235 lines
6.4 KiB
ArmAsm
235 lines
6.4 KiB
ArmAsm
# Copyright (C) 2023-2024 Free Software Foundation, Inc.
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#
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# This file is part of GNU Emacs.
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#
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# GNU Emacs is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published
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# by the Free Software Foundation, either version 3 of the License,
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# or (at your option) any later version.
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#
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# GNU Emacs is distributed in the hope that it will be useful, but
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# 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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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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include(`config-mips.m4')
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.set noreorder # delay slots managed by hand
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.set noat # no assembler macros
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.section .text
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.global __start
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__start:
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dnl li $v0, 5034 # SYS_nanosleep
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dnl dla $a0, .timespec # rqtp
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dnl li $a1, 0 # rmtp
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dnl syscall # syscall
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ld $s2, ($sp) # original stack pointer
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DADDI3( $s0, $sp, 16) # start of load area
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DADDI2( $sp, -16) # primary fd, secondary fd
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li $t0, -1 # secondary fd
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sd $t0, 8($sp) # initialize secondary fd
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.next_action:
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ld $s1, ($s0) # action number
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andi $t0, $s1, 15 # t0 = action number & 15
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beqz $t0, .open_file # open file?
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nop # delay slot
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DADDI2( $t0, -3) # t0 -= 3
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beqz $t0, .rest_of_exec # jump to code
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nop # delay slot
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li $t1, 1
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beq $t0, $t1, .do_mmap_anon # anonymous mmap?
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nop # delay slot
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.do_mmap:
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ld $t0, 8($s0) # vm address
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ld $t1, 16($s0) # file_offset
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ld $t2, 24($s0) # protection
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ld $t3, 32($s0) # length
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ld $v0, 40($s0) # flags
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ld $v1, ($sp) # primary fd
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andi $s3, $s1, 16 # s1 & 16?
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beqz $s3, .do_mmap_1 # secondary fd?
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nop # delay slot
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ld $v1, 8($sp) # secondary fd
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.do_mmap_1:
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move $a0, $t0 # syscall arg
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move $a1, $t3 # syscall arg
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move $a2, $t2 # syscall arg
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move $a3, $v0 # syscall arg
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move $a4, $v1 # syscall arg
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move $a5, $t1 # syscall arg
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li $v0, 5009 # SYS_mmap
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syscall # syscall
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bne $a3, $zero, .perror # perror?
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nop # delay slot
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ld $t1, 48($s0) # clear
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dadd $t0, $a0, $a1 # t0 = end of mapping
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dsub $t1, $t0, $t1 # t1 = t0 - clear
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.align:
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beq $t0, $t1, .continue # already finished
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nop # delay slot
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andi $t2, $t1, 7 # t1 & 7?
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bnez $t2, .filld # start filling longs
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nop # delay slot
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.filld:
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dsub $t2, $t0, $t1 # t2 = t0 - t1
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sltiu $t2, $t2, 64 # t2 < 64?
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bne $t2, $zero, .fillb # fill bytes
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nop # delay slot
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sd $zero, ($t1) # zero doubleword
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DADDI2( $t1, 8) # next doubleword
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sd $zero, ($t1) # zero doubleword
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DADDI2( $t1, 8) # next doubleword
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sd $zero, ($t1) # zero doubleword
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DADDI2( $t1, 8) # next doubleword
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sd $zero, ($t1) # zero doubleword
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DADDI2( $t1, 8) # next doubleword
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sd $zero, ($t1) # zero doubleword
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DADDI2( $t1, 8) # next doubleword
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sd $zero, ($t1) # zero doubleword
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DADDI2( $t1, 8) # next doubleword
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sd $zero, ($t1) # zero doubleword
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DADDI2( $t1, 8) # next doubleword
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sd $zero, ($t1) # zero doubleword
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DADDI2( $t1, 8) # next doubleword
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j .filld # fill either doubleword or byte
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nop # delay slot
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.fillb:
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beq $t0, $t1, .continue # already finished?
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nop # delay slot
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sb $zero, ($t1) # clear byte
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DADDI2( $t1, 1) # t1++
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.continue:
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DADDI2( $s0, 56) # s0 = next action
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j .next_action # next action
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nop # delay slot
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.do_mmap_anon:
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ld $t0, 8($s0) # vm address
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ld $t1, 16($s0) # file_offset
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ld $t2, 24($s0) # protection
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ld $t3, 32($s0) # length
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ld $v0, 40($s0) # flags
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li $v1, -1 # fd
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j .do_mmap_1 # do mmap
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nop # branch delay slot
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.open_file:
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li $v0, 5002 # SYS_open
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DADDI3( $a0, $s0, 8) # start of name
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move $a1, $zero # flags = O_RDONLY
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move $a2, $zero # mode = 0
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syscall # syscall
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bne $a3, $zero, .perror # perror
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nop # delay slot
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DADDI2( $s0, 8) # start of string
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move $t3, $s0 # t3 = s0
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.nextc:
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lb $t0, ($s0) # load byte
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DADDI2( $s0, 1) # s0++
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li $t1, 47 # directory separator `/'
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bne $t0, $t1, .nextc1 # is separator char?
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nop # delay slot
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move $t3, $s0 # t3 = char past separator
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.nextc1:
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bnez $t0, .nextc # next character?
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nop # delay slot
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DADDI2( $s0, 7) # adjust for round
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li $t2, -8 # t2 = -8
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and $s0, $s0, $t2 # mask for round
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andi $t0, $s1, 16 # t1 = s1 & 16
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move $t1, $sp # address of primary fd
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beqz $t0, .primary # primary fd?
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nop # delay slot
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DADDI2( $t1, 8) # address of secondary fd
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sd $v0, ($t1) # store fd
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j .next_action # next action
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nop # delay slot
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.primary:
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sd $v0, ($t1) # store fd
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li $v0, 5153 # SYS_prctl
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li $a0, 15 # PR_SET_NAME
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move $a1, $t3 # char past separator
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move $a2, $zero # a2
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move $a3, $zero # a3
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move $a4, $zero # a4
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move $a5, $zero # a5
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syscall # syscall
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j .next_action # next action
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nop # delay slot
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.perror:
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move $a0, $v0 # errno
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li $v0, 5058 # SYS_exit
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syscall # syscall
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.rest_of_exec:
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move $s1, $s2 # original SP
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ld $t0, ($s1) # argc
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dsll $t0, $t0, 3 # argc *= 8
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DADDI2( $t0, 16) # argc += 16
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dadd $s1, $s1, $t0 # s1 = start of envp
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.skipenv:
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ld $t0, ($s1) # t0 = *s1
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DADDI2( $s1, 8) # s1++
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bne $t0, $zero, .skipenv # skip again
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nop # delay slot
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dla $t3, .auxvtab # address of auxv table
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.one_auxv:
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ld $t0, ($s1) # t0 = auxv type
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li $t1, 10 # t1 = 10
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beqz $t0, .finish # is AT_IGNORE?
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nop # delay slot
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sltu $t1, $t0, $t1 # t1 = t0 < num offsets
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beqz $t1, .next # next auxv
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nop # delay slot
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dsll $t1, $t0, 2 # t1 = t0 * 4
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dadd $t1, $t3, $t1 # t1 = .auxvtab + t1
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lw $t2, ($t1) # t2 = *t1
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beqz $t2, .next # skip auxv
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nop # delay slot
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dadd $t2, $s0, $t2 # t2 = s0 + t2
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ld $t2, ($t2) # t2 = *t2
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sd $t2, 8($s1) # set auxv value
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.next:
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DADDI2( $s1, 16) # next auxv
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j .one_auxv # next auxv
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nop # delay slot
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.finish:
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ld $t0, 8($sp) # secondary fd
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li $t1, -1 # t1 = -1
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ld $s1, ($sp) # s1 = primary fd
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li $v0, 5003 # SYS_close
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beq $t0, $t2, .finish1 # secondary fd set?
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nop # delay slot
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move $a0, $t0 # secondary fd
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syscall # syscall
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li $v0, 5003 # SYS_close
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.finish1:
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move $a0, $s1 # primary fd
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syscall # syscall
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.jump:
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move $v0, $zero # rtld_fini
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ld $t0, 8($s0) # entry
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move $sp, $s2 # restore stack pointer, delay slot
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jr $t0 # enter
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nop # delay slot
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.auxvtab:
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.long 0 # 0
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.long 0 # 1
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.long 0 # 2
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.long 40 # 3 AT_PHDR
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.long 24 # 4 AT_PHENT
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.long 32 # 5 AT_PHNUM
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.long 0 # 6
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.long 48 # 7 AT_BASE
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.long 0 # 8
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.long 16 # 9 AT_ENTRY
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.timespec:
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.quad 10
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.quad 10
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# Local Variables:
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# asm-comment-char: ?#
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# End:
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