C: add static-vs-dynamic-mem-alloc.c

c-programming/experiments/static-vs-dynamic-mem-alloc.c

@@ -0,0 +1,80 @@
+/*
+ * static-vs-dynamic-mem-alloc.c
+ *
+ * Author: Intel A80486DX2-66
+ * License: Creative Commons Zero 1.0 Universal
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#define MULTIPLIER ((size_t) 268435456)
+
+void empty(uint8_t** mem);
+void static_memory_allocation(uint8_t** mem);
+void dynamic_memory_allocation(uint8_t** mem);
+long double measure(void (*function)(uint8_t**), long double* c);
+
+void empty(uint8_t** mem) {
+	return;
+}
+
+void static_memory_allocation(uint8_t** mem) {
+	*mem = malloc(MULTIPLIER * sizeof(uint8_t));
+	if (*mem == NULL) {
+		perror("malloc");
+		exit(EXIT_FAILURE);
+	}
+}
+
+void dynamic_memory_allocation(uint8_t** mem) {
+	*mem = malloc(1 * sizeof(uint8_t));
+	if (*mem == NULL) {
+		perror("malloc");
+		exit(EXIT_FAILURE);
+	}
+	for (size_t i = 1; i < MULTIPLIER; i++) {
+		uint8_t* new_memory = realloc(*mem, i * sizeof(uint8_t));
+		if (new_memory == NULL) {
+			perror("realloc");
+			exit(EXIT_FAILURE);
+		}
+		*mem = new_memory;
+	}
+}
+
+long double measure(void (*function)(uint8_t**), long double* c) {
+	clock_t start;
+
+	start = clock();
+
+	uint8_t* ptr = NULL;
+	function(&ptr);
+	if (ptr != NULL)
+		free(ptr);
+
+	clock_t end = clock();
+	long double cpu_time_used = ((long double) (end - start) * 1000000000.l) /
+	                            CLOCKS_PER_SEC;
+
+	if (c != NULL) {
+		cpu_time_used -= *c;
+		printf(": ~%.0Lf nanoseconds\n", cpu_time_used);
+	}
+	return cpu_time_used;
+}
+
+int main(void) {
+	long double c = measure(empty, NULL); // empty function call
+
+	printf(" Static memory allocation");
+	long double value1 = measure(static_memory_allocation, &c);
+	printf("Dynamic memory allocation");
+	long double value2 = measure(dynamic_memory_allocation, &c);
+	printf("\nStatic memory allocation is ~%.0Lf nanoseconds faster",
+	       value2 - value1);
+
+	return EXIT_SUCCESS;
+}