/* SPDX-License-Identifier: BSD-3-Clause */
/*
 * Authors: Santiago Pagani <santiagopagani@gmail.com>
 *
 * Copyright (c) 2020, NEC Laboratories Europe GmbH, NEC Corporation.
 *                     All rights reserved.
 *
 * 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.
 * 3. Neither the name of the copyright holder nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
 *
 * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
 */

#include <stdint.h>
#include <uk/config.h>

uint64_t computeUsedStack(void) {
#if CONFIG_RASPI_WATERMARK_STACK
	#define MAX_ADDRESS	0x80000
	#define STACK_START	0
	#define STACK_SIZE	(MAX_ADDRESS - STACK_START)
	void *address = (void *)(STACK_SIZE/2 + STACK_START);
	unsigned int step = STACK_SIZE/4;

	while (step >= 8) {
		uint64_t expectedValue = ((MAX_ADDRESS - (uint64_t)address) >> 3);
		uint64_t readValue = (uint64_t)*((volatile uint64_t *)address);

		if (expectedValue == readValue) {
			address = (void *)((uint64_t)address + step);
		} else {
			address = (void *)((uint64_t)address - step);
		}
		step >>= 1;
	}
	
	return MAX_ADDRESS - (uint64_t)address;
#else
	return 0;
#endif
}