Subversion Repositories openrisc

/*******************************************************************************

 *

 * Copyright (c) 1993 Intel Corporation

 *

 * Intel hereby grants you permission to copy, modify, and distribute this

 * software and its documentation.  Intel grants this permission provided

 * that the above copyright notice appears in all copies and that both the

 * copyright notice and this permission notice appear in supporting

 * documentation.  In addition, Intel grants this permission provided that

 * you prominently mark as "not part of the original" any modifications

 * made to this software or documentation, and that the name of Intel

 * Corporation not be used in advertising or publicity pertaining to

 * distribution of the software or the documentation without specific,

 * written prior permission.

 *

 * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR

 * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY

 * OR FITNESS FOR A PARTICULAR PURPOSE.  Intel makes no guarantee or

 * representations regarding the use of, or the results of the use of,

 * the software and documentation in terms of correctness, accuracy,

 * reliability, currentness, or otherwise; and you rely on the software,

 * documentation and results solely at your own risk.

 *

 * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,

 * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES

 * OF ANY KIND.  IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM

 * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.

 *

 ******************************************************************************/

        .file "memcp_ca.s"

#ifdef  __PIC

        .pic

#endif

#ifdef  __PID

        .pid

#endif

/*

 * (c) copyright 1988,1992,1993 Intel Corp., all rights reserved

 */

/*

        procedure memmove  (optimized assembler version for the CA)

        procedure memcpy   (optimized assembler version for the CA)

        dest_addr = memmove (dest_addr, src_addr, len)

        dest_addr = memcpy  (dest_addr, src_addr, len)

        copy len bytes pointed to by src_addr to the space pointed to by

        dest_addr.  Return the original dest_addr.

        Memcpy will fail if the source and destination string overlap

        (in particular, if the end of the source is overlapped by the

        beginning of the destination).  The behavior is undefined.

        This is acceptable according to the draft C standard.

        Memmove will not fail if overlap exists.

        Undefined behavior will also occur if the end of the source string

        (i.e. the terminating null byte) is in the last word of the program's

        allocated memory space.  This is so because, in several cases, the

        routine will fetch ahead one word.  Disallowing the fetch ahead would

        impose a severe performance penalty.

        This program handles five cases:

        1) both arguments start on a word boundary

        2) neither are word aligned, but they are offset by the same amount

        3) source is word aligned, destination is not

        4) destination is word aligned, source is not

        5) neither is word aligned, and they are offset by differing amounts

        At the time of this writing, only g0 thru g7 and g13 are available

        for use in this leafproc;  other registers would have to be saved and

        restored.  These nine registers, plus tricky use of g14 are sufficient

        to implement the routine.  The registers are used as follows:

        g0  dest ptr;  not modified, so that it may be returned

        g1  src ptr;  shift count

        g2  len

        g3  src ptr (word aligned)

        g4  dest ptr (word aligned)

        g5  -4 for Lbackwards move

        Little endian

                g6  lsw of double word for extraction of 4 bytes

                g7  msw of double word for extraction of 4 bytes

        Big endian

                g6  msw of double word for extraction of 4 bytes

                g7  lsw of double word for extraction of 4 bytes

        g13 return address

        g14 byte extracted.

*/

#if __i960_BIG_ENDIAN__

#define MSW g6

#define LSW g7

#else

#define LSW g6

#define MSW g7

#endif

        .globl  _memmove, _memcpy

        .globl  __memmove, __memcpy

        .leafproc       _memmove, __memmove

        .leafproc       _memcpy,  __memcpy

        .align  2

_memcpy:

_memmove:

#ifndef __PIC

        lda     Lrett,g14

#else

        lda     Lrett-(.+8)(ip),g14

#endif

__memcpy:

__memmove:

        cmpibge.f 0,g2,Lquick_exit # Lexit if number of bytes to move is <= zero.

        cmpo    g0,g1           # if dest starts earlier than src ...

         lda    (g14),g13       # preserve return address

        addo    g2,g1,g5        # compute addr of byte after last byte of src

         be.f   Lexit_code      # no move necessary if src and dest are same

        concmpo g5,g0           # ... or if dest starts after end of src ...

        notand  g1,3,g3         # extract word addr of start of src

         bg.f   Lbackwards      # ... then drop thru, else do move backwards

        cmpo    g3,g1           # check alignment of src

         ld     (g3),LSW        # fetch word containing at least first byte

        notand  g0,3,g4         # extract word addr of start of dest

         lda    4(g3),g3        # advance src word addr

         bne.f  Lcase_245       # branch if src is NOT word aligned

Lcase_13:

        cmpo    g0,g4           # check alignment of dest

        subo    4,g4,g4         # store is pre-incrementing;  back up dest addr

         be.t   Lcase_1         # branch if dest word aligned

Lcase_3:                                # src is word aligned; dest is not

        addo    8,g4,g4         # move dest word ptr to first word boundary

         lda    (g0),g1         # copy dest byte ptr

        mov     LSW,MSW         # make copy of first word of src

         lda    32,g14          # initialize shift count to zero (mod 32)

Lcase_25:

Lcase_3_cloop_at_start:         # character copying loop for start of dest str

        cmpdeci 0,g2,g2         # is max_bytes exhausted?

        be.f    Lexit_code      # Lexit if max_bytes is exhausted

#if __i960_BIG_ENDIAN__

        rotate  8,MSW,MSW       # move next byte into position for extraction

        subo    8,g14,g14       # augment the shift counter

         stob   MSW,(g1)        # store the byte in dest

#else

        addo    8,g14,g14       # augment the shift counter

         stob   MSW,(g1)        # store the byte in dest

        shro    8,MSW,MSW       # move next byte into position for extraction

#endif

         lda    1(g1),g1        # post-increment dest ptr

        cmpobne.t g1,g4,Lcase_3_cloop_at_start # branch if reached word boundary

        ld      (g3),MSW        # fetch msw of operand for double shift

Lcase_4:

Lcase_3_wloop:

        cmpi    g2,4            # less than four bytes to move?

         lda    4(g3),g3        # post-increment src word addr

        eshro   g14,g6,g1       # extract 4 bytes of src

         bl.f   Lcase_3_cloop   # branch if < four bytes left to move

        mov     MSW,LSW         # move msw to lsw

         ld     (g3),MSW        # pre-fetch msw of operand for double shift

        subi    4,g2,g2         # decrease max_byte count by the 4 bytes moved

         st     g1,(g4)         # store 4 bytes to dest

        addo    4,g4,g4         # post-increment dest ptr

         b      Lcase_3_wloop

Lcase_1_wloop:                  # word copying loop

        subi    4,g2,g2         # decrease max_byte count by the 4 bytes moved

         ld     (g3),LSW        # pre-fetch next word of src

        addo    4,g3,g3         # post-increment src addr

         st     g1,(g4)         # store word in dest string

Lcase_1:                                # src and dest are word aligned

        cmpi    g2,4            # check for fewer than four bytes to move

        addo    4,g4,g4         # pre-increment dest addr

         lda    (LSW),g1        # keep a copy of the src word

         bge.t  Lcase_1_wloop   # branch if at least four bytes to copy

Lcase_3_cloop:

        cmpibe.f 0,g2,Lexit_code        # Lexit if max_bytes is exhausted

Lcase_1_cloop:

#if __i960_BIG_ENDIAN__

        rotate  8,g1,g1         # move next byte into position for extraction

#endif

        subi    1,g2,g2

         stob   g1,(g4)         # store the byte in dest

        cmpi    0,g2

         lda    1(g4),g4        # post-increment dest byte addr

#if ! __i960_BIG_ENDIAN__

        shro    8,g1,g1         # move next byte into position for extraction

#endif

         bne.t  Lcase_1_cloop   # Lexit if max_bytes is exhausted

Lexit_code:

        mov     0,g14           # conform to register conventions

        bx      (g13)           # g0 = addr of dest;  g14 = 0

Lrett:

        ret

Lcase_245:

        cmpo    g0,g4           # check alignment of dest

         ld     (g3),MSW        # pre-fetch second half

        and     3,g1,g1         # compute shift count

        shlo    3,g1,g14

#if __i960_BIG_ENDIAN__

        subo    g14,0,g14       # adjust shift count for big endian

#endif

         be.t   Lcase_4         # branch if dest is word aligned

        or      g4,g1,g1        # is src earlier in word, later, or sync w/ dst

        cmpo    g0,g1           # < indicates first word of dest has more bytes

         lda    4(g4),g4        # move dest word addr to first word boundary

        eshro   g14,g6,g5       # extract four bytes

         lda    (g0),g1

#if __i960_BIG_ENDIAN__

         bge.f  1f

#else

         bg.f   1f

#endif

        mov     MSW,LSW

         lda    4(g3),g3        # move src word addr to second word boundary

1:

        mov     g5,MSW

         b      Lcase_25

Lbackwards:

        notand  g5,3,MSW        # extract word addr of byte after end of src

        cmpo    MSW,g5          # check alignment of end of src

        subo    4,MSW,g3        # retreat src word addr

        addo    g2,g0,g1        # compute addr of byte after end of dest

        notand  g1,3,g4         # extract word addr of start of dest

         bne.f  Lcase.245       # branch if src is NOT word aligned

Lcase.13:

        cmpo    g1,g4           # check alignment of dest

         ld     (g3),MSW        # fetch last word of src

        subo    4,g3,g3         # retreat src word addr

         be.t   Lcase.1         # branch if dest word aligned

Lcase.3:                        # src is word aligned; dest is not

        mov     MSW,LSW         # make copy of first word of src

         lda    32,g14          # initialize shift count to zero (mod 32)

Lcase.25:

Lcase.3_cloop_at_start:         # character copying loop for start of dest str

        cmpdeci 0,g2,g2         # is max.bytes exhausted?

         be.f   Lexit_code      # Lexit if max_bytes is exhausted

#if ! __i960_BIG_ENDIAN__

        rotate  8,LSW,LSW       # move next byte into position for storing

#endif

         lda    -1(g1),g1       # pre-decrement dest ptr

        cmpo    g1,g4           # have we reached word boundary in dest yet?

         stob   LSW,(g1)        # store the byte in dest

#if __i960_BIG_ENDIAN__

        shro    8,LSW,LSW       # move next byte into position for storing

        addo    8,g14,g14       # augment the shift counter

#else

        subo    8,g14,g14       # augment the shift counter

#endif

         bne.t  Lcase.3_cloop_at_start  # branch if reached word boundary?

        ld      (g3),LSW        # fetch lsw of operand for double shift

#if __i960_BIG_ENDIAN__

        cmpobne 0,g14,Lcase.3_wloop

Lcase.3_wloop2:

        cmpi    g2,4            # less than four bytes to move?

         lda    -4(g3),g3       # post-decrement src word addr

        mov     MSW,g1          # extract 4 bytes of src

         lda    (LSW),MSW       # move lsw to msw

        subo    4,g4,g4         # pre-decrement dest ptr

         bl.f   Lcase.3_cloop   # branch if < four bytes left to move

         ld     (g3),LSW        # pre-fetch lsw of operand for double shift

        subi    4,g2,g2         # decrease max.byte count by the 4 bytes moved

         st     g1,(g4)         # store 4 bytes to dest

         b      Lcase.3_wloop2

#endif

Lcase.4:

Lcase.3_wloop:

        cmpi    g2,4            # less than four bytes to move?

         lda    -4(g3),g3       # post-decrement src word addr

        eshro   g14,g6,g1       # extract 4 bytes of src

         lda    (LSW),MSW       # move lsw to msw

        subo    4,g4,g4         # pre-decrement dest ptr

         bl.f   Lcase.3_cloop   # branch if < four bytes left to move

        ld      (g3),LSW        # pre-fetch lsw of operand for double shift

        subi    4,g2,g2         # decrease max.byte count by the 4 bytes moved

         st     g1,(g4)         # store 4 bytes to dest

         b      Lcase.3_wloop

Lcase.1_wloop:                  # word copying loop

        subi    4,g2,g2         # decrease max.byte count by the 4 bytes moved

         ld     (g3),MSW        # pre-fetch next word of src

        subo    4,g3,g3         # post-decrement src addr

         st     g1,(g4)         # store word in dest string

Lcase.1:                                # src and dest are word aligned

        cmpi    g2,4            # check for fewer than four bytes to move

        subo    4,g4,g4         # pre-decrement dest addr

         lda    (MSW),g1        # keep a copy of the src word

         bge.t  Lcase.1_wloop   # branch if at least four bytes to copy

Lcase.3_cloop:

        cmpibe.f 0,g2,Lexit_code        # Lexit if max_bytes is exhausted

#if ! __i960_BIG_ENDIAN__

        rotate  8,g1,g1         # move next byte into position for storing

#endif

         lda    4(g4),g4        # pre-decremented dest addr 4 too much

Lcase.1_cloop:

        subi    1,g4,g4         # pre-decrement dest byte addr

        cmpi    g4,g0           # has dest ptr reached beginning of dest?

         stob   g1,(g4)         # store the byte in dest

#if __i960_BIG_ENDIAN__

        shro    8,g1,g1         # move next byte into position for storing

#else

        rotate  8,g1,g1         # move next byte into position for storing

#endif

         bne.t  Lcase.1_cloop   # Lexit if move is completed

        b       Lexit_code

Lcase.245:

        cmpo    g1,g4           # check alignment of dest

         ld     (MSW),MSW       # pre-fetch word with at least last byte

        and     3,g5,g5         # compute shift count

         ld     (g3),LSW        # pre-fetch second to last word

        shlo    3,g5,g14

#if __i960_BIG_ENDIAN__

        subo    g14,0,g14       # adjust shift count for big endian

#endif

         be.t   Lcase.4         # branch if dest is word aligned

        or      g4,g5,g5        # is src earlier in word, later, or sync w/ dst

        cmpo    g1,g5           # < indicates last word of dest has less bytes

        eshro   g14,g6,g5       # extract four bytes

         bl.t   1f

        mov     LSW,MSW

#if ! __i960_BIG_ENDIAN__

         be.t   1f

#endif

        subo    4,g3,g3         # move src word addr to second word boundary

1:

        mov     g5,LSW

         b      Lcase.25

Lquick_exit:

        mov     g14,g13

         b      Lexit_code

/* end of memmove */