/*      $OpenBSD: bcopy.S,v 1.8 2015/08/31 02:53:56 guenther Exp $      */
/*      $NetBSD: bcopy.S,v 1.3 1996/10/17 03:08:11 cgd Exp $    */

/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: Trevor Blackwell.  Support for use as memcpy() and memmove()
 *         added by Chris Demetriou.
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

#include "SYS.h"

#define SRCREG          a0
#define DSTREG          a1
#define SIZEREG         a2

/*
 * Copy bytes.
 *
 * void bcopy(char *from, char *to, size_t len);
 *
 * No matter how invoked, the source and destination registers
 * for calculation.  There's no point in copying them to "working"
 * registers, since the code uses their values "in place," and
 * copying them would be slower.
 */

LEAF(bcopy,3)
        /* Check for zero length */
        beq     SIZEREG,bcopy_done

        /* Check for overlap */
        subq    DSTREG,SRCREG,t5
        cmpult  t5,SIZEREG,t5
        bne     t5,bcopy_overlap

        /* a3 = end address */
        addq    SRCREG,SIZEREG,a3

        /* Get the first word */
        ldq_u   t2,0(SRCREG)

        /* Do they have the same alignment? */
        xor     SRCREG,DSTREG,t0
        and     t0,7,t0
        and     DSTREG,7,t1
        bne     t0,bcopy_different_alignment

        /* src & dst have same alignment */
        beq     t1,bcopy_all_aligned

        ldq_u   t3,0(DSTREG)
        addq    SIZEREG,t1,SIZEREG
        mskqh   t2,SRCREG,t2
        mskql   t3,SRCREG,t3
        or      t2,t3,t2

        /* Dst is 8-byte aligned */

bcopy_all_aligned:
        /* If less than 8 bytes,skip loop */
        subq    SIZEREG,1,t0
        and     SIZEREG,7,SIZEREG
        bic     t0,7,t0
        beq     t0,bcopy_samealign_lp_end

bcopy_samealign_lp:
        stq_u   t2,0(DSTREG)
        addq    DSTREG,8,DSTREG
        ldq_u   t2,8(SRCREG)
        subq    t0,8,t0
        addq    SRCREG,8,SRCREG
        bne     t0,bcopy_samealign_lp

bcopy_samealign_lp_end:
        /* If we're done, exit */
        bne     SIZEREG,bcopy_small_left
        stq_u   t2,0(DSTREG)
        RET

bcopy_small_left:
        mskql   t2,SIZEREG,t4
        ldq_u   t3,0(DSTREG)
        mskqh   t3,SIZEREG,t3
        or      t4,t3,t4
        stq_u   t4,0(DSTREG)
        RET

bcopy_different_alignment:
        /*
         * this is the fun part
         */
        addq    SRCREG,SIZEREG,a3
        cmpule  SIZEREG,8,t0
        bne     t0,bcopy_da_finish

        beq     t1,bcopy_da_noentry

        /* Do the initial partial word */
        subq    zero,DSTREG,t0
        and     t0,7,t0
        ldq_u   t3,7(SRCREG)
        extql   t2,SRCREG,t2
        extqh   t3,SRCREG,t3
        or      t2,t3,t5
        insql   t5,DSTREG,t5
        ldq_u   t6,0(DSTREG)
        mskql   t6,DSTREG,t6
        or      t5,t6,t5
        stq_u   t5,0(DSTREG)
        addq    SRCREG,t0,SRCREG
        addq    DSTREG,t0,DSTREG
        subq    SIZEREG,t0,SIZEREG
        ldq_u   t2,0(SRCREG)

bcopy_da_noentry:
        subq    SIZEREG,1,t0
        bic     t0,7,t0
        and     SIZEREG,7,SIZEREG
        beq     t0,bcopy_da_finish2

bcopy_da_lp:
        ldq_u   t3,7(SRCREG)
        addq    SRCREG,8,SRCREG
        extql   t2,SRCREG,t4
        extqh   t3,SRCREG,t5
        subq    t0,8,t0
        or      t4,t5,t5
        stq     t5,0(DSTREG)
        addq    DSTREG,8,DSTREG
        beq     t0,bcopy_da_finish1
        ldq_u   t2,7(SRCREG)
        addq    SRCREG,8,SRCREG
        extql   t3,SRCREG,t4
        extqh   t2,SRCREG,t5
        subq    t0,8,t0
        or      t4,t5,t5
        stq     t5,0(DSTREG)
        addq    DSTREG,8,DSTREG
        bne     t0,bcopy_da_lp

bcopy_da_finish2:
        /* Do the last new word */
        mov     t2,t3

bcopy_da_finish1:
        /* Do the last partial word */
        ldq_u   t2,-1(a3)
        extql   t3,SRCREG,t3
        extqh   t2,SRCREG,t2
        or      t2,t3,t2
        br      zero,bcopy_samealign_lp_end

bcopy_da_finish:
        /* Do the last word in the next source word */
        ldq_u   t3,-1(a3)
        extql   t2,SRCREG,t2
        extqh   t3,SRCREG,t3
        or      t2,t3,t2
        insqh   t2,DSTREG,t3
        insql   t2,DSTREG,t2
        lda     t4,-1(zero)
        mskql   t4,SIZEREG,t5
        cmovne  t5,t5,t4
        insqh   t4,DSTREG,t5
        insql   t4,DSTREG,t4
        addq    DSTREG,SIZEREG,a4
        ldq_u   t6,0(DSTREG)
        ldq_u   t7,-1(a4)
        bic     t6,t4,t6
        bic     t7,t5,t7
        and     t2,t4,t2
        and     t3,t5,t3
        or      t2,t6,t2
        or      t3,t7,t3
        stq_u   t3,-1(a4)
        stq_u   t2,0(DSTREG)
        RET

bcopy_overlap:
        /*
         * Basically equivalent to previous case, only backwards.
         * Not quite as highly optimized
         */
        addq    SRCREG,SIZEREG,a3
        addq    DSTREG,SIZEREG,a4

        /* less than 8 bytes - don't worry about overlap */
        cmpule  SIZEREG,8,t0
        bne     t0,bcopy_ov_short

        /* Possibly do a partial first word */
        and     a4,7,t4
        beq     t4,bcopy_ov_nostart2
        subq    a3,t4,a3
        subq    a4,t4,a4
        ldq_u   t1,0(a3)
        subq    SIZEREG,t4,SIZEREG
        ldq_u   t2,7(a3)
        ldq     t3,0(a4)
        extql   t1,a3,t1
        extqh   t2,a3,t2
        or      t1,t2,t1
        mskqh   t3,t4,t3
        mskql   t1,t4,t1
        or      t1,t3,t1
        stq     t1,0(a4)

bcopy_ov_nostart2:
        bic     SIZEREG,7,t4
        and     SIZEREG,7,SIZEREG
        beq     t4,bcopy_ov_lp_end

bcopy_ov_lp:
        /* This could be more pipelined, but it doesn't seem worth it */
        ldq_u   t0,-8(a3)
        subq    a4,8,a4
        ldq_u   t1,-1(a3)
        subq    a3,8,a3
        extql   t0,a3,t0
        extqh   t1,a3,t1
        subq    t4,8,t4
        or      t0,t1,t0
        stq     t0,0(a4)
        bne     t4,bcopy_ov_lp

bcopy_ov_lp_end:
        beq     SIZEREG,bcopy_done

        ldq_u   t0,0(SRCREG)
        ldq_u   t1,7(SRCREG)
        ldq_u   t2,0(DSTREG)
        extql   t0,SRCREG,t0
        extqh   t1,SRCREG,t1
        or      t0,t1,t0
        insql   t0,DSTREG,t0
        mskql   t2,DSTREG,t2
        or      t2,t0,t2
        stq_u   t2,0(DSTREG)

bcopy_done:
        RET

bcopy_ov_short:
        ldq_u   t2,0(SRCREG)
        br      zero,bcopy_da_finish

        END_WEAK(bcopy)