141 lines
3.0 KiB
ArmAsm
141 lines
3.0 KiB
ArmAsm
/*
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* Copyright (c) 2014 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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/* Implementation of strcmp for ARMv6m. This version is only used in
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ARMv6-M when we want an efficient implementation. Otherwize if the
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code size is preferred, strcmp-armv4t.S will be used. */
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.thumb_func
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.syntax unified
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.arch armv6-m
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.macro DoSub n, label
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subs r0, r0, r1
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#ifdef __ARM_BIG_ENDIAN
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lsrs r1, r4, \n
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#else
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lsls r1, r4, \n
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#endif
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orrs r1, r0
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bne \label
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.endm
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.macro Byte_Test n, label
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lsrs r0, r2, \n
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lsrs r1, r3, \n
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DoSub \n, \label
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.endm
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.text
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def_fn strcmp
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.cfi_startproc
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mov r2, r0
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push {r4, r5, r6, lr}
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orrs r2, r1
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lsls r2, r2, #30
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bne 6f
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ldr r5, =0x01010101
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lsls r6, r5, #7
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1:
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ldmia r0!, {r2}
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ldmia r1!, {r3}
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subs r4, r2, r5
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bics r4, r2
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ands r4, r6
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beq 3f
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#ifdef __ARM_BIG_ENDIAN
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Byte_Test #24, 4f
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Byte_Test #16, 4f
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Byte_Test #8, 4f
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b 7f
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3:
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cmp r2, r3
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beq 1b
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cmp r2, r3
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#else
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uxtb r0, r2
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uxtb r1, r3
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DoSub #24, 2f
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uxth r0, r2
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uxth r1, r3
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DoSub #16, 2f
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lsls r0, r2, #8
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lsls r1, r3, #8
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lsrs r0, r0, #8
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lsrs r1, r1, #8
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DoSub #8, 2f
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lsrs r0, r2, #24
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lsrs r1, r3, #24
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subs r0, r0, r1
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2:
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pop {r4, r5, r6, pc}
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3:
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cmp r2, r3
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beq 1b
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rev r0, r2
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rev r1, r3
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cmp r0, r1
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#endif
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bls 5f
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movs r0, #1
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4:
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pop {r4, r5, r6, pc}
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5:
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movs r0, #0
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mvns r0, r0
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pop {r4, r5, r6, pc}
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6:
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ldrb r2, [r0, #0]
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ldrb r3, [r1, #0]
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adds r0, #1
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adds r1, #1
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cmp r2, #0
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beq 7f
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cmp r2, r3
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bne 7f
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ldrb r2, [r0, #0]
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ldrb r3, [r1, #0]
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adds r0, #1
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adds r1, #1
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cmp r2, #0
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beq 7f
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cmp r2, r3
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beq 6b
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7:
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subs r0, r2, r3
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pop {r4, r5, r6, pc}
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.cfi_endproc
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.size strcmp, . - strcmp
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