483 lines
12 KiB
ArmAsm
483 lines
12 KiB
ArmAsm
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Unified implementation of memcpy, memmove and the __copy_user backend.
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*
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* Copyright (C) 1998, 99, 2000, 01, 2002 Ralf Baechle (ralf@gnu.org)
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* Copyright (C) 1999, 2000, 01, 2002 Silicon Graphics, Inc.
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* Copyright (C) 2002 Broadcom, Inc.
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* memcpy/copy_user author: Mark Vandevoorde
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*
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* Mnemonic names for arguments to memcpy/__copy_user
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*/
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#include <asm/asm.h>
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#include <asm/asm-offsets.h>
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#include <asm/export.h>
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#include <asm/regdef.h>
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#define dst a0
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#define src a1
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#define len a2
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/*
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* Spec
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*
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* memcpy copies len bytes from src to dst and sets v0 to dst.
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* It assumes that
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* - src and dst don't overlap
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* - src is readable
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* - dst is writable
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* memcpy uses the standard calling convention
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*
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* __copy_user copies up to len bytes from src to dst and sets a2 (len) to
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* the number of uncopied bytes due to an exception caused by a read or write.
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* __copy_user assumes that src and dst don't overlap, and that the call is
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* implementing one of the following:
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* copy_to_user
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* - src is readable (no exceptions when reading src)
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* copy_from_user
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* - dst is writable (no exceptions when writing dst)
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* __copy_user uses a non-standard calling convention; see
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* arch/mips/include/asm/uaccess.h
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*
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* When an exception happens on a load, the handler must
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# ensure that all of the destination buffer is overwritten to prevent
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* leaking information to user mode programs.
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*/
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/*
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* Implementation
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*/
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/*
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* The exception handler for loads requires that:
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* 1- AT contain the address of the byte just past the end of the source
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* of the copy,
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* 2- src_entry <= src < AT, and
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* 3- (dst - src) == (dst_entry - src_entry),
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* The _entry suffix denotes values when __copy_user was called.
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*
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* (1) is set up up by uaccess.h and maintained by not writing AT in copy_user
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* (2) is met by incrementing src by the number of bytes copied
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* (3) is met by not doing loads between a pair of increments of dst and src
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*
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* The exception handlers for stores adjust len (if necessary) and return.
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* These handlers do not need to overwrite any data.
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*
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* For __rmemcpy and memmove an exception is always a kernel bug, therefore
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* they're not protected.
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*/
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#define EXC(inst_reg,addr,handler) \
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9: inst_reg, addr; \
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.section __ex_table,"a"; \
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PTR 9b, handler; \
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.previous
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/*
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* Only on the 64-bit kernel we can made use of 64-bit registers.
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*/
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#define LOAD ld
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#define LOADL ldl
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#define LOADR ldr
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#define STOREL sdl
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#define STORER sdr
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#define STORE sd
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#define ADD daddu
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#define SUB dsubu
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#define SRL dsrl
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#define SRA dsra
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#define SLL dsll
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#define SLLV dsllv
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#define SRLV dsrlv
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#define NBYTES 8
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#define LOG_NBYTES 3
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/*
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* As we are sharing code base with the mips32 tree (which use the o32 ABI
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* register definitions). We need to redefine the register definitions from
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* the n64 ABI register naming to the o32 ABI register naming.
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*/
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#undef t0
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#undef t1
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#undef t2
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#undef t3
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#define t0 $8
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#define t1 $9
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#define t2 $10
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#define t3 $11
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#define t4 $12
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#define t5 $13
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#define t6 $14
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#define t7 $15
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#ifdef CONFIG_CPU_LITTLE_ENDIAN
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#define LDFIRST LOADR
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#define LDREST LOADL
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#define STFIRST STORER
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#define STREST STOREL
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#define SHIFT_DISCARD SLLV
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#else
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#define LDFIRST LOADL
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#define LDREST LOADR
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#define STFIRST STOREL
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#define STREST STORER
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#define SHIFT_DISCARD SRLV
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#endif
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#define FIRST(unit) ((unit)*NBYTES)
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#define REST(unit) (FIRST(unit)+NBYTES-1)
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#define UNIT(unit) FIRST(unit)
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#define ADDRMASK (NBYTES-1)
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.text
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.set noreorder
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.set noat
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/*
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* A combined memcpy/__copy_user
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* __copy_user sets len to 0 for success; else to an upper bound of
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* the number of uncopied bytes.
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* memcpy sets v0 to dst.
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*/
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.align 5
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LEAF(memcpy) /* a0=dst a1=src a2=len */
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EXPORT_SYMBOL(memcpy)
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move v0, dst /* return value */
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__memcpy:
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FEXPORT(__copy_user)
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EXPORT_SYMBOL(__copy_user)
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/*
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* Note: dst & src may be unaligned, len may be 0
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* Temps
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*/
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#
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# Octeon doesn't care if the destination is unaligned. The hardware
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# can fix it faster than we can special case the assembly.
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#
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pref 0, 0(src)
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sltu t0, len, NBYTES # Check if < 1 word
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bnez t0, copy_bytes_checklen
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and t0, src, ADDRMASK # Check if src unaligned
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bnez t0, src_unaligned
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sltu t0, len, 4*NBYTES # Check if < 4 words
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bnez t0, less_than_4units
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sltu t0, len, 8*NBYTES # Check if < 8 words
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bnez t0, less_than_8units
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sltu t0, len, 16*NBYTES # Check if < 16 words
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bnez t0, cleanup_both_aligned
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sltu t0, len, 128+1 # Check if len < 129
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bnez t0, 1f # Skip prefetch if len is too short
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sltu t0, len, 256+1 # Check if len < 257
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bnez t0, 1f # Skip prefetch if len is too short
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pref 0, 128(src) # We must not prefetch invalid addresses
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#
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# This is where we loop if there is more than 128 bytes left
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2: pref 0, 256(src) # We must not prefetch invalid addresses
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#
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# This is where we loop if we can't prefetch anymore
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1:
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EXC( LOAD t0, UNIT(0)(src), l_exc)
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EXC( LOAD t1, UNIT(1)(src), l_exc_copy)
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EXC( LOAD t2, UNIT(2)(src), l_exc_copy)
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EXC( LOAD t3, UNIT(3)(src), l_exc_copy)
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SUB len, len, 16*NBYTES
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EXC( STORE t0, UNIT(0)(dst), s_exc_p16u)
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EXC( STORE t1, UNIT(1)(dst), s_exc_p15u)
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EXC( STORE t2, UNIT(2)(dst), s_exc_p14u)
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EXC( STORE t3, UNIT(3)(dst), s_exc_p13u)
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EXC( LOAD t0, UNIT(4)(src), l_exc_copy)
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EXC( LOAD t1, UNIT(5)(src), l_exc_copy)
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EXC( LOAD t2, UNIT(6)(src), l_exc_copy)
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EXC( LOAD t3, UNIT(7)(src), l_exc_copy)
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EXC( STORE t0, UNIT(4)(dst), s_exc_p12u)
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EXC( STORE t1, UNIT(5)(dst), s_exc_p11u)
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EXC( STORE t2, UNIT(6)(dst), s_exc_p10u)
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ADD src, src, 16*NBYTES
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EXC( STORE t3, UNIT(7)(dst), s_exc_p9u)
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ADD dst, dst, 16*NBYTES
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EXC( LOAD t0, UNIT(-8)(src), l_exc_copy_rewind16)
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EXC( LOAD t1, UNIT(-7)(src), l_exc_copy_rewind16)
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EXC( LOAD t2, UNIT(-6)(src), l_exc_copy_rewind16)
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EXC( LOAD t3, UNIT(-5)(src), l_exc_copy_rewind16)
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EXC( STORE t0, UNIT(-8)(dst), s_exc_p8u)
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EXC( STORE t1, UNIT(-7)(dst), s_exc_p7u)
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EXC( STORE t2, UNIT(-6)(dst), s_exc_p6u)
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EXC( STORE t3, UNIT(-5)(dst), s_exc_p5u)
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EXC( LOAD t0, UNIT(-4)(src), l_exc_copy_rewind16)
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EXC( LOAD t1, UNIT(-3)(src), l_exc_copy_rewind16)
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EXC( LOAD t2, UNIT(-2)(src), l_exc_copy_rewind16)
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EXC( LOAD t3, UNIT(-1)(src), l_exc_copy_rewind16)
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EXC( STORE t0, UNIT(-4)(dst), s_exc_p4u)
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EXC( STORE t1, UNIT(-3)(dst), s_exc_p3u)
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EXC( STORE t2, UNIT(-2)(dst), s_exc_p2u)
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EXC( STORE t3, UNIT(-1)(dst), s_exc_p1u)
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sltu t0, len, 256+1 # See if we can prefetch more
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beqz t0, 2b
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sltu t0, len, 128 # See if we can loop more time
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beqz t0, 1b
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nop
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#
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# Jump here if there are less than 16*NBYTES left.
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#
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cleanup_both_aligned:
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beqz len, done
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sltu t0, len, 8*NBYTES
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bnez t0, less_than_8units
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nop
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EXC( LOAD t0, UNIT(0)(src), l_exc)
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EXC( LOAD t1, UNIT(1)(src), l_exc_copy)
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EXC( LOAD t2, UNIT(2)(src), l_exc_copy)
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EXC( LOAD t3, UNIT(3)(src), l_exc_copy)
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SUB len, len, 8*NBYTES
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EXC( STORE t0, UNIT(0)(dst), s_exc_p8u)
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EXC( STORE t1, UNIT(1)(dst), s_exc_p7u)
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EXC( STORE t2, UNIT(2)(dst), s_exc_p6u)
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EXC( STORE t3, UNIT(3)(dst), s_exc_p5u)
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EXC( LOAD t0, UNIT(4)(src), l_exc_copy)
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EXC( LOAD t1, UNIT(5)(src), l_exc_copy)
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EXC( LOAD t2, UNIT(6)(src), l_exc_copy)
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EXC( LOAD t3, UNIT(7)(src), l_exc_copy)
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EXC( STORE t0, UNIT(4)(dst), s_exc_p4u)
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EXC( STORE t1, UNIT(5)(dst), s_exc_p3u)
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EXC( STORE t2, UNIT(6)(dst), s_exc_p2u)
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EXC( STORE t3, UNIT(7)(dst), s_exc_p1u)
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ADD src, src, 8*NBYTES
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beqz len, done
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ADD dst, dst, 8*NBYTES
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#
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# Jump here if there are less than 8*NBYTES left.
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#
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less_than_8units:
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sltu t0, len, 4*NBYTES
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bnez t0, less_than_4units
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nop
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EXC( LOAD t0, UNIT(0)(src), l_exc)
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EXC( LOAD t1, UNIT(1)(src), l_exc_copy)
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EXC( LOAD t2, UNIT(2)(src), l_exc_copy)
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EXC( LOAD t3, UNIT(3)(src), l_exc_copy)
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SUB len, len, 4*NBYTES
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EXC( STORE t0, UNIT(0)(dst), s_exc_p4u)
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EXC( STORE t1, UNIT(1)(dst), s_exc_p3u)
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EXC( STORE t2, UNIT(2)(dst), s_exc_p2u)
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EXC( STORE t3, UNIT(3)(dst), s_exc_p1u)
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ADD src, src, 4*NBYTES
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beqz len, done
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ADD dst, dst, 4*NBYTES
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#
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# Jump here if there are less than 4*NBYTES left. This means
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# we may need to copy up to 3 NBYTES words.
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#
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less_than_4units:
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sltu t0, len, 1*NBYTES
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bnez t0, copy_bytes_checklen
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nop
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#
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# 1) Copy NBYTES, then check length again
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#
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EXC( LOAD t0, 0(src), l_exc)
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SUB len, len, NBYTES
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sltu t1, len, 8
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EXC( STORE t0, 0(dst), s_exc_p1u)
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ADD src, src, NBYTES
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bnez t1, copy_bytes_checklen
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ADD dst, dst, NBYTES
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#
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# 2) Copy NBYTES, then check length again
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#
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EXC( LOAD t0, 0(src), l_exc)
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SUB len, len, NBYTES
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sltu t1, len, 8
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EXC( STORE t0, 0(dst), s_exc_p1u)
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ADD src, src, NBYTES
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bnez t1, copy_bytes_checklen
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ADD dst, dst, NBYTES
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#
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# 3) Copy NBYTES, then check length again
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#
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EXC( LOAD t0, 0(src), l_exc)
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SUB len, len, NBYTES
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ADD src, src, NBYTES
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ADD dst, dst, NBYTES
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b copy_bytes_checklen
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EXC( STORE t0, -8(dst), s_exc_p1u)
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src_unaligned:
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#define rem t8
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SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter
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beqz t0, cleanup_src_unaligned
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and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES
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1:
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/*
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* Avoid consecutive LD*'s to the same register since some mips
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* implementations can't issue them in the same cycle.
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* It's OK to load FIRST(N+1) before REST(N) because the two addresses
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* are to the same unit (unless src is aligned, but it's not).
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*/
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EXC( LDFIRST t0, FIRST(0)(src), l_exc)
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EXC( LDFIRST t1, FIRST(1)(src), l_exc_copy)
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SUB len, len, 4*NBYTES
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EXC( LDREST t0, REST(0)(src), l_exc_copy)
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EXC( LDREST t1, REST(1)(src), l_exc_copy)
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EXC( LDFIRST t2, FIRST(2)(src), l_exc_copy)
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EXC( LDFIRST t3, FIRST(3)(src), l_exc_copy)
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EXC( LDREST t2, REST(2)(src), l_exc_copy)
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EXC( LDREST t3, REST(3)(src), l_exc_copy)
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ADD src, src, 4*NBYTES
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EXC( STORE t0, UNIT(0)(dst), s_exc_p4u)
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EXC( STORE t1, UNIT(1)(dst), s_exc_p3u)
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EXC( STORE t2, UNIT(2)(dst), s_exc_p2u)
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EXC( STORE t3, UNIT(3)(dst), s_exc_p1u)
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bne len, rem, 1b
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ADD dst, dst, 4*NBYTES
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cleanup_src_unaligned:
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beqz len, done
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and rem, len, NBYTES-1 # rem = len % NBYTES
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beq rem, len, copy_bytes
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nop
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1:
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EXC( LDFIRST t0, FIRST(0)(src), l_exc)
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EXC( LDREST t0, REST(0)(src), l_exc_copy)
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SUB len, len, NBYTES
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EXC( STORE t0, 0(dst), s_exc_p1u)
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ADD src, src, NBYTES
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bne len, rem, 1b
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ADD dst, dst, NBYTES
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copy_bytes_checklen:
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beqz len, done
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nop
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copy_bytes:
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/* 0 < len < NBYTES */
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#define COPY_BYTE(N) \
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EXC( lb t0, N(src), l_exc); \
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SUB len, len, 1; \
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beqz len, done; \
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EXC( sb t0, N(dst), s_exc_p1)
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COPY_BYTE(0)
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COPY_BYTE(1)
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COPY_BYTE(2)
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COPY_BYTE(3)
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COPY_BYTE(4)
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COPY_BYTE(5)
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EXC( lb t0, NBYTES-2(src), l_exc)
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SUB len, len, 1
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jr ra
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EXC( sb t0, NBYTES-2(dst), s_exc_p1)
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done:
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jr ra
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nop
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END(memcpy)
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l_exc_copy_rewind16:
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/* Rewind src and dst by 16*NBYTES for l_exc_copy */
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SUB src, src, 16*NBYTES
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SUB dst, dst, 16*NBYTES
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l_exc_copy:
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/*
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* Copy bytes from src until faulting load address (or until a
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* lb faults)
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*
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* When reached by a faulting LDFIRST/LDREST, THREAD_BUADDR($28)
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* may be more than a byte beyond the last address.
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* Hence, the lb below may get an exception.
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*
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* Assumes src < THREAD_BUADDR($28)
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*/
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LOAD t0, TI_TASK($28)
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LOAD t0, THREAD_BUADDR(t0)
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1:
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EXC( lb t1, 0(src), l_exc)
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ADD src, src, 1
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sb t1, 0(dst) # can't fault -- we're copy_from_user
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bne src, t0, 1b
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ADD dst, dst, 1
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l_exc:
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LOAD t0, TI_TASK($28)
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LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address
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SUB len, AT, t0 # len number of uncopied bytes
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jr ra
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nop
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#define SEXC(n) \
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s_exc_p ## n ## u: \
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jr ra; \
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ADD len, len, n*NBYTES
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SEXC(16)
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SEXC(15)
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SEXC(14)
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SEXC(13)
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SEXC(12)
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SEXC(11)
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SEXC(10)
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SEXC(9)
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SEXC(8)
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SEXC(7)
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SEXC(6)
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SEXC(5)
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SEXC(4)
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SEXC(3)
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SEXC(2)
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SEXC(1)
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s_exc_p1:
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jr ra
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ADD len, len, 1
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s_exc:
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jr ra
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nop
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.align 5
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LEAF(memmove)
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EXPORT_SYMBOL(memmove)
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ADD t0, a0, a2
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ADD t1, a1, a2
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sltu t0, a1, t0 # dst + len <= src -> memcpy
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sltu t1, a0, t1 # dst >= src + len -> memcpy
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and t0, t1
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beqz t0, __memcpy
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move v0, a0 /* return value */
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beqz a2, r_out
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END(memmove)
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/* fall through to __rmemcpy */
|
|
LEAF(__rmemcpy) /* a0=dst a1=src a2=len */
|
|
sltu t0, a1, a0
|
|
beqz t0, r_end_bytes_up # src >= dst
|
|
nop
|
|
ADD a0, a2 # dst = dst + len
|
|
ADD a1, a2 # src = src + len
|
|
|
|
r_end_bytes:
|
|
lb t0, -1(a1)
|
|
SUB a2, a2, 0x1
|
|
sb t0, -1(a0)
|
|
SUB a1, a1, 0x1
|
|
bnez a2, r_end_bytes
|
|
SUB a0, a0, 0x1
|
|
|
|
r_out:
|
|
jr ra
|
|
move a2, zero
|
|
|
|
r_end_bytes_up:
|
|
lb t0, (a1)
|
|
SUB a2, a2, 0x1
|
|
sb t0, (a0)
|
|
ADD a1, a1, 0x1
|
|
bnez a2, r_end_bytes_up
|
|
ADD a0, a0, 0x1
|
|
|
|
jr ra
|
|
move a2, zero
|
|
END(__rmemcpy)
|