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119 lines
1.7 KiB
119 lines
1.7 KiB
/*
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* strcmp for ARMv6-M (optimized for performance, not size)
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*
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* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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* See https://llvm.org/LICENSE.txt for license information.
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* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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*/
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#if __ARM_ARCH == 6 && __ARM_ARCH_6M__ >= 1
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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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ENTRY_ALIGN (__strcmp_armv6m, 4)
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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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END (__strcmp_armv6m)
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#endif /* __ARM_ARCH == 6 && __ARM_ARCH_6M__ >= 1 */
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