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!
! Fast SH memcpy
!
! by Toshiyasu Morita (tm@netcom.com)
! hacked by J"orn Rernnecke (joern.rennecke@superh.com) ("o for o-umlaut)
! SH5 code Copyright 2002 SuperH Ltd.
!
! Entry: ARG0: destination pointer
!        ARG1: source pointer
!        ARG3: byte count
!
! Exit:  RESULT: destination pointer
!        any other registers in the range r0-r7: trashed
!
! Notes: Usually one wants to do small reads and write a longword, but
!        unfortunately it is difficult in some cases to concatanate bytes
!        into a longword on the SH, so this does a longword read and small
!        writes.
!
! This implementation makes two assumptions about how it is called:
!
! 1.: If the byte count is nonzero, the address of the last byte to be
!     copied is unsigned greater than the address of the first byte to
!     be copied.  This could be easily swapped for a signed comparison,
!     but the algorithm used needs some comparison.
!
! 2.: When there are two or three bytes in the last word of an 11-or-more
!     bytes memory chunk to b copied, the rest of the word can be read
!     without side effects.
!     This could be easily changed by increasing the minumum size of
!     a fast memcpy and the amount subtracted from r7 before L_2l_loop be 2,
!     however, this would cost a few extra cyles on average.
!     For SHmedia, the assumption is that any quadword can be read in its
!     enirety if at least one byte is included in the copy.
!

#include "asm.h"

ENTRY(memcpy)

#if __SHMEDIA__

#define LDUAQ(P,O,D0,D1) ldlo.q P,O,D0; ldhi.q P,O+7,D1
#define STUAQ(P,O,D0,D1) stlo.q P,O,D0; sthi.q P,O+7,D1
#define LDUAL(P,O,D0,D1) ldlo.l P,O,D0; ldhi.l P,O+3,D1
#define STUAL(P,O,D0,D1) stlo.l P,O,D0; sthi.l P,O+3,D1

        ld.b r3,0,r63
        pta/l Large,tr0
        movi 25,r0
        bgeu/u r4,r0,tr0
        nsb r4,r0
        shlli r0,5,r0
        movi (L1-L0+63*32 + 1) & 0xffff,r1
        sub r1, r0, r0
L0:     ptrel r0,tr0
        add r2,r4,r5
        ptabs r18,tr1
        add r3,r4,r6
        blink tr0,r63

        .balign 8
L1:
        /* 0 byte memcpy */
        blink tr1,r63

L4_7:   /* 4..7 byte memcpy cntd. */
        stlo.l r2, 0, r0
        or r6, r7, r6
        sthi.l r5, -1, r6
        stlo.l r5, -4, r6
        blink tr1,r63

L2_3:   /* 2 or 3 byte memcpy cntd. */
        st.b r5,-1,r6
        blink tr1,r63

        /* 1 byte memcpy */
        ld.b r3,0,r0
        st.b r2,0,r0
        blink tr1,r63

L8_15:  /* 8..15 byte memcpy cntd. */
        stlo.q r2, 0, r0
        or r6, r7, r6
        sthi.q r5, -1, r6
        stlo.q r5, -8, r6
        blink tr1,r63
        
        /* 2 or 3 byte memcpy */
        ld.b r3,0,r0
        ld.b r2,0,r63
        ld.b r3,1,r1
        st.b r2,0,r0
        pta/l L2_3,tr0
        ld.b r6,-1,r6
        st.b r2,1,r1
        blink tr0, r63

        /* 4 .. 7 byte memcpy */
        LDUAL (r3, 0, r0, r1)
        pta L4_7, tr0
        ldlo.l r6, -4, r7
        or r0, r1, r0
        sthi.l r2, 3, r0
        ldhi.l r6, -1, r6
        blink tr0, r63

        /* 8 .. 15 byte memcpy */
        LDUAQ (r3, 0, r0, r1)
        pta L8_15, tr0
        ldlo.q r6, -8, r7
        or r0, r1, r0
        sthi.q r2, 7, r0
        ldhi.q r6, -1, r6
        blink tr0, r63

        /* 16 .. 24 byte memcpy */
        LDUAQ (r3, 0, r0, r1)
        LDUAQ (r3, 8, r8, r9)
        or r0, r1, r0
        sthi.q r2, 7, r0
        or r8, r9, r8
        sthi.q r2, 15, r8
        ldlo.q r6, -8, r7
        ldhi.q r6, -1, r6
        stlo.q r2, 8, r8
        stlo.q r2, 0, r0
        or r6, r7, r6
        sthi.q r5, -1, r6
        stlo.q r5, -8, r6
        blink tr1,r63

Large:
        ld.b r2, 0, r63
        pta/l  Loop_ua, tr1
        ori r3, -8, r7
        sub r2, r7, r22
        sub r3, r2, r6
        add r2, r4, r5
        ldlo.q r3, 0, r0
        addi r5, -16, r5
        movi 64+8, r27 // could subtract r7 from that.
        stlo.q r2, 0, r0
        sthi.q r2, 7, r0
        ldx.q r22, r6, r0
        bgtu/l r27, r4, tr1

        addi r5, -48, r27
        pta/l Loop_line, tr0
        addi r6, 64, r36
        addi r6, -24, r19
        addi r6, -16, r20
        addi r6, -8, r21

Loop_line:
        ldx.q r22, r36, r63
        alloco r22, 32
        addi r22, 32, r22
        ldx.q r22, r19, r23
        sthi.q r22, -25, r0
        ldx.q r22, r20, r24
        ldx.q r22, r21, r25
        stlo.q r22, -32, r0
        ldx.q r22, r6,  r0
        sthi.q r22, -17, r23
        sthi.q r22,  -9, r24
        sthi.q r22,  -1, r25
        stlo.q r22, -24, r23
        stlo.q r22, -16, r24
        stlo.q r22,  -8, r25
        bgeu r27, r22, tr0

Loop_ua:
        addi r22, 8, r22
        sthi.q r22, -1, r0
        stlo.q r22, -8, r0
        ldx.q r22, r6, r0
        bgtu/l r5, r22, tr1

        add r3, r4, r7
        ldlo.q r7, -8, r1
        sthi.q r22, 7, r0
        ldhi.q r7, -1, r7
        ptabs r18,tr1
        stlo.q r22, 0, r0
        or r1, r7, r1
        sthi.q r5, 15, r1
        stlo.q r5, 8, r1
        blink tr1, r63

#else /* ! SHMEDIA, i.e. SH1 .. SH4 / SHcompact */

#ifdef __SH5__
#define DST r2
#define SRC r3
#define COUNT r4
#define TMP0 r5
#define TMP1 r6
#define RESULT r2
#else
#define DST r4
#define SRC r5
#define COUNT r6
#define TMP0 r2
#define TMP1 r3
#define RESULT r0
#endif

#ifdef __LITTLE_ENDIAN__
        ! Little endian version copies with increasing addresses.
        mov DST,TMP1    ! Save return value
        mov #11,r0      ! Check if small number of bytes
        cmp/hs r0,COUNT
                        ! COUNT becomes src end address
        SL(bf, L_small, add SRC,COUNT)
        mov #1,r1
        tst r1,SRC      ! check if source even
        SL(bt, L_even, mov COUNT,r7)
        mov.b @SRC+,r0  ! no, make it even.
        mov.b r0,@DST
        add #1,DST
L_even: tst r1,DST      ! check if destination is even
        add #-3,r7
        SL(bf, L_odddst, mov #2,r1)
        tst r1,DST      ! check if destination is 4-byte aligned
        mov DST,r0
        SL(bt, L_al4dst, sub SRC,r0)
        mov.w @SRC+,TMP0
        mov.w TMP0,@DST
        ! add #2,DST  DST is dead here.
L_al4dst:
        tst r1,SRC
        bt L_al4both
        mov.w @SRC+,r1
        swap.w r1,r1
        add #-6,r0
        add #-6,r7      ! r7 := src end address minus 9.
        .align 2
L_2l_loop:
        mov.l @SRC+,TMP0 ! Read & write two longwords per iteration
        xtrct TMP0,r1
        mov.l r1,@(r0,SRC)
        cmp/hs r7,SRC
        mov.l @SRC+,r1
        xtrct r1,TMP0
        mov.l TMP0,@(r0,SRC)
        bf L_2l_loop
        add #-2,SRC
        bra  L_cleanup
        add #5,r0
L_al4both:
        add #-4,r0
        .align 2
L_al4both_loop:
        mov.l @SRC+,DST   ! Read longword, write longword per iteration
        cmp/hs r7,SRC
        SL(bf, L_al4both_loop, mov.l DST,@(r0,SRC))

        bra L_cleanup
        add #3,r0

L_odddst:
        tst r1,SRC
        SL(bt, L_al4src, add #-1,DST)
        mov.w @SRC+,r0
        mov.b r0,@(1,DST)
        shlr8 r0
        mov.b r0,@(2,DST)
        add #2,DST
L_al4src:
        .align 2
L_odd_loop:
        mov.l @SRC+,r0   ! Read longword, write byte, word, byte per iteration
        cmp/hs r7,SRC
        mov.b r0,@(1,DST)
        shlr8 r0
        mov.w r0,@(2,DST)
        shlr16 r0
        mov.b r0,@(4,DST)
        SL(bf, L_odd_loop, add #4,DST)
        .align 2 ! avoid nop in more frequently executed code.
L_cleanup2:
        mov     DST,r0
        sub     SRC,r0
L_cleanup:
        cmp/eq  COUNT,SRC
        bt      L_ready
        .align 2
L_cleanup_loop:
        mov.b   @SRC+,r1
        cmp/eq  COUNT,SRC
        mov.b   r1,@(r0,SRC)
        bf      L_cleanup_loop
L_ready:
        rts
        mov     TMP1,RESULT
L_small:
        bra L_cleanup2
        add #-1,DST
#else /* ! __LITTLE_ENDIAN__ */
        ! Big endian version copies with decreasing addresses.
        mov DST,r0
        add COUNT,r0
        sub DST,SRC
        mov #11,r1
        cmp/hs r1,COUNT
        SL(bf, L_small, add #-1,SRC)
        mov SRC,TMP1
        add r0,TMP1
        shlr TMP1
        SL(bt, L_even,
        mov DST,r7)
        mov.b @(r0,SRC),TMP0
        add #-1,TMP1
        mov.b TMP0,@-r0
L_even:
        tst #1,r0
        add #-1,SRC
        SL(bf, L_odddst, add #8,r7)
        tst #2,r0
        bt L_al4dst
        add #-1,TMP1
        mov.w @(r0,SRC),r1
        mov.w r1,@-r0
L_al4dst:
        shlr TMP1
        bt L_al4both
        mov.w @(r0,SRC),r1
        swap.w r1,r1
        add #4,r7
        add #-4,SRC
        .align 2
L_2l_loop:
        mov.l @(r0,SRC),TMP0
        xtrct TMP0,r1
        mov.l r1,@-r0
        cmp/hs r7,r0
        mov.l @(r0,SRC),r1
        xtrct r1,TMP0
        mov.l TMP0,@-r0
        bt L_2l_loop
        bra L_cleanup
        add #5,SRC

        nop ! avoid nop in executed code.
L_al4both:
        add #-2,SRC
        .align 2
L_al4both_loop:
        mov.l @(r0,SRC),r1
        cmp/hs r7,r0
        SL(bt, L_al4both_loop,
        mov.l r1,@-r0)
        bra L_cleanup
        add #3,SRC

        nop ! avoid nop in executed code.
L_odddst:
        shlr TMP1
        bt L_al4src
        mov.w @(r0,SRC),r1
        mov.b r1,@-r0
        shlr8 r1
        mov.b r1,@-r0
L_al4src:
        add #-2,SRC
        .align 2
L_odd_loop:
        mov.l @(r0,SRC),TMP0
        cmp/hs r7,r0
        mov.b TMP0,@-r0
        shlr8 TMP0
        mov.w TMP0,@-r0
        shlr16 TMP0
        mov.b TMP0,@-r0
        bt L_odd_loop

        add #3,SRC
L_cleanup:
L_small:
        cmp/eq DST,r0
        bt L_ready
        add #1,DST
        .align 2
L_cleanup_loop:
        mov.b @(r0,SRC),TMP0
        cmp/eq DST,r0
        mov.b TMP0,@-r0
        bf L_cleanup_loop
L_ready:
        rts
        mov r0,RESULT
#endif /* ! __LITTLE_ENDIAN__ */
#endif /* ! SHMEDIA */