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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 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 |