CS3413/Assignment6/code/main.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>

// 1 - best fit
// 2 - worst fit
// 3 - first fit
enum Algorithm {
	BEST_FIT = 1,
	WORST_FIT = 2,
	FIRST_FIT = 3
};
enum Algorithm algorithm;
int memSize;
int totalAllocated = 0;
int totalMemAllocated = 0;
int totalFailed = 0;
int totalTerminated = 0;
int totalFreedMemory = 0;

int *memory;

void allocateByIndex(int index, int howMuchToAllocate, int processId) {
	for (int i = index; i < index + howMuchToAllocate; ++i) {
		memory[i] = processId;
		// Statistics
		totalMemAllocated++;
	}
}

bool doAllocate(int howMuchToAllocate, int processId) {
	int FirstFitIndex = -1;
	int WorstFitIndex = -1;
	int BestFitIndex = -1;
	int startIndex = -1;

	int size = 0;

	int smallestSoFar = memSize;
	int biggestSoFar = 0;
	for (int i = 0; i < memSize; ++i) {
		if (memory[i] == 0) {
			if (size == 0) {
				startIndex = i;
			}
			size++;
		} else {
			if (size >= howMuchToAllocate) {
				// On first fit, set the start index
				if (FirstFitIndex == -1) {
					FirstFitIndex = startIndex;
				}
				// If the size of the contiguous empty memory is bigger than the largest contiguous empty memory so far, set the index and update the size
				if (size > biggestSoFar) {
					WorstFitIndex = startIndex;
					biggestSoFar = size;
				}
				// If the size of the contiguous empty memory is smaller than the smallest contiguous empty memory so far, set the index and update the size
				if (size > 0 && smallestSoFar > size) {
					BestFitIndex = startIndex;
					smallestSoFar = size;
				}
			}
			size = 0;
			startIndex = -1;
		}
	}
	// Check if the last chunk is the first fit
	if (FirstFitIndex == -1 && size >= howMuchToAllocate) {
		FirstFitIndex = startIndex;
	}

	// Check if the last chunk is the smallest
	if (size > 0 && smallestSoFar >= size) {
		BestFitIndex = startIndex;
	}
	// Check if the last chunk is the biggest
	if (size >= biggestSoFar) {
		WorstFitIndex = startIndex;
	}

	// Since first fit is always set if there is space, we can error on that for any algorithm
	if (FirstFitIndex == -1 || howMuchToAllocate > memSize) {
		printf("Process %d failed to allocate %d memory\n", processId, howMuchToAllocate);
		// Statistics
		totalFailed++;

		// Early exit because there is no space, so don't touch memory
		return false;
	}

	switch (algorithm) {
		case BEST_FIT: {
			allocateByIndex(BestFitIndex, howMuchToAllocate, processId);
			break;
		}
		case WORST_FIT: {
			allocateByIndex(WorstFitIndex, howMuchToAllocate, processId);
			break;
		}
		case FIRST_FIT: {
			allocateByIndex(FirstFitIndex, howMuchToAllocate, processId);
			break;
		}
		default: {
			printf("There was an error, the algorithm is uninitialized");
			exit(0);
		}
	}
	// Statistics
	totalAllocated++;
	return true;
}

bool doFree(int processId) {
	bool found = false;
	for (int i = 0; i < memSize; ++i) {
		if (memory[i] == processId) {
			memory[i] = 0;
			found = true;
			// Statistics
			totalFreedMemory++;
		}
	}
	if (found) {
		// Statistics
		totalTerminated++;

	} else {
		printf("Process %d failed to free memory\n", processId);
		// Statistics
		// Might not need to be counted as a failed request?
		totalFailed++;
	}
	return found;
}

int calcFinalMemory() {
	int total = 0;
	for (int i = 0; i < memSize; ++i) {
		if (memory[i] == 0) {
			total++;
		}
	}
	return total;
}

int getNumberOfChunks() {
	int total = 0;
	bool inChunk = false;
	for (int i = 0; i < memSize; ++i) {
		if (memory[i] == 0) {
			if (!inChunk) {
				inChunk = true;
				total++;
			}
		} else {
			inChunk = false;
		}
	}
	return total;
}

int getSmallest() {
	int smallestSize = memSize;
	int size = 0;
	for (int i = 0; i < memSize; ++i) {
		if (memory[i] == 0) {
			size++;
		} else if (smallestSize > size && size != 0) {
			smallestSize = size;
			size = 0;
		}
	}
	// Check if the last chunk is the smallest
	if (smallestSize >= memSize) {
		smallestSize = size;
	}
	return smallestSize;
}

int getBiggest() {
	int biggestSize = 0;
	int size = 0;
	for (int i = 0; i < memSize; ++i) {
		if (memory[i] == 0) {
			size++;
		} else if (size > biggestSize) {
			biggestSize = size;
			size = 0;
		}
	}
	// Check if the last chunk is the biggest
	if (biggestSize <= size) {
		biggestSize = size;
	}
	return biggestSize;
}

int main(int argc, char **argv) {
	for (int i = 0; i < argc; i++) {
		if (strcmp(argv[i], "-b") == 0) {
			algorithm = BEST_FIT;
		} else if (strcmp(argv[i], "-w") == 0) {
			algorithm = WORST_FIT;
		} else if (strcmp(argv[i], "-s") == 0) {
			memSize = atoi(argv[i + 1]);
		} else if (strcmp(argv[i], "-f") == 0) {
			algorithm = FIRST_FIT;
		}
	}
	if (memSize >= 0) {
		// Use calloc to initialize memory to 0, which means empty in our case
		memory = calloc(memSize, sizeof(int));
	} else {
		printf("The program requires size\n");
		exit(0);
	}
	char operation;
	int id = 1337;
	int size;
	while (EOF != scanf("%c", &operation)) {
		switch (operation) {
			case 'N':
				scanf(" %d %d\n", &id, &size);
				doAllocate(size, id);
				break;
			case 'T':
				scanf(" %d\n", &id);
				doFree(id);
				break;
			case 'S':
				printf("Total Processes created %d, Total allocated memory %d, Total Processes\n"
					   "terminated %d, Total freed memory %d, Final memory available %d, Final\n"
					   "smallest and largest fragmented memory sizes %d and %d, total failed requests:%d, number of memory chunks: %d\n",
					   totalAllocated, totalMemAllocated,
					   totalTerminated, totalFreedMemory, calcFinalMemory(),
					   getSmallest(), getBiggest(), totalFailed, getNumberOfChunks());
				break;
		}
	}
	// Free the memory, just for good measure
	free(memory);
	return 0;
}