144 lines
No EOL
3.8 KiB
C
144 lines
No EOL
3.8 KiB
C
/*----------------------------------------------------------
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* HTBLA-Leonding / Class: 2IHIF
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* ---------------------------------------------------------
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* Exercise Number: 09
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* Title: Tower of Hanoi Disk ADT implementation
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* Author: Marc Tismonar
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* ----------------------------------------------------------
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* Description:
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* Implementation of toh_board.h.
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* ----------------------------------------------------------
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*/
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#include "toh_board.h"
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#include "config.h"
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#include "toh_disk.h"
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#include <stdlib.h>
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#ifdef NULL
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#undef NULL
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#define NULL ((void *)0)
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#endif
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/** Abstraction of a rod type */
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/* Hint: Define a type 'Rod' as a pointer to Disk
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for usage in exchange with Disk array */
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struct TohBoardData {
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Rod rods[3][MAX_DISKS];
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};
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static TohBoard static_board = NULL;
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/**
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* Provides the instance of the 'Tower of Hanoi' board.
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* Exactly one instance is supported.
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*
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* @return TohBoard The board instance.
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*/
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TohBoard tb_get_board() {
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if (tb_is_valid(static_board)) {
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return static_board;
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}
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static_board = (TohBoard)calloc(sizeof(struct TohBoardData), 1);
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return static_board;
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}
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/**
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* Removes all disks from any rod of the given board.
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*
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* @param board The board instance in focus.
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*/
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void tb_clear_board(TohBoard board) {
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for (int i = 0; i < 3; i++) {
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for (int j = 0; j < MAX_DISKS; j++) {
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board->rods[i][j] = NULL;
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}
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}
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}
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/**
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* Determines whether or not the given board is valid.
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* A board is NOT valid, if it is 0.
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*
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* @param board The board to evaluate.
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* @return If the given board is valid, false otherwise.
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*/
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bool tb_is_valid(TohBoard board) {
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return board != NULL;
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}
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/**
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* Provides the top-most disk of the given rod and removes it from this rod.
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*
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* @param board The board instance in focus.
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* @param rodName The rod from which the disk shall be taken and removed.
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* @return The removed disk or 0, if no disk was on the rod.
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*/
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Disk tb_pop_disk(TohBoard board, RodName rodName) {
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if (!tb_is_valid(board)) {
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return NULL;
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}
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Disk disk = NULL;
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for (int i = MAX_DISKS - 1; i >= 0; i--) {
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if (board->rods[rodName][i] != NULL) {
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disk = board->rods[rodName][i];
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board->rods[rodName][i] = NULL;
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break;
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}
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}
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return disk;
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}
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/**
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* Applies the given disk to the given rod, if this
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* is allowed according to the rules.
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*
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* @param board The board instance in focus.
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* @param rodName The rod on which the disk shall be placed.
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* @param disk The disk to place on the rod.
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* @return True if the disk could be legally placed on the rod
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* (move is allowed and disk is valid), false otherwise.
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*/
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bool tb_push_disk(TohBoard board, RodName rodName, Disk disk) {
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if (!tb_is_valid(board) || !td_is_valid(disk)) {
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return false;
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}
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for (int i = 0; i < MAX_DISKS; i++) {
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if (board->rods[rodName][i] == NULL) {
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// Check if it is at the bottom or if the it is smaller than the one below
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if (i > 0 && !td_is_smaller(board->rods[rodName][i - 1], disk)) {
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return false;
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}
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board->rods[rodName][i] = disk;
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return true;
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}
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}
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return false;
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}
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/**
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* Provides the disk from the named rod at the given position.
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*
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* @param board The board instance in focus.
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* @param rodName The rod on which the disk shall be placed.
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* @param idx The index of the desired disk on the named rod.
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* Index 0 addresses the bottom-most disk.
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* @return The addressed disk or 0, if not disk is located on the
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* index position of the named rod.
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*/
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Disk tb_get_disk(TohBoard board, RodName rodName, unsigned short idx) {
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if (!tb_is_valid(board) || idx >= MAX_DISKS) {
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return NULL;
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}
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// no need to check, as everything is going to be initalized with 0
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return board->rods[rodName][idx];
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} |