forked from M-Labs/nac3
Exception handling: copied eh_artiq from current artiq firmware.
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// Portions of the code in this file are derived from code by:
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//
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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![allow(private_no_mangle_fns, non_camel_case_types)]
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use core::{ptr, mem};
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use cslice::CSlice;
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use unwind as uw;
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use libc::{c_int, c_void};
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use eh::dwarf::{self, EHAction};
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type _Unwind_Stop_Fn = extern "C" fn(version: c_int,
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actions: uw::_Unwind_Action,
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exception_class: uw::_Unwind_Exception_Class,
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exception_object: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context,
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stop_parameter: *mut c_void)
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-> uw::_Unwind_Reason_Code;
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extern {
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fn _Unwind_ForcedUnwind(exception: *mut uw::_Unwind_Exception,
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stop_fn: _Unwind_Stop_Fn,
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stop_parameter: *mut c_void) -> uw::_Unwind_Reason_Code;
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}
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#[repr(C)]
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#[derive(Clone, Copy)]
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pub struct Exception<'a> {
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pub name: CSlice<'a, u8>,
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pub file: CSlice<'a, u8>,
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pub line: u32,
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pub column: u32,
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pub function: CSlice<'a, u8>,
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pub message: CSlice<'a, u8>,
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pub param: [i64; 3]
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}
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const EXCEPTION_CLASS: uw::_Unwind_Exception_Class = 0x4d_4c_42_53_41_52_54_51; /* 'MLBSARTQ' */
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const MAX_BACKTRACE_SIZE: usize = 128;
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#[repr(C)]
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struct ExceptionInfo {
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uw_exception: uw::_Unwind_Exception,
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exception: Option<Exception<'static>>,
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handled: bool,
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backtrace: [usize; MAX_BACKTRACE_SIZE],
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backtrace_size: usize
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}
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#[cfg(target_arch = "x86_64")]
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const UNWIND_DATA_REG: (i32, i32) = (0, 1); // RAX, RDX
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#[cfg(any(target_arch = "or1k"))]
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const UNWIND_DATA_REG: (i32, i32) = (3, 4); // R3, R4
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#[export_name="__artiq_personality"]
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pub extern fn personality(version: c_int,
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actions: uw::_Unwind_Action,
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uw_exception_class: uw::_Unwind_Exception_Class,
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uw_exception: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context)
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-> uw::_Unwind_Reason_Code {
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unsafe {
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if version != 1 || uw_exception_class != EXCEPTION_CLASS {
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return uw::_URC_FATAL_PHASE1_ERROR
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}
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let lsda = uw::_Unwind_GetLanguageSpecificData(context) as *const u8;
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let ip = uw::_Unwind_GetIP(context) - 1;
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let func_start = uw::_Unwind_GetRegionStart(context);
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let exception_info = &mut *(uw_exception as *mut ExceptionInfo);
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let exception = &exception_info.exception.unwrap();
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let eh_action = dwarf::find_eh_action(lsda, func_start, ip, exception.name);
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if actions as u32 & uw::_UA_SEARCH_PHASE as u32 != 0 {
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match eh_action {
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EHAction::None |
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EHAction::Cleanup(_) => return uw::_URC_CONTINUE_UNWIND,
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EHAction::Catch(_) => return uw::_URC_HANDLER_FOUND,
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EHAction::Terminate => return uw::_URC_FATAL_PHASE1_ERROR,
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}
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} else {
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match eh_action {
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EHAction::None => return uw::_URC_CONTINUE_UNWIND,
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EHAction::Cleanup(lpad) |
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EHAction::Catch(lpad) => {
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if actions as u32 & uw::_UA_HANDLER_FRAME as u32 != 0 {
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exception_info.handled = true
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}
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// Pass a pair of the unwinder exception and ARTIQ exception
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// (which immediately follows).
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uw::_Unwind_SetGR(context, UNWIND_DATA_REG.0,
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uw_exception as uw::_Unwind_Word);
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uw::_Unwind_SetGR(context, UNWIND_DATA_REG.1,
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exception as *const _ as uw::_Unwind_Word);
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uw::_Unwind_SetIP(context, lpad);
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return uw::_URC_INSTALL_CONTEXT;
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}
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EHAction::Terminate => return uw::_URC_FATAL_PHASE2_ERROR,
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}
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}
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}
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}
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extern fn cleanup(_unwind_code: uw::_Unwind_Reason_Code,
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uw_exception: *mut uw::_Unwind_Exception) {
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unsafe {
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let exception_info = &mut *(uw_exception as *mut ExceptionInfo);
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exception_info.exception = None;
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}
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}
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extern fn uncaught_exception(_version: c_int,
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actions: uw::_Unwind_Action,
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_uw_exception_class: uw::_Unwind_Exception_Class,
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uw_exception: *mut uw::_Unwind_Exception,
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context: *mut uw::_Unwind_Context,
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_stop_parameter: *mut c_void)
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-> uw::_Unwind_Reason_Code {
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unsafe {
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let exception_info = &mut *(uw_exception as *mut ExceptionInfo);
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if exception_info.backtrace_size < exception_info.backtrace.len() {
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let ip = uw::_Unwind_GetIP(context);
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exception_info.backtrace[exception_info.backtrace_size] = ip;
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exception_info.backtrace_size += 1;
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}
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if actions as u32 & uw::_UA_END_OF_STACK as u32 != 0 {
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::terminate(&exception_info.exception.unwrap(),
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exception_info.backtrace[..exception_info.backtrace_size].as_mut())
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} else {
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uw::_URC_NO_REASON
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}
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}
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}
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// We can unfortunately not use mem::zeroed in a static, so Option<> is used as a workaround.
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// See https://github.com/rust-lang/rust/issues/39498.
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static mut INFLIGHT: ExceptionInfo = ExceptionInfo {
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uw_exception: uw::_Unwind_Exception {
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exception_class: EXCEPTION_CLASS,
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exception_cleanup: cleanup,
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private: [0; uw::unwinder_private_data_size],
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},
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exception: None,
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handled: true,
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backtrace: [0; MAX_BACKTRACE_SIZE],
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backtrace_size: 0
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};
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#[export_name="__artiq_raise"]
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#[unwind(allowed)]
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pub unsafe extern fn raise(exception: *const Exception) -> ! {
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// Zing! The Exception<'a> to Exception<'static> transmute is not really sound in case
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// the exception is ever captured. Fortunately, they currently aren't, and we save
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// on the hassle of having to allocate exceptions somewhere except on stack.
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INFLIGHT.exception = Some(mem::transmute::<Exception, Exception<'static>>(*exception));
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INFLIGHT.handled = false;
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let result = uw::_Unwind_RaiseException(&mut INFLIGHT.uw_exception);
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assert!(result == uw::_URC_END_OF_STACK);
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INFLIGHT.backtrace_size = 0;
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let _result = _Unwind_ForcedUnwind(&mut INFLIGHT.uw_exception,
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uncaught_exception, ptr::null_mut());
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unreachable!()
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}
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#[export_name="__artiq_reraise"]
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#[unwind(allowed)]
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pub unsafe extern fn reraise() -> ! {
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use cslice::AsCSlice;
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if INFLIGHT.handled {
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match INFLIGHT.exception {
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Some(ref exception) => raise(exception),
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None => raise(&Exception {
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name: "0:artiq.coredevice.exceptions.RuntimeError".as_c_slice(),
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file: file!().as_c_slice(),
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line: line!(),
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column: column!(),
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// https://github.com/rust-lang/rfcs/pull/1719
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function: "__artiq_reraise".as_c_slice(),
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message: "No active exception to reraise".as_c_slice(),
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param: [0, 0, 0]
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})
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}
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} else {
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uw::_Unwind_Resume(&mut INFLIGHT.uw_exception)
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}
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}
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