135 lines
3.3 KiB
ArmAsm
135 lines
3.3 KiB
ArmAsm
/* memcpy.S: optimised assembly memcpy
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*
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* Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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.text
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.p2align 4
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###############################################################################
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#
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# void *memcpy(void *to, const char *from, size_t count)
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#
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# - NOTE: must not use any stack. exception detection performs function return
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# to caller's fixup routine, aborting the remainder of the copy
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#
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###############################################################################
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.globl memcpy,__memcpy_end
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.type memcpy,@function
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memcpy:
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or.p gr8,gr9,gr4
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orcc gr10,gr0,gr0,icc3
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or.p gr10,gr4,gr4
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beqlr icc3,#0
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# optimise based on best common alignment for to, from & count
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andicc.p gr4,#0x0f,gr0,icc0
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setlos #8,gr11
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andicc.p gr4,#0x07,gr0,icc1
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beq icc0,#0,memcpy_16
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andicc.p gr4,#0x03,gr0,icc0
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beq icc1,#0,memcpy_8
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andicc.p gr4,#0x01,gr0,icc1
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beq icc0,#0,memcpy_4
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setlos.p #1,gr11
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beq icc1,#0,memcpy_2
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# do byte by byte copy
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sub.p gr8,gr11,gr3
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sub gr9,gr11,gr9
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0: ldubu.p @(gr9,gr11),gr4
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subicc gr10,#1,gr10,icc0
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stbu.p gr4,@(gr3,gr11)
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bne icc0,#2,0b
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bralr
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# do halfword by halfword copy
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memcpy_2:
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setlos #2,gr11
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sub.p gr8,gr11,gr3
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sub gr9,gr11,gr9
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0: lduhu.p @(gr9,gr11),gr4
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subicc gr10,#2,gr10,icc0
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sthu.p gr4,@(gr3,gr11)
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bne icc0,#2,0b
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bralr
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# do word by word copy
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memcpy_4:
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setlos #4,gr11
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sub.p gr8,gr11,gr3
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sub gr9,gr11,gr9
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0: ldu.p @(gr9,gr11),gr4
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subicc gr10,#4,gr10,icc0
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stu.p gr4,@(gr3,gr11)
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bne icc0,#2,0b
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bralr
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# do double-word by double-word copy
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memcpy_8:
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sub.p gr8,gr11,gr3
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sub gr9,gr11,gr9
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0: lddu.p @(gr9,gr11),gr4
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subicc gr10,#8,gr10,icc0
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stdu.p gr4,@(gr3,gr11)
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bne icc0,#2,0b
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bralr
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# do quad-word by quad-word copy
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memcpy_16:
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sub.p gr8,gr11,gr3
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sub gr9,gr11,gr9
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0: lddu @(gr9,gr11),gr4
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lddu.p @(gr9,gr11),gr6
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subicc gr10,#16,gr10,icc0
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stdu gr4,@(gr3,gr11)
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stdu.p gr6,@(gr3,gr11)
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bne icc0,#2,0b
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bralr
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__memcpy_end:
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.size memcpy, __memcpy_end-memcpy
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###############################################################################
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#
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# copy to/from userspace
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# - return the number of bytes that could not be copied (0 on complete success)
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#
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# long __memcpy_user(void *dst, const void *src, size_t count)
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#
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###############################################################################
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.globl __memcpy_user, __memcpy_user_error_lr, __memcpy_user_error_handler
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.type __memcpy_user,@function
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__memcpy_user:
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movsg lr,gr7
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subi.p sp,#8,sp
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add gr8,gr10,gr6 ; calculate expected end address
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stdi gr6,@(sp,#0)
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# abuse memcpy to do the dirty work
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call memcpy
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__memcpy_user_error_lr:
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ldi.p @(sp,#4),gr7
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setlos #0,gr8
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jmpl.p @(gr7,gr0)
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addi sp,#8,sp
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# deal any exception generated by memcpy
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# GR8 - memcpy's current dest address
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# GR11 - memset's step value (index register for store insns)
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__memcpy_user_error_handler:
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lddi.p @(sp,#0),gr4 ; load GR4 with dst+count, GR5 with ret addr
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add gr11,gr3,gr7
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sub.p gr4,gr7,gr8
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addi sp,#8,sp
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jmpl @(gr5,gr0)
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.size __memcpy_user, .-__memcpy_user
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