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-rw-r--r--arch/sh64/lib/page_clear.S54
1 files changed, 54 insertions, 0 deletions
diff --git a/arch/sh64/lib/page_clear.S b/arch/sh64/lib/page_clear.S
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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 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
+
+