58e97e521c
Add the `LIBC_PREVENT_STRING_KERNEL` and `LIBC_PREVENT_STRING_USER` that are meant to be selected by the chip if no libc implementation is going to be built. If selected, neither NuttX's software version of the libc nor any architecture-specific implementation will be built in the kernel or in the userspace, respectively. In this case, the linker may provide a ROM-defined version of the libc functions instead.
80 lines
2.2 KiB
ArmAsm
80 lines
2.2 KiB
ArmAsm
/****************************************************************************
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* libs/libc/machine/arm/armv8-m/gnu/arch_memmove.S
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*
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* Copyright (c) 2015 ARM Ltd
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the company may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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#include "libc.h"
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#ifdef LIBC_BUILD_STRING
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#include "arm_asm.h"
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.thumb
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.syntax unified
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.global memmove
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.type memmove, %function
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memmove:
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.fnstart
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.cfi_startproc
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prologue 4
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cmp r0, r1
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bls 3f
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adds r3, r1, r2
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cmp r0, r3
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bcs 3f
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adds r1, r0, r2
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cbz r2, 2f
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subs r2, r3, r2
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1:
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ldrb r4, [r3, #-1]!
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cmp r2, r3
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strb r4, [r1, #-1]!
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bne 1b
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2:
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.cfi_remember_state
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epilogue 4
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3:
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.cfi_restore_state
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cmp r2, #0
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beq 2b
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add r2, r2, r1
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subs r3, r0, #1
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4:
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ldrb r4, [r1], #1
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cmp r2, r1
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strb r4, [r3, #1]!
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bne 4b
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epilogue 4
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.cfi_endproc
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.cantunwind
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.fnend
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.size memmove, . - memmove
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#endif
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