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 mempy for the case of just copying a page.
   Prefetch strategy empirically optimised against RTL simulations
   of SH5-101 cut2 eval chip with Cayman board DDR memory.

   Parameters:
   r2 : source effective address (start of page)
   r3 : destination effective address (start of page)

   Always copies 4096 bytes.

   Points to review.
   * Currently the prefetch is 4 lines ahead and the alloco is 2 lines ahead.
     It seems like the prefetch needs to be at at least 4 lines ahead to get
     the data into the cache in time, and the allocos contend with outstanding
     prefetches for the same cache set, so it's better to have the numbers
     different.
   */

        .section .text..SHmedia32,"ax"
        .little

        .balign 8
        .global sh64_page_copy
sh64_page_copy:

        /* Copy 4096 bytes worth of data from r2 to r3.
           Do prefetches 4 lines ahead.
           Do alloco 2 lines ahead */

        pta 1f, tr1
        pta 2f, tr2
        pta 3f, tr3
        ptabs r18, tr0

#if 0
        /* TAKum03020 */
        ld.q r2, 0x00, r63
        ld.q r2, 0x20, r63
        ld.q r2, 0x40, r63
        ld.q r2, 0x60, r63
#endif
        alloco r3, 0x00
        synco           ! TAKum03020
        alloco r3, 0x20
        synco           ! TAKum03020

        movi 3968, r6
        add  r3, r6, r6
        addi r6, 64, r7
        addi r7, 64, r8
        sub r2, r3, r60
        addi r60, 8, r61
        addi r61, 8, r62
        addi r62, 8, r23
        addi r60, 0x80, r22

/* Minimal code size.  The extra branches inside the loop don't cost much
   because they overlap with the time spent waiting for prefetches to
   complete. */
1:
#if 0
        /* TAKum03020 */
        bge/u r3, r6, tr2  ! skip prefetch for last 4 lines
        ldx.q r3, r22, r63 ! prefetch 4 lines hence
#endif
2:
        bge/u r3, r7, tr3  ! skip alloco for last 2 lines
        alloco r3, 0x40    ! alloc destination line 2 lines ahead
        synco           ! TAKum03020
3:
        ldx.q r3, r60, r36
        ldx.q r3, r61, r37
        ldx.q r3, r62, r38
        ldx.q r3, r23, r39
        st.q  r3,   0, r36
        st.q  r3,   8, r37
        st.q  r3,  16, r38
        st.q  r3,  24, r39
        addi r3, 32, r3
        bgt/l r8, r3, tr1

        blink tr0, r63     ! return