119 lines
3.7 KiB
C
119 lines
3.7 KiB
C
/*
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* Copyright (c) 2001, 2002, 2009
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* The President and Fellows of Harvard College.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Driver code is in kern/tests/synchprobs.c We will replace that file. This
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* file is yours to modify as you see fit.
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*
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* You should implement your solution to the stoplight problem below. The
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* quadrant and direction mappings for reference: (although the problem is, of
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* course, stable under rotation)
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*
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* |0 |
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* - --
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* 01 1
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* 3 32
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* -- --
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* | 2|
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*
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* As way to think about it, assuming cars drive on the right: a car entering
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* the intersection from direction X will enter intersection quadrant X first.
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* The semantics of the problem are that once a car enters any quadrant it has
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* to be somewhere in the intersection until it call leaveIntersection(),
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* which it should call while in the final quadrant.
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*
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* As an example, let's say a car approaches the intersection and needs to
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* pass through quadrants 0, 3 and 2. Once you call inQuadrant(0), the car is
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* considered in quadrant 0 until you call inQuadrant(3). After you call
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* inQuadrant(2), the car is considered in quadrant 2 until you call
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* leaveIntersection().
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*
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* You will probably want to write some helper functions to assist with the
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* mappings. Modular arithmetic can help, e.g. a car passing straight through
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* the intersection entering from direction X will leave to direction (X + 2)
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* % 4 and pass through quadrants X and (X + 3) % 4. Boo-yah.
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*
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* Your solutions below should call the inQuadrant() and leaveIntersection()
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* functions in synchprobs.c to record their progress.
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*/
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#include <types.h>
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#include <lib.h>
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#include <thread.h>
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#include <test.h>
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#include <synch.h>
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/*
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* Called by the driver during initialization.
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*/
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void
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stoplight_init() {
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return;
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}
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/*
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* Called by the driver during teardown.
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*/
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void stoplight_cleanup() {
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return;
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}
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void
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turnright(uint32_t direction, uint32_t index)
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{
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(void)direction;
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(void)index;
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/*
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* Implement this function.
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*/
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return;
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}
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void
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gostraight(uint32_t direction, uint32_t index)
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{
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(void)direction;
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(void)index;
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/*
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* Implement this function.
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*/
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return;
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}
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void
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turnleft(uint32_t direction, uint32_t index)
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{
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(void)direction;
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(void)index;
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/*
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* Implement this function.
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*/
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return;
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}
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