fa322155ad
* exec/Makefile.in (is_mips): New substitution. (.s.o): Avoid calling m4 unless it be set. * exec/configure.ac: Substitute is_mips, and don't generate config-mips.m4 otherwise. * exec/loader-x86.s: * exec/loader-x86_64.s: Use assembler rather than m4-defined comment syntax.
192 lines
4.7 KiB
ArmAsm
192 lines
4.7 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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.section .text
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.global _start
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_start:
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# movq $35, %rax # SYS_nanosleep
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# leaq timespec(%rip), %rdi
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# xorq %rsi, %rsi
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# syscall
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popq %r13 # original SP
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popq %r15 # size of load area.
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movq $-1, %r12 # r12 is the interpreter fd
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.next_action:
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movq (%rsp), %r14 # action number
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movq %r14, %r15 # original action number
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andq $-17, %r14
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cmpq $0, %r14 # open file?
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je .open_file
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cmpq $3, %r14 # jump?
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je .rest_of_exec
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cmpq $4, %r14 # anonymous mmap?
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je .do_mmap_anon
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.do_mmap:
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movq $9, %rax # SYS_mmap
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movq 8(%rsp), %rdi # address
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movq 16(%rsp), %r9 # offset
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movq 24(%rsp), %rdx # protection
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movq 32(%rsp), %rsi # length
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movq 40(%rsp), %r10 # flags
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# set r8 to the primary fd unless r15 & 16
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testq $16, %r15
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movq %r12, %r8
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cmovzq %rbx, %r8
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.do_mmap_1:
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syscall
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cmpq $-1, %rax # mmap failed
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je .perror
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movq 48(%rsp), %r9 # clear
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testq %r9, %r9
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jz .continue
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movq 8(%rsp), %r10 # start of mapping
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addq 32(%rsp), %r10 # end of mapping
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subq %r9, %r10 # start of clear area
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.again:
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testq %r9, %r9
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jz .continue
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subq $1, %r9
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movb $0, (%r10, %r9, 1)
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jmp .again
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.continue:
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leaq 56(%rsp), %rsp
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jmp .next_action
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.do_mmap_anon:
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movq $9, %rax # SYS_mmap
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movq 8(%rsp), %rdi # address
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movq 16(%rsp), %r9 # offset
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movq 24(%rsp), %rdx # protection
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movq 32(%rsp), %rsi # length
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movq 40(%rsp), %r10 # flags
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movq $-1, %r8 # -1
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jmp .do_mmap_1
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.open_file:
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movq $2, %rax # SYS_open
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leaq 8(%rsp), %rdi # rdi = %rsp + 8
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xorq %rsi, %rsi # flags = O_RDONLY
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xorq %rdx, %rdx # mode = 0
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syscall
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cmpq $-1, %rax # open failed
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jle .perror
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movq %rdi, %rsp # rsp = start of string
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subq $1, %rsp
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movq %rsp, %r14 # r14 = start of string
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.nextc:
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addq $1, %rsp
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movb (%rsp), %dil # rdi = *rsp
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cmpb $47, %dil # *rsp == '/'?
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jne .nextc1
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movq %rsp, %r14 # r14 = rsp
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addq $1, %r14 # r14 = char past separator
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.nextc1:
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cmpb $0, %dil # *rsp == 0?
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jne .nextc
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addq $8, %rsp # adjust past rsp prior to rounding
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andq $-8, %rsp # round rsp up to the next quad
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testq $16, %r15 # r15 & 16?
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jz .primary
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movq %rax, %r12 # otherwise, move fd to r12
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jmp .next_action
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.primary:
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movq %rax, %rbx # if not, move fd to rbx
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movq $157, %rax # SYS_prctl
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movq $15, %rdi # PR_SET_NAME
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movq %r14, %rsi # arg1
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xorq %rdx, %rdx # arg2
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xorq %r10, %r10 # arg3
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xorq %r8, %r8 # arg4
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xorq %r9, %r9 # arg5
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syscall
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jmp .next_action
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.perror:
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movq %rax, %r12 # error code
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negq %r12
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movq $1, %rax # SYS_write
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movq $1, %rdi # stdout
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leaq error(%rip), %rsi # buffer
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movq $23, %rdx # count
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syscall
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movq $60, %rax # SYS_exit
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movq %r12, %rdi # code
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syscall
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.rest_of_exec: # rsp now points to six quads:
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movq %rsp, %r8 # now, they are r8
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movq %r13, %rsp # restore SP
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popq %r10 # argc
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leaq 8(%rsp,%r10,8), %rsp # now at start of environ
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.skip_environ:
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popq %r10 # envp[N]
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testq %r10, %r10 # envp[n]?
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jnz .skip_environ # otherwise, rsp is now at the start of auxv
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.one_auxv:
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popq %rcx # auxv type
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addq $8, %rsp # skip value
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testq %rcx, %rcx # is 0?
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jz .cleanup
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cmpq $3, %rcx # is AT_PHDR?
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je .replace_phdr
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cmpq $4, %rcx # is AT_PHENT?
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je .replace_phent
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cmpq $5, %rcx # is AT_PHNUM?
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je .replace_phnum
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cmpq $9, %rcx # is AT_ENTRY?
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je .replace_entry
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cmpq $7, %rcx # is AT_BASE?
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je .replace_base
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jmp .one_auxv
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.replace_phdr:
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movq 40(%r8), %r9
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movq %r9, -8(%rsp) # set at_phdr
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jmp .one_auxv
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.replace_phent:
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movq 24(%r8), %r9
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movq %r9, -8(%rsp) # set at_phent
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jmp .one_auxv
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.replace_phnum:
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movq 32(%r8), %r9
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movq %r9, -8(%rsp) # set at_phnum
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jmp .one_auxv
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.replace_entry:
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movq 16(%r8), %r9
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movq %r9, -8(%rsp) # set at_entry
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jmp .one_auxv
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.replace_base:
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movq 48(%r8), %r9
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movq %r9, -8(%rsp) # set at_base
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jmp .one_auxv
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.cleanup:
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movq $3, %rax # SYS_close
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cmpq $-1, %r12 # see if interpreter fd is set
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je .cleanup_1
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movq %r12, %rdi
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syscall
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movq $3, %rax # SYS_close
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.cleanup_1:
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movq %rbx, %rdi
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syscall
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.enter:
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pushq $0
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popfq # clear FP state
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movq %r13, %rsp # restore SP
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xorq %rdx, %rdx # clear rtld_fini
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jmpq *8(%r8) # entry
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error:
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.ascii "_start: internal error."
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timespec:
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.quad 10
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.quad 10
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