207 строки
4.2 KiB
ArmAsm
207 строки
4.2 KiB
ArmAsm
/*
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* linux/arch/arm/lib/memmove.S
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*
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* Author: Nicolas Pitre
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* Created: Sep 28, 2005
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* Copyright: (C) MontaVista Software Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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/*
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* This can be used to enable code to cacheline align the source pointer.
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* Experiments on tested architectures (StrongARM and XScale) didn't show
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* this a worthwhile thing to do. That might be different in the future.
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*/
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//#define CALGN(code...) code
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#define CALGN(code...)
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.text
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/*
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* Prototype: void *memmove(void *dest, const void *src, size_t n);
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*
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* Note:
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*
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* If the memory regions don't overlap, we simply branch to memcpy which is
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* normally a bit faster. Otherwise the copy is done going downwards. This
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* is a transposition of the code from copy_template.S but with the copy
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* occurring in the opposite direction.
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*/
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ENTRY(memmove)
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subs ip, r0, r1
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cmphi r2, ip
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bls memcpy
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stmfd sp!, {r0, r4, lr}
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add r1, r1, r2
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add r0, r0, r2
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subs r2, r2, #4
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blt 8f
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ands ip, r0, #3
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PLD( pld [r1, #-4] )
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bne 9f
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ands ip, r1, #3
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bne 10f
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1: subs r2, r2, #(28)
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stmfd sp!, {r5 - r8}
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blt 5f
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CALGN( ands ip, r1, #31 )
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CALGN( sbcnes r4, ip, r2 ) @ C is always set here
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CALGN( bcs 2f )
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CALGN( adr r4, 6f )
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CALGN( subs r2, r2, ip ) @ C is set here
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CALGN( add pc, r4, ip )
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PLD( pld [r1, #-4] )
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2: PLD( subs r2, r2, #96 )
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PLD( pld [r1, #-32] )
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PLD( blt 4f )
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PLD( pld [r1, #-64] )
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PLD( pld [r1, #-96] )
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3: PLD( pld [r1, #-128] )
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4: ldmdb r1!, {r3, r4, r5, r6, r7, r8, ip, lr}
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subs r2, r2, #32
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stmdb r0!, {r3, r4, r5, r6, r7, r8, ip, lr}
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bge 3b
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PLD( cmn r2, #96 )
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PLD( bge 4b )
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5: ands ip, r2, #28
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rsb ip, ip, #32
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addne pc, pc, ip @ C is always clear here
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b 7f
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6: nop
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ldr r3, [r1, #-4]!
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ldr r4, [r1, #-4]!
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ldr r5, [r1, #-4]!
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ldr r6, [r1, #-4]!
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ldr r7, [r1, #-4]!
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ldr r8, [r1, #-4]!
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ldr lr, [r1, #-4]!
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add pc, pc, ip
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nop
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nop
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str r3, [r0, #-4]!
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str r4, [r0, #-4]!
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str r5, [r0, #-4]!
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str r6, [r0, #-4]!
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str r7, [r0, #-4]!
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str r8, [r0, #-4]!
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str lr, [r0, #-4]!
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CALGN( bcs 2b )
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7: ldmfd sp!, {r5 - r8}
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8: movs r2, r2, lsl #31
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ldrneb r3, [r1, #-1]!
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ldrcsb r4, [r1, #-1]!
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ldrcsb ip, [r1, #-1]
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strneb r3, [r0, #-1]!
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strcsb r4, [r0, #-1]!
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strcsb ip, [r0, #-1]
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ldmfd sp!, {r0, r4, pc}
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9: cmp ip, #2
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ldrgtb r3, [r1, #-1]!
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ldrgeb r4, [r1, #-1]!
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ldrb lr, [r1, #-1]!
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strgtb r3, [r0, #-1]!
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strgeb r4, [r0, #-1]!
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subs r2, r2, ip
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strb lr, [r0, #-1]!
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blt 8b
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ands ip, r1, #3
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beq 1b
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10: bic r1, r1, #3
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cmp ip, #2
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ldr r3, [r1, #0]
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beq 17f
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blt 18f
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.macro backward_copy_shift push pull
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subs r2, r2, #28
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blt 14f
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CALGN( ands ip, r1, #31 )
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CALGN( rsb ip, ip, #32 )
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CALGN( sbcnes r4, ip, r2 ) @ C is always set here
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CALGN( subcc r2, r2, ip )
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CALGN( bcc 15f )
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11: stmfd sp!, {r5 - r9}
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PLD( pld [r1, #-4] )
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PLD( subs r2, r2, #96 )
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PLD( pld [r1, #-32] )
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PLD( blt 13f )
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PLD( pld [r1, #-64] )
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PLD( pld [r1, #-96] )
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12: PLD( pld [r1, #-128] )
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13: ldmdb r1!, {r7, r8, r9, ip}
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mov lr, r3, push #\push
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subs r2, r2, #32
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ldmdb r1!, {r3, r4, r5, r6}
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orr lr, lr, ip, pull #\pull
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mov ip, ip, push #\push
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orr ip, ip, r9, pull #\pull
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mov r9, r9, push #\push
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orr r9, r9, r8, pull #\pull
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mov r8, r8, push #\push
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orr r8, r8, r7, pull #\pull
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mov r7, r7, push #\push
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orr r7, r7, r6, pull #\pull
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mov r6, r6, push #\push
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orr r6, r6, r5, pull #\pull
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mov r5, r5, push #\push
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orr r5, r5, r4, pull #\pull
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mov r4, r4, push #\push
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orr r4, r4, r3, pull #\pull
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stmdb r0!, {r4 - r9, ip, lr}
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bge 12b
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PLD( cmn r2, #96 )
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PLD( bge 13b )
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ldmfd sp!, {r5 - r9}
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14: ands ip, r2, #28
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beq 16f
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15: mov lr, r3, push #\push
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ldr r3, [r1, #-4]!
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subs ip, ip, #4
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orr lr, lr, r3, pull #\pull
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str lr, [r0, #-4]!
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bgt 15b
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CALGN( cmp r2, #0 )
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CALGN( bge 11b )
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16: add r1, r1, #(\pull / 8)
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b 8b
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.endm
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backward_copy_shift push=8 pull=24
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17: backward_copy_shift push=16 pull=16
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18: backward_copy_shift push=24 pull=8
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