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/*
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 clear_page
clear_page:
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
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