sw/device/lib/runtime/hart.c

// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

#include "sw/device/lib/runtime/hart.h"

#include <stdbool.h>

#include "sw/device/lib/arch/device.h"
#include "sw/device/lib/base/math.h"
#include "sw/device/lib/runtime/ibex.h"

void busy_spin_micros(uint32_t usec) {
  uint64_t start = ibex_mcycle_read();
  // uint64_t cycles = udiv64_slow(kClockFreqCpuHz * usec, 1000000, NULL);
  //
  // Some tests on Verilator are sufficiently time-sensitive that generalized
  // slow division can cause tests to time out (e.g. uncessary watchdog bites.
  //
  // So, instead, we divide by 2^20 = 1048576 via a shift, which is
  // conveniently almost a million.
  uint64_t cycles = (kClockFreqCpuHz * usec) >> 20;
  while ((ibex_mcycle_read() - start) < cycles) {
  }
}

noreturn void abort(void) {
  while (true) {
    wait_for_interrupt();
  }
}

// `extern` declarations to give the inline functions in the
// corresponding header a link location.

extern void wait_for_interrupt(void);