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//------------------------------------------------------------------------
// sysfutex_d tests basic functionalities of futex system call:
//    - make a thread wait on a variable
//    - wake up a thread waiting on a variable
//------------------------------------------------------------------------

#include "riscv_test.h"
#include "test_macros.h"
#include "test_macros_mt_ecall.h"

  RVTEST_RV64U
  RVTEST_CODE_BEGIN

#define NUM_THREADS 1
#define LOOP_COUNT  1000

//------------------------------------------------------------------------
// Master thread creates new threads, call _master function, waits for all
// threads to complete, deallocates threads and checks result
//------------------------------------------------------------------------
  li      a0, NUM_THREADS
  call    _create_threads

  la      t6, n_worker_threads
  ld      a0, (t6)
  beqz    a0, _fail        // exit if there's no worker thread
  call    _master_work

  la      t6, n_worker_threads
  ld      a0, (t6)
  call    _join

  la      t6, n_worker_threads
  ld      a0, (t6)
  call    _check

  la      t6, n_worker_threads
  ld      a0, (t6)
  call    _delete_threads

  li      a0, SUCCESS

  RVTEST_CODE_END

//------------------------------------------------------------------------
// master_work function executed by the parent/master thread
//
//    Wake up thread(s) waiting on futex_X and then wait on futex_Y in a
//    loop.
//------------------------------------------------------------------------
_master_work:
  mv    s0, ra                  // save return address
  li    t0, LOOP_COUNT
  la    t1, count_master

1:
  // futex(futex_X, FUTEX_WAKE_PRIVATE, 1)
  la    a0, futex_X
  li    a1, FUTEX_WAKE_PRIVATE
  li    a2, 1                   // wake up at most 1 thread
  li    a7, SYSCALL_FUTEX
  ecall

  // keep waking up until at least one thread is waken up
  beqz  a0, 1b

  // increment count_master
  ld    t2, (t1)
  addi  t2, t2, 1
  sd    t2, (t1)

  // futex(futex_Y, FUTEX_WAIT_PRIVATE, 0)
  la    a0, futex_Y
  li    a1, FUTEX_WAIT_PRIVATE
  li    a2, 0                   // expected val of futex_Y
  li    a7, SYSCALL_FUTEX
  ecall

  // decrement t0
  addi  t0, t0, -1
  bnez  t0, 1b

  // restore return address and return
  mv    ra, s0
  ret

//------------------------------------------------------------------------
// mt_test function executed by child threads
//
//    Wait on futex_X and then wake up threads waiting on futex_Y in a loop
//------------------------------------------------------------------------
_mt_test:
  li    t0, LOOP_COUNT
  la    t1, count_child

1:
  // futex(futex_X, FUTEX_WAIT_PRIVATE, 1)
  la    a0, futex_X
  li    a1, FUTEX_WAIT_PRIVATE
  li    a2, 0                   // expected val of futex_X
  li    a7, SYSCALL_FUTEX
  ecall

  // increment count_child
  ld    t2, (t1)
  addi  t2, t2, 1
  sd    t2, (t1)

2:
  // futex(futex_Y, FUTEX_WAKE_PRIVATE, 0)
  la    a0, futex_Y
  li    a1, FUTEX_WAKE_PRIVATE
  li    a2, 1                   // wake up at most 1 thread
  li    a7, SYSCALL_FUTEX
  ecall

  // keep waking up until at least one thread is waken up
  beqz  a0, 2b

  // decrement t0
  addi  t0, t0, -1
  bnez  t0, 1b

  RVTEST_CODE_END

//------------------------------------------------------------------------
// _check:
//    Each thread should do LOOP_COUNT iterations
//------------------------------------------------------------------------

_check:
  la    t0, count_master
  la    t1, count_child
  li    t2, LOOP_COUNT

  ld    t0, (t0)
  bne   t0, t2, _fail

  ld    t1, (t1)
  bne   t1, t2, _fail

  ret

_fail:
  li        a0, FAILURE
  RVTEST_CODE_END

  .data

futex_X:  .dword  0
futex_Y:  .dword  0

count_master:   .dword  0
count_child:    .dword  0

MT_DATA