Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

   Copyright 2003 Richard Curnow, SuperH (UK) Ltd.

   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.

   Tight version of memset for the case of just clearing a page.  It turns out

   that having the alloco's spaced out slightly due to the increment/branch

   pair causes them to contend less for access to the cache.  Similarly,

   keeping the stores apart from the allocos causes less contention.  => Do two

   separate loops.  Do multiple stores per loop to amortise the

   increment/branch cost a little.

   Parameters:

   r2 : source effective address (start of page)

   Always clears 4096 bytes.

   Note : alloco guarded by synco to avoid TAKum03020 erratum

*/

        .section .text..SHmedia32,"ax"

        .little

        .balign 8

        .global sh64_page_clear

sh64_page_clear:

        pta/l 1f, tr1

        pta/l 2f, tr2

        ptabs/l r18, tr0

        movi 4096, r7

        add  r2, r7, r7

        add  r2, r63, r6

1:

        alloco r6, 0

        synco   ! TAKum03020

        addi    r6, 32, r6

        bgt/l   r7, r6, tr1

        add  r2, r63, r6

2:

        st.q  r6,   0, r63

        st.q  r6,   8, r63

        st.q  r6,  16, r63

        st.q  r6,  24, r63

        addi r6, 32, r6

        bgt/l r7, r6, tr2

        blink tr0, r63