source: rtems/cpukit/score/cpu/riscv/riscv-context-initialize.c @ 11ff3a9

/*
 *
 * Copyright (c) 2015 University of York.
 * Hesham Almatary <hesham@alumni.york.ac.uk>
 *
 * COPYRIGHT (c) 1989-2006.
 * On-Line Applications Research Corporation (OAR).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <string.h>

#include <rtems/score/cpu.h>
#include <rtems/score/riscv-utility.h>
#include <rtems/score/interr.h>

void _CPU_Context_Initialize(
  Context_Control *context,
  void *stack_area_begin,
  size_t stack_area_size,
  unsigned long new_level,
  void (*entry_point)( void ),
  bool is_fp,
  void *tls_area
)
{
  uintptr_t stack = ((uintptr_t) stack_area_begin);

  /* Account for red-zone */
  uintptr_t stack_high = stack + stack_area_size - RISCV_GCC_RED_ZONE_SIZE;

  memset(context, 0, sizeof(*context));

  /* Stack Pointer - sp/x2 */
  context->x[2] = stack_high;
  /* Frame Pointer - fp/x8 */
  context->x[8] = stack_high;
  /* Return Address - ra/x1 */
  context->x[1] = (uintptr_t) entry_point;

  /* Enable interrupts and FP */
  context->mstatus = MSTATUS_FS | MSTATUS_MIE;
}