219 lines
5.2 KiB
ArmAsm
219 lines
5.2 KiB
ArmAsm
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! SPDX-License-Identifier: GPL-2.0
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!
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! Fast SH memcpy
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!
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! by Toshiyasu Morita (tm@netcom.com)
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! hacked by J"orn Rernnecke (joern.rennecke@superh.com) ("o for o-umlaut)
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! SH5 code Copyright 2002 SuperH Ltd.
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!
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! Entry: ARG0: destination pointer
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! ARG1: source pointer
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! ARG2: byte count
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!
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! Exit: RESULT: destination pointer
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! any other registers in the range r0-r7: trashed
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!
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! Notes: Usually one wants to do small reads and write a longword, but
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! unfortunately it is difficult in some cases to concatanate bytes
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! into a longword on the SH, so this does a longword read and small
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! writes.
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!
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! This implementation makes two assumptions about how it is called:
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!
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! 1.: If the byte count is nonzero, the address of the last byte to be
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! copied is unsigned greater than the address of the first byte to
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! be copied. This could be easily swapped for a signed comparison,
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! but the algorithm used needs some comparison.
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!
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! 2.: When there are two or three bytes in the last word of an 11-or-more
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! bytes memory chunk to b copied, the rest of the word can be read
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! without side effects.
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! This could be easily changed by increasing the minimum size of
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! a fast memcpy and the amount subtracted from r7 before L_2l_loop be 2,
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! however, this would cost a few extra cyles on average.
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! For SHmedia, the assumption is that any quadword can be read in its
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! enirety if at least one byte is included in the copy.
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/* Imported into Linux kernel by Richard Curnow. This is used to implement the
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__copy_user function in the general case, so it has to be a distinct
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function from intra-kernel memcpy to allow for exception fix-ups in the
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event that the user pointer is bad somewhere in the copy (e.g. due to
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running off the end of the vma).
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Note, this algorithm will be slightly wasteful in the case where the source
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and destination pointers are equally aligned, because the stlo/sthi pairs
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could then be merged back into single stores. If there are a lot of cache
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misses, this is probably offset by the stall lengths on the preloads.
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*/
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/* NOTE : Prefetches removed and allocos guarded by synco to avoid TAKum03020
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* erratum. The first two prefetches are nop-ed out to avoid upsetting the
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* instruction counts used in the jump address calculation.
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* */
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.section .text..SHmedia32,"ax"
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.little
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.balign 32
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.global copy_user_memcpy
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.global copy_user_memcpy_end
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copy_user_memcpy:
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#define LDUAQ(P,O,D0,D1) ldlo.q P,O,D0; ldhi.q P,O+7,D1
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#define STUAQ(P,O,D0,D1) stlo.q P,O,D0; sthi.q P,O+7,D1
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#define LDUAL(P,O,D0,D1) ldlo.l P,O,D0; ldhi.l P,O+3,D1
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#define STUAL(P,O,D0,D1) stlo.l P,O,D0; sthi.l P,O+3,D1
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nop ! ld.b r3,0,r63 ! TAKum03020
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pta/l Large,tr0
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movi 25,r0
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bgeu/u r4,r0,tr0
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nsb r4,r0
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shlli r0,5,r0
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movi (L1-L0+63*32 + 1) & 0xffff,r1
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sub r1, r0, r0
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L0: ptrel r0,tr0
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add r2,r4,r5
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ptabs r18,tr1
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add r3,r4,r6
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blink tr0,r63
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/* Rearranged to make cut2 safe */
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.balign 8
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L4_7: /* 4..7 byte memcpy cntd. */
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stlo.l r2, 0, r0
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or r6, r7, r6
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sthi.l r5, -1, r6
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stlo.l r5, -4, r6
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blink tr1,r63
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.balign 8
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L1: /* 0 byte memcpy */
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nop
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blink tr1,r63
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nop
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nop
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nop
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nop
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L2_3: /* 2 or 3 byte memcpy cntd. */
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st.b r5,-1,r6
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blink tr1,r63
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/* 1 byte memcpy */
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ld.b r3,0,r0
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st.b r2,0,r0
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blink tr1,r63
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L8_15: /* 8..15 byte memcpy cntd. */
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stlo.q r2, 0, r0
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or r6, r7, r6
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sthi.q r5, -1, r6
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stlo.q r5, -8, r6
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blink tr1,r63
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/* 2 or 3 byte memcpy */
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ld.b r3,0,r0
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nop ! ld.b r2,0,r63 ! TAKum03020
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ld.b r3,1,r1
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st.b r2,0,r0
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pta/l L2_3,tr0
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ld.b r6,-1,r6
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st.b r2,1,r1
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blink tr0, r63
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/* 4 .. 7 byte memcpy */
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LDUAL (r3, 0, r0, r1)
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pta L4_7, tr0
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ldlo.l r6, -4, r7
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or r0, r1, r0
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sthi.l r2, 3, r0
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ldhi.l r6, -1, r6
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blink tr0, r63
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/* 8 .. 15 byte memcpy */
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LDUAQ (r3, 0, r0, r1)
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pta L8_15, tr0
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ldlo.q r6, -8, r7
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or r0, r1, r0
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sthi.q r2, 7, r0
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ldhi.q r6, -1, r6
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blink tr0, r63
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/* 16 .. 24 byte memcpy */
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LDUAQ (r3, 0, r0, r1)
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LDUAQ (r3, 8, r8, r9)
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or r0, r1, r0
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sthi.q r2, 7, r0
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or r8, r9, r8
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sthi.q r2, 15, r8
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ldlo.q r6, -8, r7
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ldhi.q r6, -1, r6
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stlo.q r2, 8, r8
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stlo.q r2, 0, r0
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or r6, r7, r6
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sthi.q r5, -1, r6
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stlo.q r5, -8, r6
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blink tr1,r63
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Large:
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! ld.b r2, 0, r63 ! TAKum03020
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pta/l Loop_ua, tr1
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ori r3, -8, r7
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sub r2, r7, r22
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sub r3, r2, r6
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add r2, r4, r5
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ldlo.q r3, 0, r0
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addi r5, -16, r5
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movi 64+8, r27 ! could subtract r7 from that.
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stlo.q r2, 0, r0
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sthi.q r2, 7, r0
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ldx.q r22, r6, r0
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bgtu/l r27, r4, tr1
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addi r5, -48, r27
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pta/l Loop_line, tr0
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addi r6, 64, r36
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addi r6, -24, r19
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addi r6, -16, r20
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addi r6, -8, r21
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Loop_line:
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! ldx.q r22, r36, r63 ! TAKum03020
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alloco r22, 32
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synco
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addi r22, 32, r22
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ldx.q r22, r19, r23
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sthi.q r22, -25, r0
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ldx.q r22, r20, r24
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ldx.q r22, r21, r25
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stlo.q r22, -32, r0
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ldx.q r22, r6, r0
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sthi.q r22, -17, r23
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sthi.q r22, -9, r24
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sthi.q r22, -1, r25
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stlo.q r22, -24, r23
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stlo.q r22, -16, r24
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stlo.q r22, -8, r25
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bgeu r27, r22, tr0
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Loop_ua:
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addi r22, 8, r22
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sthi.q r22, -1, r0
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stlo.q r22, -8, r0
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ldx.q r22, r6, r0
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bgtu/l r5, r22, tr1
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add r3, r4, r7
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ldlo.q r7, -8, r1
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sthi.q r22, 7, r0
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ldhi.q r7, -1, r7
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ptabs r18,tr1
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stlo.q r22, 0, r0
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or r1, r7, r1
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sthi.q r5, 15, r1
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stlo.q r5, 8, r1
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blink tr1, r63
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copy_user_memcpy_end:
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nop
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