loop:
        stdu    %r0,8(%r8)
        ldu     %r0,8(%r4)
        cmpb    %r5,%r0,%r6
        cmpdi   cr7,%r5,0
        beq     cr7,.Lcopy_dw_loop

        addi    %r8,%r8,8   /* Forward r8 to use std instruction. */
#if defined(__BIG_ENDIAN__)
/* Find where the zero is located. */
.Lcheck_zero:
        rldicr. %r5,%r0,0,7
        beq     .Lfound_on_byte_0
        rldicr. %r7,%r0,8,7
        beq     .Lfound_on_byte_1
        rldicr. %r7,%r0,16,7
        beq     .Lfound_on_byte_2
        rldicr. %r7,%r0,24,7
        beq     .Lfound_on_byte_3
        andis.  %r7,%r0,0xff00
        beq     .Lfound_on_byte_4
        andis.  %r7,%r0,0xff
        beq     .Lfound_on_byte_5
        andi.   %r7,%r0,0xff00
        beq     .Lfound_on_byte_6

/* Copy the last string bytes according to the string end position. */
.Lfound_on_byte_7:
        std     %r0,0(%r8)
        b       .Lexit

.Lfound_on_byte_6:
        srdi    %r6,%r0,32
        stw     %r6,0(%r8)
        srdi    %r6,%r0,16
        sth     %r6,4(%r8)
        srdi    %r6,%r0,8
        stb     %r6,6(%r8)
        b       .Lexit

.Lfound_on_byte_5:
        srdi    %r6,%r0,32
        stw     %r6,0(%r8)
        srdi    %r6,%r0,16
        sth     %r6,4(%r8)
        b       .Lexit

.Lfound_on_byte_4:
        srdi    %r6,%r0,32
        stw     %r6,0(%r8)
        srdi    %r6,%r0,24
        stb     %r6,4(%r8)
        b       .Lexit

.Lfound_on_byte_3:
        srdi    %r6,%r0,32
        stw     %r6,0(%r8)
        b       .Lexit

.Lfound_on_byte_2:
        srdi    %r6,%r0,48
        sth     %r6,0(%r8)
        srdi    %r6,%r0,40
        stb     %r6,2(%r8)
        b       .Lexit

.Lfound_on_byte_1:
        srdi    %r6,%r0,48
        sth     %r6,0(%r8)
        b       .Lexit

.Lfound_on_byte_0:
        srdi    %r6,%r0,56
        stb     %r6,0(%r8)
#elif defined(__LITTLE_ENDIAN__)
/* Find where the zero is located. */
.Lcheck_zero:
        andi.   %r7,%r0,0xff
        beq     .Lfound_on_byte_0
        andi.   %r7,%r0,0xff00
        beq     .Lfound_on_byte_1
        andis.  %r7,%r0,0xff
        beq     .Lfound_on_byte_2
        andis.  %r7,%r0,0xff00
        beq     .Lfound_on_byte_3
        rldicr. %r7,%r0,24,7
        beq     .Lfound_on_byte_4
        rldicr. %r7,%r0,16,7
        beq     .Lfound_on_byte_5
        rldicr. %r7,%r0,8,7
        beq     .Lfound_on_byte_6

/* Copy the last string bytes according to the string end position. */
.Lfound_on_byte_7:
        std     %r0,0(%r8)
        b       .Lexit

.Lfound_on_byte_6:
        stw     %r0,0(%r8)
        srdi    %r6,%r0,32
        sth     %r6,4(%r8)
        srdi    %r6,%r0,48
        stb     %r6,6(%r8)
        b       .Lexit

.Lfound_on_byte_5:
        stw     %r0,0(%r8)
        srdi    %r6,%r0,32
        sth     %r6,4(%r8)
        b       .Lexit

.Lfound_on_byte_4:
        stw     %r0,0(%r8)
        srdi    %r6,%r0,32
        stb     %r6,4(%r8)
        b       .Lexit

.Lfound_on_byte_3:
        stw     %r0,0(%r8)
        b       .Lexit

.Lfound_on_byte_2:
        sth     %r0,0(%r8)
        srdi    %r6,%r0,16
        stb     %r6,2(%r8)
        b       .Lexit

.Lfound_on_byte_1:
        sth     %r0,0(%r8)
        b       .Lexit

.Lfound_on_byte_0:
        stb     %r0,0(%r8)
#else
#error "Unable to determine Endianness"
#endif
.Lexit:
        blr

END(__strcpy_arch_2_05)

        .section .note.GNU-stack,"",%progbits