143 lines
2.9 KiB
ArmAsm
143 lines
2.9 KiB
ArmAsm
/* The assembly function for memory compare. C-SKY ABIV2 version.
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Copyright (C) 2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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ENTRY (memcmp)
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/* Test if len less than 4 bytes. */
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mov r3, r0
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movi r0, 0
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mov r12, r4
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cmplti r2, 4
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jbt .L_compare_by_byte
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andi r13, r0, 3
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movi r19, 4
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/* Test if s1 is not 4 bytes aligned. */
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bnez r13, .L_s1_not_aligned
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LABLE_ALIGN
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.L_s1_aligned:
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/* If dest is aligned, then copy. */
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zext r18, r2, 31, 4
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/* Test if len less than 16 bytes. */
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bez r18, .L_compare_by_word
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.L_compare_by_4word:
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/* If aligned, load word each time. */
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ldw r20, (r3, 0)
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ldw r21, (r1, 0)
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/* If s1[i] != s2[i], goto .L_byte_check. */
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cmpne r20, r21
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bt .L_byte_check
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ldw r20, (r3, 4)
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ldw r21, (r1, 4)
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cmpne r20, r21
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bt .L_byte_check
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ldw r20, (r3, 8)
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ldw r21, (r1, 8)
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cmpne r20, r21
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bt .L_byte_check
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ldw r20, (r3, 12)
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ldw r21, (r1, 12)
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cmpne r20, r21
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bt .L_byte_check
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PRE_BNEZAD (r18)
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addi a3, 16
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addi a1, 16
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BNEZAD (r18, .L_compare_by_4word)
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.L_compare_by_word:
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zext r18, r2, 3, 2
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bez r18, .L_compare_by_byte
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.L_compare_by_word_loop:
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ldw r20, (r3, 0)
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ldw r21, (r1, 0)
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addi r3, 4
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PRE_BNEZAD (r18)
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cmpne r20, r21
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addi r1, 4
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bt .L_byte_check
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BNEZAD (r18, .L_compare_by_word_loop)
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.L_compare_by_byte:
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zext r18, r2, 1, 0
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bez r18, .L_return
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.L_compare_by_byte_loop:
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ldb r0, (r3, 0)
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ldb r4, (r1, 0)
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addi r3, 1
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subu r0, r4
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PRE_BNEZAD (r18)
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addi r1, 1
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bnez r0, .L_return
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BNEZAD (r18, .L_compare_by_byte_loop)
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.L_return:
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mov r4, r12
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rts
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/* s1[i] != s2[i] in word, so we check byte 3. */
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.L_byte_check:
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xtrb3 r0, r20
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xtrb3 r2, r21
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subu r0, r2
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bnez r0, .L_return
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/* check byte 2 */
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xtrb2 r0, r20
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xtrb2 r2, r21
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subu r0, r2
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bnez r0, .L_return
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/* check byte 1 */
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xtrb1 r0, r20
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xtrb1 r2, r21
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subu r0, r2
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bnez r0, .L_return
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/* check byte 0 */
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xtrb0 r0, r20
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xtrb0 r2, r21
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subu r0, r2
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br .L_return
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/* Compare when s1 is not aligned. */
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.L_s1_not_aligned:
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sub r13, r19, r13
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sub r2, r13
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.L_s1_not_aligned_loop:
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ldb r0, (r3, 0)
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ldb r4, (r1, 0)
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addi r3, 1
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subu r0, r4
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PRE_BNEZAD (r13)
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addi r1, 1
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bnez r0, .L_return
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BNEZAD (r13, .L_s1_not_aligned_loop)
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br .L_s1_aligned
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END (memcmp)
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weak_alias (memcmp, bcmp)
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libc_hidden_def (memcmp)
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.weak memcmp
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