Added OS II assignments

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 1/main.c

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+/* 
+ * File:   main.c
+ * Author: caperren
+ *
+ * Created on April 13, 2018, 7:27 PM
+ */
+
+/*
+ * Important implementation notes...
+ * Consumer prints out number in struct on consumption
+ * Timeout is how long before consumer is done with item (2-7 seconds)
+ * Producer waits 3-7 seconds
+ * Max buffer size is 32
+ * Consumer/s and producer need lock on buffer when doing things
+ * If nothing in queue, consumer blocks until there is
+ */
+
+#include "mt19937ar.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+
+// Program defines you might want to change
+#define MAX_BUFFER_SIZE 32
+
+#define MIN_RANDOM_PRODUCER 3
+#define MAX_RANDOM_PRODUCER 7
+
+#define MIN_RANDOM_CONSUMER 2
+#define MAX_RANDOM_CONSUMER 9
+
+//RDRAND value to check for
+#define RDRAND_FLAG (1 << 30)
+
+// Data structure for the buffer elements
+struct two_values {
+    uint8_t number;
+    uint8_t work_timeout;
+};
+
+//Storage containers and mutex for access
+struct two_values storage_buffer[MAX_BUFFER_SIZE];
+uint16_t tasks_in_buffer = 0;
+
+pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+
+// Get random number based on whether rdrand is supported.
+uint8_t get_random_number(uint8_t min, uint8_t max) {
+    uint8_t rand_val;
+    unsigned long seed;
+
+    unsigned int eax;
+    unsigned int ebx;
+    unsigned int ecx;
+    unsigned int edx;
+
+    eax = 0x01;
+
+    // ASM for checking if RDRAND supported
+    __asm__ __volatile__("cpuid"
+            : "=a" (eax),
+            "=b" (ebx),
+            "=c" (ecx),
+            "=d" (edx)
+            : "a" (1),
+            "c" (0)
+            );
+
+    // Seed random with /dev/random
+    int random = open("/dev/random", O_RDONLY);
+    read(random, &seed, sizeof (seed));
+
+    unsigned int random_value;
+
+    if ((ecx & RDRAND_FLAG) == RDRAND_FLAG) {
+	char return_code = 0;
+	char count = 0;
+
+        // ASM for RDRAND
+	while(return_code != 1 && count < 10){
+		__asm__ volatile(
+		        "rdrand %0 ; setc %1"
+		        : "=r" (random_value), "=qm" (return_code)
+		);
+
+		count++;
+	}
+    } else {
+        // Twister if RDRAND not supported
+        init_genrand(seed);
+	random_value = genrand_int32();
+    }
+
+    return (random_value % (max + 1 - min)) + min;
+}
+
+void *consume_buffer_items(){
+    uint8_t number;
+    uint8_t work_timeout;
+    
+    while(1){
+        // This waits for a task to exist, then makes a temporary copy
+        // of the data in the last item in the queue.
+        // It then removes the item, while mutex locking during all of this
+        while(tasks_in_buffer == 0);
+        pthread_mutex_lock(&mutex);
+        
+        number = storage_buffer[tasks_in_buffer - 1].number;
+        work_timeout = storage_buffer[tasks_in_buffer - 1].work_timeout;
+        storage_buffer[tasks_in_buffer - 1].number = 0;
+        storage_buffer[tasks_in_buffer - 1].work_timeout = 0;
+        tasks_in_buffer--;
+        
+        pthread_mutex_unlock(&mutex);
+        
+        printf("Consumer found number: %u. Now waiting %u seconds.\n", number, work_timeout);
+        fflush(stdout);
+        
+        sleep(work_timeout);   
+    }
+    
+}
+
+int main(int argc, char **argv) {  
+    pthread_t consumer_thread;
+    
+    // This makes the consumer thread
+    if(pthread_create(&consumer_thread, NULL, consume_buffer_items, NULL)) {
+        fprintf(stderr, "Error creating thread\n");
+        return 1;
+    }
+    
+    //Zero out array
+    for(uint16_t i = 0 ; i < MAX_BUFFER_SIZE ; i++){
+        storage_buffer[i].number = 0;
+        storage_buffer[i].work_timeout = 0;
+    }
+    
+    uint8_t number;
+    uint8_t work_timeout;
+    uint8_t producer_sleep;
+    
+    while(1){
+        // This generates values for a new buffer element, waits until theres
+        // space in the buffer, then adds and item to the buffer
+        number = get_random_number(0, UINT8_MAX);
+        work_timeout = get_random_number(MIN_RANDOM_CONSUMER, MAX_RANDOM_CONSUMER);
+        producer_sleep = get_random_number(MIN_RANDOM_PRODUCER, MAX_RANDOM_PRODUCER);
+        
+        while(tasks_in_buffer == MAX_BUFFER_SIZE);
+        
+        pthread_mutex_lock(&mutex);
+        storage_buffer[tasks_in_buffer].number = number;
+        storage_buffer[tasks_in_buffer].work_timeout = work_timeout;
+        tasks_in_buffer++;
+        pthread_mutex_unlock(&mutex);
+        
+        printf("Producer adding number: %u. Consumers's delay will be %u seconds. Producer waiting %u seconds.\n", number, work_timeout, producer_sleep);
+        fflush(stdout);
+        
+        sleep(producer_sleep);
+    }
+
+    return 0;
+}
+

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 1/makefile

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+all: clean build
+	
+clean:
+	rm -f *.o
+	rm -f concurrency1
+	
+build:
+	gcc main.c mt19937ar.h -o concurrency1 -std=c99 -pthread

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 1/mt19937ar.h

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+/* 
+   A C-program for MT19937, with initialization improved 2002/1/26.
+   Coded by Takuji Nishimura and Makoto Matsumoto.
+
+   Before using, initialize the state by using init_genrand(seed)  
+   or init_by_array(init_key, key_length).
+
+   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
+   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. The names of its contributors may not 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 OWNER 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.
+
+
+   Any feedback is very welcome.
+   http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
+   email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
+*/
+
+#include <stdio.h>
+
+/* Period parameters */  
+#define N 624
+#define M 397
+#define MATRIX_A 0x9908b0dfUL   /* constant vector a */
+#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
+#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
+
+static unsigned long mt[N]; /* the array for the state vector  */
+static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
+
+/* initializes mt[N] with a seed */
+void init_genrand(unsigned long s)
+{
+	mt[0]= s & 0xffffffffUL;
+	for (mti=1; mti<N; mti++) {
+		mt[mti] = 
+			(1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti); 
+		/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
+		/* In the previous versions, MSBs of the seed affect   */
+		/* only MSBs of the array mt[].                        */
+		/* 2002/01/09 modified by Makoto Matsumoto             */
+		mt[mti] &= 0xffffffffUL;
+		/* for >32 bit machines */
+	}
+}
+
+/* initialize by an array with array-length */
+/* init_key is the array for initializing keys */
+/* key_length is its length */
+/* slight change for C++, 2004/2/26 */
+void init_by_array(unsigned long init_key[], int key_length)
+{
+	int i, j, k;
+	init_genrand(19650218UL);
+	i=1; j=0;
+	k = (N>key_length ? N : key_length);
+	for (; k; k--) {
+		mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
+			+ init_key[j] + j; /* non linear */
+		mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+		i++; j++;
+		if (i>=N) { mt[0] = mt[N-1]; i=1; }
+		if (j>=key_length) j=0;
+	}
+	for (k=N-1; k; k--) {
+		mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
+			- i; /* non linear */
+		mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+		i++;
+		if (i>=N) { mt[0] = mt[N-1]; i=1; }
+	}
+
+	mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */ 
+}
+
+/* generates a random number on [0,0xffffffff]-interval */
+unsigned long genrand_int32(void)
+{
+	unsigned long y;
+	static unsigned long mag01[2]={0x0UL, MATRIX_A};
+	/* mag01[x] = x * MATRIX_A  for x=0,1 */
+
+	if (mti >= N) { /* generate N words at one time */
+		int kk;
+
+		if (mti == N+1)   /* if init_genrand() has not been called, */
+			init_genrand(5489UL); /* a default initial seed is used */
+
+		for (kk=0;kk<N-M;kk++) {
+			y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+			mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
+		}
+		for (;kk<N-1;kk++) {
+			y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+			mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
+		}
+		y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
+		mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
+
+		mti = 0;
+	}
+  
+	y = mt[mti++];
+
+	/* Tempering */
+	y ^= (y >> 11);
+	y ^= (y << 7) & 0x9d2c5680UL;
+	y ^= (y << 15) & 0xefc60000UL;
+	y ^= (y >> 18);
+
+	return y;
+}
+
+/* generates a random number on [0,0x7fffffff]-interval */
+long genrand_int31(void)
+{
+	return (long)(genrand_int32()>>1);
+}
+
+/* generates a random number on [0,1]-real-interval */
+double genrand_real1(void)
+{
+	return genrand_int32()*(1.0/4294967295.0); 
+	/* divided by 2^32-1 */ 
+}
+
+/* generates a random number on [0,1)-real-interval */
+double genrand_real2(void)
+{
+	return genrand_int32()*(1.0/4294967296.0); 
+	/* divided by 2^32 */
+}
+
+/* generates a random number on (0,1)-real-interval */
+double genrand_real3(void)
+{
+	return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0); 
+	/* divided by 2^32 */
+}
+
+/* generates a random number on [0,1) with 53-bit resolution*/
+double genrand_res53(void) 
+{ 
+	unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6; 
+	return(a*67108864.0+b)*(1.0/9007199254740992.0); 
+} 
+/* These real versions are due to Isaku Wada, 2002/01/09 added */
+
+//int main(void)
+//{
+//	int i;
+//	unsigned long init[4]={0x123, 0x234, 0x345, 0x456}, length=4;
+//	init_by_array(init, length);
+//	printf("1000 outputs of genrand_int32()\n");
+//	for (i=0; i<1000; i++) {
+//		printf("%10lu ", genrand_int32());
+//		if (i%5==4) printf("\n");
+//	}
+//	printf("\n1000 outputs of genrand_real2()\n");
+//	for (i=0; i<1000; i++) {
+//		printf("%10.8f ", genrand_real2());
+//		if (i%5==4) printf("\n");
+//	}
+//	return 0;
+//}

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 1/readme.txt

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+Corwin Perren - Concurrency HW 1
+
+To make this program on the os server, cd into this directory and run "make".
+
+To run the program, type "./concurrency1" into the terminal and hit enter.

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 2/main.c

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+/* 
+ * File:   main.c
+ * Author: caperren
+ *
+ * Created on April 27th, 2018
+ */
+
+#include "mt19937ar.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <sys/param.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <semaphore.h>
+
+// Program defines you might want to change
+#define NUM_PHILOSOPHERS 5
+
+#define MIN_RANDOM_EAT 2
+#define MAX_RANDOM_EAT 9
+
+#define MIN_RANDOM_THINK 1
+#define MAX_RANDOM_THINK 20
+
+uint8_t* philosopher_names[] = {
+    "Plato",
+    "Aristotle",
+    "Socrates",
+    "Confucius",
+    "Voltaire"    
+};
+
+//RDRAND value to check for
+#define RDRAND_FLAG (1 << 30)
+
+sem_t fork_semaphores[NUM_PHILOSOPHERS];
+uint32_t philosopher_eat_counts[NUM_PHILOSOPHERS];
+
+// Get random number based on whether rdrand is supported.
+uint8_t get_random_number(uint8_t min, uint8_t max) {
+    uint8_t rand_val;
+    unsigned long seed;
+
+    unsigned int eax;
+    unsigned int ebx;
+    unsigned int ecx;
+    unsigned int edx;
+
+    eax = 0x01;
+
+    // ASM for checking if RDRAND supported
+    __asm__ __volatile__("cpuid"
+            : "=a" (eax),
+            "=b" (ebx),
+            "=c" (ecx),
+            "=d" (edx)
+            : "a" (1),
+            "c" (0)
+            );
+
+    // Seed random with /dev/random
+    int random = open("/dev/random", O_RDONLY);
+    read(random, &seed, sizeof (seed));
+
+    unsigned int random_value;
+
+    if ((ecx & RDRAND_FLAG) == RDRAND_FLAG) {
+	char return_code = 0;
+	char count = 0;
+
+        // ASM for RDRAND
+	while(return_code != 1 && count < 10){
+		__asm__ volatile(
+		        "rdrand %0 ; setc %1"
+		        : "=r" (random_value), "=qm" (return_code)
+		);
+
+		count++;
+	}
+    } else {
+        // Twister if RDRAND not supported
+        init_genrand(seed);
+	random_value = genrand_int32();
+    }
+
+    return (random_value % (max + 1 - min)) + min;
+}
+
+void think(uint8_t *name){
+    uint8_t random = get_random_number(MIN_RANDOM_THINK, MAX_RANDOM_THINK);
+    
+    printf("%s thinking for %u seconds.\n", name, random);
+    fflush(stdout);
+    
+    sleep(random);
+}
+
+void eat(uint8_t *name){
+    uint8_t random = get_random_number(MIN_RANDOM_EAT, MAX_RANDOM_EAT);
+    
+    printf("%s eating for %u seconds.\n", name, random);
+    fflush(stdout);
+    
+    sleep(random);
+}
+
+void *philosopher(void *number){
+    // Store values that will be useful as the thread runs
+    uint16_t philosophers_number = *((uint16_t *) number);
+    uint16_t philosophers_number_plus_one = philosophers_number + 1;
+    uint16_t fork_num_plus_one = philosophers_number_plus_one % NUM_PHILOSOPHERS;
+    
+    while(1){
+        // Think
+        think(philosopher_names[philosophers_number]);
+        
+        // Get forks
+        printf("%s waiting for forks %u and %u.\n", philosopher_names[philosophers_number], philosophers_number, fork_num_plus_one);
+        fflush(stdout);
+        
+        sem_wait(&fork_semaphores[MIN(philosophers_number, fork_num_plus_one)]);
+        sem_wait(&fork_semaphores[MAX(philosophers_number, fork_num_plus_one)]);
+        
+        printf("%s now has forks %u and %u.\n", philosopher_names[philosophers_number], philosophers_number, fork_num_plus_one);
+        fflush(stdout);
+        
+        // Eat 
+        eat(philosopher_names[philosophers_number]);
+        philosopher_eat_counts[philosophers_number]++;
+        
+        // Release forks
+        printf("%s releasing forks %u and %u.\n", philosopher_names[philosophers_number], philosophers_number, fork_num_plus_one);
+        fflush(stdout);
+        
+        sem_post(&fork_semaphores[philosophers_number]);
+        sem_post(&fork_semaphores[fork_num_plus_one]);
+    
+    }
+    
+}
+
+int main(int argc, char **argv) {
+    // Containers to hold our threads, and the philosopher index
+    pthread_t consumer_threads[NUM_PHILOSOPHERS];
+    uint16_t philosophers_numbers[NUM_PHILOSOPHERS];
+    
+    // Initialize semaphores, and arrays used to keep track of things
+    for(uint16_t i = 0 ; i < NUM_PHILOSOPHERS ; i++){
+        sem_init(&fork_semaphores[i], 0, 1);
+        philosophers_numbers[i] = i;
+        philosopher_eat_counts[i] = 0;
+    }
+    
+    // Create all the philosopher threads
+    for(uint16_t i = 0 ; i < NUM_PHILOSOPHERS ; i++){
+        if(pthread_create(&consumer_threads[i], NULL, philosopher, &philosophers_numbers[i])) {
+            fprintf(stderr, "Error creating thread\n");
+            return 1;
+        }
+    }
+    
+    // This monitoring while loop prints our the eating counts of the 
+    // philosophers so you can easily see how often they've ate without 
+    // having to dig through the text output. It runs once every five seconds.
+    while(1){
+        sleep(5);
+        
+        printf("\n####################\nEat Counts\n");
+        
+        for(uint16_t i = 0 ; i < NUM_PHILOSOPHERS ; i++){
+            printf("%s: %u\n", philosopher_names[i], philosopher_eat_counts[i]);
+        }
+        
+        printf("####################\n\n");
+        
+        fflush(stdout);
+        
+    }
+    
+    return 0;
+}
+

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 2/makefile

@@ -0,0 +1,8 @@
+all: clean build
+	
+clean:
+	rm -f *.o
+	rm -f concurrency2
+	
+build:
+	gcc main.c mt19937ar.h -o concurrency2 -std=c99 -lpthread -lrt

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 2/mt19937ar.h

@@ -0,0 +1,190 @@
+/* 
+   A C-program for MT19937, with initialization improved 2002/1/26.
+   Coded by Takuji Nishimura and Makoto Matsumoto.
+
+   Before using, initialize the state by using init_genrand(seed)  
+   or init_by_array(init_key, key_length).
+
+   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
+   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. The names of its contributors may not 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 OWNER 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.
+
+
+   Any feedback is very welcome.
+   http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
+   email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
+*/
+
+#include <stdio.h>
+
+/* Period parameters */  
+#define N 624
+#define M 397
+#define MATRIX_A 0x9908b0dfUL   /* constant vector a */
+#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
+#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
+
+static unsigned long mt[N]; /* the array for the state vector  */
+static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
+
+/* initializes mt[N] with a seed */
+void init_genrand(unsigned long s)
+{
+	mt[0]= s & 0xffffffffUL;
+	for (mti=1; mti<N; mti++) {
+		mt[mti] = 
+			(1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti); 
+		/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
+		/* In the previous versions, MSBs of the seed affect   */
+		/* only MSBs of the array mt[].                        */
+		/* 2002/01/09 modified by Makoto Matsumoto             */
+		mt[mti] &= 0xffffffffUL;
+		/* for >32 bit machines */
+	}
+}
+
+/* initialize by an array with array-length */
+/* init_key is the array for initializing keys */
+/* key_length is its length */
+/* slight change for C++, 2004/2/26 */
+void init_by_array(unsigned long init_key[], int key_length)
+{
+	int i, j, k;
+	init_genrand(19650218UL);
+	i=1; j=0;
+	k = (N>key_length ? N : key_length);
+	for (; k; k--) {
+		mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
+			+ init_key[j] + j; /* non linear */
+		mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+		i++; j++;
+		if (i>=N) { mt[0] = mt[N-1]; i=1; }
+		if (j>=key_length) j=0;
+	}
+	for (k=N-1; k; k--) {
+		mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
+			- i; /* non linear */
+		mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+		i++;
+		if (i>=N) { mt[0] = mt[N-1]; i=1; }
+	}
+
+	mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */ 
+}
+
+/* generates a random number on [0,0xffffffff]-interval */
+unsigned long genrand_int32(void)
+{
+	unsigned long y;
+	static unsigned long mag01[2]={0x0UL, MATRIX_A};
+	/* mag01[x] = x * MATRIX_A  for x=0,1 */
+
+	if (mti >= N) { /* generate N words at one time */
+		int kk;
+
+		if (mti == N+1)   /* if init_genrand() has not been called, */
+			init_genrand(5489UL); /* a default initial seed is used */
+
+		for (kk=0;kk<N-M;kk++) {
+			y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+			mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
+		}
+		for (;kk<N-1;kk++) {
+			y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+			mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
+		}
+		y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
+		mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
+
+		mti = 0;
+	}
+  
+	y = mt[mti++];
+
+	/* Tempering */
+	y ^= (y >> 11);
+	y ^= (y << 7) & 0x9d2c5680UL;
+	y ^= (y << 15) & 0xefc60000UL;
+	y ^= (y >> 18);
+
+	return y;
+}
+
+/* generates a random number on [0,0x7fffffff]-interval */
+long genrand_int31(void)
+{
+	return (long)(genrand_int32()>>1);
+}
+
+/* generates a random number on [0,1]-real-interval */
+double genrand_real1(void)
+{
+	return genrand_int32()*(1.0/4294967295.0); 
+	/* divided by 2^32-1 */ 
+}
+
+/* generates a random number on [0,1)-real-interval */
+double genrand_real2(void)
+{
+	return genrand_int32()*(1.0/4294967296.0); 
+	/* divided by 2^32 */
+}
+
+/* generates a random number on (0,1)-real-interval */
+double genrand_real3(void)
+{
+	return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0); 
+	/* divided by 2^32 */
+}
+
+/* generates a random number on [0,1) with 53-bit resolution*/
+double genrand_res53(void) 
+{ 
+	unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6; 
+	return(a*67108864.0+b)*(1.0/9007199254740992.0); 
+} 
+/* These real versions are due to Isaku Wada, 2002/01/09 added */
+
+//int main(void)
+//{
+//	int i;
+//	unsigned long init[4]={0x123, 0x234, 0x345, 0x456}, length=4;
+//	init_by_array(init, length);
+//	printf("1000 outputs of genrand_int32()\n");
+//	for (i=0; i<1000; i++) {
+//		printf("%10lu ", genrand_int32());
+//		if (i%5==4) printf("\n");
+//	}
+//	printf("\n1000 outputs of genrand_real2()\n");
+//	for (i=0; i<1000; i++) {
+//		printf("%10.8f ", genrand_real2());
+//		if (i%5==4) printf("\n");
+//	}
+//	return 0;
+//}

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 2/readme.txt

@@ -0,0 +1,5 @@
+Corwin Perren - Concurrency HW 2
+
+To make this program on the os server, cd into this directory and run "make".
+
+To run the program, type "./concurrency2" into the terminal and hit enter.

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 3/makefile

@@ -0,0 +1,9 @@
+all: clean build
+	
+clean:
+	rm -f *.o
+	rm -f concurrency3_problem1 concurrency3_problem2
+	
+build:
+	gcc problem1.c mt19937ar.h -o concurrency3_problem1 -std=c99 -lpthread -lrt
+	gcc problem2.c mt19937ar.h -o concurrency3_problem2 -std=c99 -lpthread -lrt

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 3/mt19937ar.h

@@ -0,0 +1,190 @@
+/* 
+   A C-program for MT19937, with initialization improved 2002/1/26.
+   Coded by Takuji Nishimura and Makoto Matsumoto.
+
+   Before using, initialize the state by using init_genrand(seed)  
+   or init_by_array(init_key, key_length).
+
+   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
+   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. The names of its contributors may not 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 OWNER 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.
+
+
+   Any feedback is very welcome.
+   http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
+   email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
+*/
+
+#include <stdio.h>
+
+/* Period parameters */  
+#define N 624
+#define M 397
+#define MATRIX_A 0x9908b0dfUL   /* constant vector a */
+#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
+#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
+
+static unsigned long mt[N]; /* the array for the state vector  */
+static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
+
+/* initializes mt[N] with a seed */
+void init_genrand(unsigned long s)
+{
+	mt[0]= s & 0xffffffffUL;
+	for (mti=1; mti<N; mti++) {
+		mt[mti] = 
+			(1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti); 
+		/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
+		/* In the previous versions, MSBs of the seed affect   */
+		/* only MSBs of the array mt[].                        */
+		/* 2002/01/09 modified by Makoto Matsumoto             */
+		mt[mti] &= 0xffffffffUL;
+		/* for >32 bit machines */
+	}
+}
+
+/* initialize by an array with array-length */
+/* init_key is the array for initializing keys */
+/* key_length is its length */
+/* slight change for C++, 2004/2/26 */
+void init_by_array(unsigned long init_key[], int key_length)
+{
+	int i, j, k;
+	init_genrand(19650218UL);
+	i=1; j=0;
+	k = (N>key_length ? N : key_length);
+	for (; k; k--) {
+		mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
+			+ init_key[j] + j; /* non linear */
+		mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+		i++; j++;
+		if (i>=N) { mt[0] = mt[N-1]; i=1; }
+		if (j>=key_length) j=0;
+	}
+	for (k=N-1; k; k--) {
+		mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
+			- i; /* non linear */
+		mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+		i++;
+		if (i>=N) { mt[0] = mt[N-1]; i=1; }
+	}
+
+	mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */ 
+}
+
+/* generates a random number on [0,0xffffffff]-interval */
+unsigned long genrand_int32(void)
+{
+	unsigned long y;
+	static unsigned long mag01[2]={0x0UL, MATRIX_A};
+	/* mag01[x] = x * MATRIX_A  for x=0,1 */
+
+	if (mti >= N) { /* generate N words at one time */
+		int kk;
+
+		if (mti == N+1)   /* if init_genrand() has not been called, */
+			init_genrand(5489UL); /* a default initial seed is used */
+
+		for (kk=0;kk<N-M;kk++) {
+			y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+			mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
+		}
+		for (;kk<N-1;kk++) {
+			y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+			mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
+		}
+		y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
+		mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
+
+		mti = 0;
+	}
+  
+	y = mt[mti++];
+
+	/* Tempering */
+	y ^= (y >> 11);
+	y ^= (y << 7) & 0x9d2c5680UL;
+	y ^= (y << 15) & 0xefc60000UL;
+	y ^= (y >> 18);
+
+	return y;
+}
+
+/* generates a random number on [0,0x7fffffff]-interval */
+long genrand_int31(void)
+{
+	return (long)(genrand_int32()>>1);
+}
+
+/* generates a random number on [0,1]-real-interval */
+double genrand_real1(void)
+{
+	return genrand_int32()*(1.0/4294967295.0); 
+	/* divided by 2^32-1 */ 
+}
+
+/* generates a random number on [0,1)-real-interval */
+double genrand_real2(void)
+{
+	return genrand_int32()*(1.0/4294967296.0); 
+	/* divided by 2^32 */
+}
+
+/* generates a random number on (0,1)-real-interval */
+double genrand_real3(void)
+{
+	return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0); 
+	/* divided by 2^32 */
+}
+
+/* generates a random number on [0,1) with 53-bit resolution*/
+double genrand_res53(void) 
+{ 
+	unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6; 
+	return(a*67108864.0+b)*(1.0/9007199254740992.0); 
+} 
+/* These real versions are due to Isaku Wada, 2002/01/09 added */
+
+//int main(void)
+//{
+//	int i;
+//	unsigned long init[4]={0x123, 0x234, 0x345, 0x456}, length=4;
+//	init_by_array(init, length);
+//	printf("1000 outputs of genrand_int32()\n");
+//	for (i=0; i<1000; i++) {
+//		printf("%10lu ", genrand_int32());
+//		if (i%5==4) printf("\n");
+//	}
+//	printf("\n1000 outputs of genrand_real2()\n");
+//	for (i=0; i<1000; i++) {
+//		printf("%10.8f ", genrand_real2());
+//		if (i%5==4) printf("\n");
+//	}
+//	return 0;
+//}

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 3/problem1.c

@@ -0,0 +1,172 @@
+/* 
+ * File:   main.c
+ * Author: caperren
+ *
+ * Created on April 27th, 2018
+ */
+
+#include "mt19937ar.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <sys/param.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <semaphore.h>
+
+// Program defines you might want to change
+#define MAX_NUM_THREADS 4
+#define MAX_RESOURCE_USAGE 3
+
+#define MIN_RANDOM_USE_WAIT 3
+#define MAX_RANDOM_USE_WAIT 5
+
+//RDRAND value to check for
+#define RDRAND_FLAG (1 << 30)
+
+sem_t resource_semaphore;
+uint8_t wait_for_resource_recovery = 0;
+
+// Get random number based on whether rdrand is supported.
+uint8_t get_random_number(uint8_t min, uint8_t max) {
+    uint8_t rand_val;
+    unsigned long seed;
+
+    unsigned int eax;
+    unsigned int ebx;
+    unsigned int ecx;
+    unsigned int edx;
+
+    eax = 0x01;
+
+    // ASM for checking if RDRAND supported
+    __asm__ __volatile__("cpuid"
+            : "=a" (eax),
+            "=b" (ebx),
+            "=c" (ecx),
+            "=d" (edx)
+            : "a" (1),
+            "c" (0)
+            );
+
+    // Seed random with /dev/random
+    int random = open("/dev/random", O_RDONLY);
+    read(random, &seed, sizeof (seed));
+
+    unsigned int random_value;
+
+    if ((ecx & RDRAND_FLAG) == RDRAND_FLAG) {
+	char return_code = 0;
+	char count = 0;
+
+        // ASM for RDRAND
+	while(return_code != 1 && count < 10){
+		__asm__ volatile(
+		        "rdrand %0 ; setc %1"
+		        : "=r" (random_value), "=qm" (return_code)
+		);
+
+		count++;
+	}
+    } else {
+        // Twister if RDRAND not supported
+        init_genrand(seed);
+	random_value = genrand_int32();
+    }
+
+    return (random_value % (max + 1 - min)) + min;
+}
+
+
+void resource_user_wait(uint8_t id, uint8_t *wait_kind){
+    uint8_t random = get_random_number(MIN_RANDOM_USE_WAIT, MAX_RANDOM_USE_WAIT);
+    
+    printf("Resource user %d waiting %u seconds for %s.\n", id, random, wait_kind);
+    fflush(stdout);
+    
+    sleep(random);
+}
+
+void *resource_user(void *thread_num){
+    
+    uint8_t thread_number = *((uint8_t *)thread_num);
+    
+    printf("Resourcing using thread with id: %d now running.\n", thread_number);
+    fflush(stdout);
+  
+    while(1){
+        resource_user_wait(thread_number, "initial wait");
+        
+        if(wait_for_resource_recovery){
+            printf("Resource user %d waiting for recovery of all resources.\n", thread_number);
+            fflush(stdout);
+            while(wait_for_resource_recovery);
+        }
+        
+        sem_wait(&resource_semaphore);
+        
+        printf("Resource user %d now using resource.\n", thread_number);
+        fflush(stdout);
+        
+        resource_user_wait(thread_number, "usage wait");
+        
+        printf("Resource user %d done with resource.\n", thread_number);
+        fflush(stdout);
+        
+        sem_post(&resource_semaphore);
+    }
+}
+
+int main(int argc, char **argv) {
+    // Containers to hold our threads, and the philosopher index
+    pthread_t usage_threads[MAX_NUM_THREADS];
+    uint8_t thread_id_numbers[MAX_NUM_THREADS];
+    
+    // Initialize semaphores, and arrays used to keep track of things
+    sem_init(&resource_semaphore, 0, MAX_RESOURCE_USAGE);
+    
+    for(uint8_t i = 0 ; i < MAX_NUM_THREADS ; i++){
+        thread_id_numbers[i] = i;
+    }
+    
+    // Create all the philosopher threads
+    for(uint8_t i = 0 ; i < MAX_NUM_THREADS ; i++){
+        if(pthread_create(&usage_threads[i], NULL, resource_user, &thread_id_numbers[i])) {
+            fprintf(stderr, "Error creating thread\n");
+            return 1;
+        }
+    }
+    
+    int used_semaphores = 0;
+    uint8_t resources_left = MAX_RESOURCE_USAGE;
+    uint8_t last_resources_left_value = resources_left;
+    
+    
+    while(1){
+        sem_getvalue(&resource_semaphore, &used_semaphores);
+        
+        resources_left = MAX_RESOURCE_USAGE - used_semaphores;
+        
+        if(resources_left != last_resources_left_value){
+                    
+            printf("Manager ### Resources currently used: %d\n", resources_left);
+            fflush(stdout);
+            
+            if(resources_left == MAX_RESOURCE_USAGE){
+                printf("Manager ### Maximum resources used. Locking out.\n");
+                fflush(stdout);
+                wait_for_resource_recovery = 1;
+            }else if (resources_left == 0){
+                wait_for_resource_recovery = 0;
+            }
+            
+            last_resources_left_value = resources_left;
+        }  
+    }
+    
+    return 0;
+}
+

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 3/problem2.c

@@ -0,0 +1,339 @@
+/* 
+ * File:   main.c
+ * Author: caperren
+ *
+ * Created on April 27th, 2018
+ */
+
+#include "mt19937ar.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <sys/param.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <semaphore.h>
+
+////////// Program defines you might want to change //////////
+#define NUM_INSERTERS 2
+#define NUM_DELETERS 2
+#define NUM_SEARCHERS 2
+
+#define MIN_NUMBER 0
+#define MAX_NUMBER 10
+
+#define MIN_SLEEP_INSERTER 2
+#define MAX_SLEEP_INSERTER 4
+
+#define MIN_SLEEP_SEARCHER 1
+#define MAX_SLEEP_SEARCHER 2
+
+#define MIN_SLEEP_DELETER 10
+#define MAX_SLEEP_DELETER 15
+
+////////// Global variables and structs for linked list //////////
+typedef struct linked_list {
+    struct linked_list *next;
+    uint16_t value;
+} linked_list;
+
+linked_list *list_head = NULL;
+uint16_t list_size = 0;
+
+
+////////// Global variables and structs for threading and sempaphores //////////
+typedef struct light_switch {
+    uint16_t counter;
+    sem_t mutex;
+} light_switch;
+
+
+sem_t no_searches_semaphore;
+sem_t no_insertions_semaphore;
+sem_t insertion_mutex;
+
+light_switch insertion_light_switch;
+light_switch search_light_switch;
+
+
+////////// Other global variables //////////
+//RDRAND value to check for
+#define RDRAND_FLAG (1 << 30)
+
+// Get random number based on whether rdrand is supported.
+uint8_t get_random_number(uint8_t min, uint8_t max) {
+    uint8_t rand_val;
+    unsigned long seed;
+
+    unsigned int eax;
+    unsigned int ebx;
+    unsigned int ecx;
+    unsigned int edx;
+
+    eax = 0x01;
+
+    // ASM for checking if RDRAND supported
+    __asm__ __volatile__("cpuid"
+            : "=a" (eax),
+            "=b" (ebx),
+            "=c" (ecx),
+            "=d" (edx)
+            : "a" (1),
+            "c" (0)
+            );
+
+    // Seed random with /dev/random
+    int random = open("/dev/random", O_RDONLY);
+    read(random, &seed, sizeof (seed));
+
+    unsigned int random_value;
+
+    if ((ecx & RDRAND_FLAG) == RDRAND_FLAG) {
+	char return_code = 0;
+	char count = 0;
+
+        // ASM for RDRAND
+	while(return_code != 1 && count < 10){
+		__asm__ volatile(
+		        "rdrand %0 ; setc %1"
+		        : "=r" (random_value), "=qm" (return_code)
+		);
+
+		count++;
+	}
+    } else {
+        // Twister if RDRAND not supported
+        init_genrand(seed);
+	    random_value = genrand_int32();
+    }
+
+    return (random_value % (max + 1 - min)) + min;
+}
+
+void insert_linked_list(uint16_t value){
+    linked_list *new = malloc(sizeof(linked_list));
+    new->next = NULL;
+    new->value = value;
+
+    if(list_head == NULL){
+        list_head = new;
+    }else{
+        linked_list *cursor = list_head;
+
+        while(cursor->next != NULL){
+            cursor = cursor->next;
+        }
+        cursor->next = new;
+    }
+
+    list_size++;
+}
+
+void delete_position_from_linked_list(uint16_t position) {
+    linked_list *cursor_prev = list_head;
+    linked_list *cursor_current = list_head;
+
+    if(list_head == NULL || position >= list_size){
+        return;
+    }
+
+    if(position == 0){
+        list_head = cursor_current->next;
+        free(cursor_current);
+    }else{
+        for(uint16_t i = 0 ; i < position ; i++){
+            cursor_prev = cursor_current;
+            cursor_current = cursor_current->next;
+        }
+
+        cursor_prev->next = cursor_current->next;
+        free(cursor_current);
+    }
+
+    list_size--;
+}
+
+int16_t position_of_value_linked_list(uint16_t value){
+    linked_list *cursor_current = list_head;
+
+    if(list_head == NULL){
+        return -1;
+    }
+
+    uint16_t count = 0;
+
+    do{
+        if(cursor_current->value == value){
+            return count;
+        }
+
+        count++;
+        cursor_current = cursor_current->next;
+    }while(cursor_current != NULL);
+
+    return -1;
+}
+
+void light_switch_lock(light_switch *current_light_switch, sem_t *current_semaphore){
+    sem_wait(&current_light_switch->mutex);
+    current_light_switch->counter++;
+
+    if(current_light_switch->counter == 1){
+        sem_wait(current_semaphore);
+    }
+
+    sem_post(&current_light_switch->mutex);
+}
+
+void light_switch_unlock(light_switch *current_light_switch, sem_t *current_semaphore){
+    sem_wait(&current_light_switch->mutex);
+    current_light_switch->counter--;
+
+    if(current_light_switch->counter == 0){
+        sem_post(current_semaphore);
+    }
+
+    sem_post(&current_light_switch->mutex);
+}
+
+void *inserter_thread(){
+    printf("Inserter starting.\n");
+    fflush(stdout);
+
+    sleep(2); //Do this so you can easily see threads starting
+
+    while(1){
+        uint16_t new_number = get_random_number(MIN_NUMBER, MAX_NUMBER);
+        uint16_t sleep_time = get_random_number(MIN_SLEEP_INSERTER, MAX_SLEEP_INSERTER);
+
+        printf("Inserter going to sleep for %d seconds.\n", sleep_time);
+        fflush(stdout);
+        sleep(sleep_time);
+
+        printf("Inserter awake and waiting for access.\n");
+        fflush(stdout);
+        light_switch_lock(&insertion_light_switch, &no_insertions_semaphore);
+        sem_wait(&insertion_mutex);
+
+        printf("Inserter now has access.\n");
+        printf("Inserting number %u.\n", new_number);
+        fflush(stdout);
+        insert_linked_list(new_number);
+
+        sem_post(&insertion_mutex);
+        light_switch_unlock(&insertion_light_switch, &no_insertions_semaphore);
+    }
+}
+
+void *searcher_thread(){
+    printf("Searcher starting.\n");
+    fflush(stdout);
+
+    sleep(2); //Do this so you can easily see threads starting
+
+    while(1){
+        uint16_t search_value = get_random_number(MIN_NUMBER, MAX_NUMBER);
+        uint16_t sleep_time = get_random_number(MIN_SLEEP_SEARCHER, MAX_SLEEP_SEARCHER);
+
+        printf("Searcher going to sleep for %d seconds.\n", sleep_time);
+        fflush(stdout);
+        sleep(sleep_time);
+
+        printf("Searcher awake and waiting for access.\n");
+        fflush(stdout);
+        light_switch_lock(&search_light_switch, &no_searches_semaphore);
+
+        printf("Searcher has access.\n");
+        fflush(stdout);
+
+        int16_t value = position_of_value_linked_list(search_value);
+
+        if(value != -1){
+            printf("Search successful. Found value %d.\n", value);
+        } else {
+            printf("Search unsuccessful. Could not find value %u.\n", search_value);
+        }
+        fflush(stdout);
+
+        light_switch_unlock(&search_light_switch, &no_searches_semaphore);
+
+    }
+}
+
+void *deleter_thread(){
+    printf("Deleter starting.\n");
+    fflush(stdout);
+
+    sleep(2); //Do this so you can easily see threads starting
+
+    while(1){
+        uint16_t sleep_time = get_random_number(MIN_SLEEP_DELETER, MAX_SLEEP_DELETER);
+
+        printf("Deleter going to sleep for %d seconds.\n", sleep_time);
+        fflush(stdout);
+        sleep(sleep_time);
+
+        printf("Deleter awake and waiting for access.\n");
+        fflush(stdout);
+        sem_wait(&no_searches_semaphore);
+        sem_wait(&no_insertions_semaphore);
+
+        uint16_t delete_position = get_random_number(0, list_size);
+
+        printf("Deleter has access.\n");
+        printf("Deleting node at position %d.\n", delete_position);
+        fflush(stdout);
+        delete_position_from_linked_list(delete_position);
+
+        sem_post(&no_insertions_semaphore);
+        sem_post(&no_searches_semaphore);
+    }
+}
+
+int main(int argc, char **argv) {
+    // Storage for threads
+    pthread_t inserters[NUM_INSERTERS];
+    pthread_t searchers[NUM_INSERTERS];
+    pthread_t deleters[NUM_INSERTERS];
+
+    // Initialize light switches
+    sem_init(&insertion_light_switch.mutex, 1, 1);
+    insertion_light_switch.counter = 0;
+
+    sem_init(&search_light_switch.mutex, 1, 1);
+    search_light_switch.counter = 0;
+
+    // Initialize other semaphores and mutex
+    sem_init(&no_insertions_semaphore, 1, 1);
+    sem_init(&no_searches_semaphore, 1, 1);
+    sem_init(&insertion_mutex, 1, 1);
+
+    // Spin up threads
+    for(uint8_t i = 0 ; i < NUM_INSERTERS ; i++){
+        pthread_create(&inserters[i], NULL, inserter_thread, NULL);
+    }
+
+    for(uint8_t i = 0 ; i < NUM_SEARCHERS ; i++){
+        pthread_create(&searchers[i], NULL, searcher_thread, NULL);
+    }
+
+    for(uint8_t i = 0 ; i < NUM_DELETERS ; i++){
+        pthread_create(&deleters[i], NULL, deleter_thread, NULL);
+    }
+
+    // Wait for threads to join for completion.
+    for(uint8_t i = 0 ; i < NUM_INSERTERS ; i++){
+        pthread_join(inserters[i], NULL);
+    }
+
+    for(uint8_t i = 0 ; i < NUM_SEARCHERS ; i++){
+        pthread_join(searchers[i], NULL);
+    }
+
+    for(uint8_t i = 0 ; i < NUM_DELETERS ; i++){
+        pthread_join(deleters[i], NULL);
+    }
+}

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 3/readme.txt

@@ -0,0 +1,6 @@
+Corwin Perren - Concurrency HW 3
+
+To make this program on the os server, cd into this directory and run "make".
+
+To run program1, type "./concurrency3_problem1" into the terminal and hit enter.
+To run program2, type "./concurrency3_problem2" into the terminal and hit enter.

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 4/main.c

@@ -0,0 +1,262 @@
+/* 
+ * File:   main.c
+ * Author: caperren
+ *
+ * Created on June 1st, 2018
+ */
+#define _POSIX_C_SOURCE 199309L
+
+#include "mt19937ar.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <sys/param.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <time.h>
+
+// Program defines you might want to change
+#define NUM_BARBERSHOP_WAITING_ROOM_CHAIRS 5
+
+// Program defines that don't get changed
+#define NUM_CUSTOMER_THREADS (NUM_BARBERSHOP_WAITING_ROOM_CHAIRS * 2)
+
+#define MIN_RANDOM_WAIT_CUSTOMER_RESPAWN 4
+#define MAX_RANDOM_WAIT_CUSTOMER_RESPAWN 8
+
+#define MIN_RANDOM_HAIRCUT_TIME 2
+#define MAX_RANDOM_HAIRCUT_TIME 4
+
+//RDRAND value to check for
+#define RDRAND_FLAG (1 << 30)
+
+// Global Variables 
+sem_t waiting_room_chairs_semaphore;
+sem_t ticket_dispenser_semaphore;
+sem_t barber_chair_semaphore;
+
+uint16_t current_ticket_number = 1;
+uint16_t barber_servicing_ticket = 0;
+
+uint8_t haircut_started = 0;
+uint8_t haircut_over = 0;
+
+struct timespec thread_sleep_time;
+
+///////////////////////////////////////////////////////////////////
+// Get random number based on whether rdrand is supported.
+uint8_t get_random_number(uint8_t min, uint8_t max) {
+    uint8_t rand_val;
+    unsigned long seed;
+
+    unsigned int eax;
+    unsigned int ebx;
+    unsigned int ecx;
+    unsigned int edx;
+
+    eax = 0x01;
+
+    // ASM for checking if RDRAND supported
+    __asm__ __volatile__("cpuid"
+            : "=a" (eax),
+            "=b" (ebx),
+            "=c" (ecx),
+            "=d" (edx)
+            : "a" (1),
+            "c" (0)
+            );
+
+    // Seed random with /dev/random
+    int random = open("/dev/random", O_RDONLY);
+    read(random, &seed, sizeof (seed));
+
+    unsigned int random_value;
+
+    if ((ecx & RDRAND_FLAG) == RDRAND_FLAG) {
+	char return_code = 0;
+	char count = 0;
+
+        // ASM for RDRAND
+	while(return_code != 1 && count < 10){
+		__asm__ volatile(
+		        "rdrand %0 ; setc %1"
+		        : "=r" (random_value), "=qm" (return_code)
+		);
+
+		count++;
+	}
+    } else {
+        // Twister if RDRAND not supported
+        init_genrand(seed);
+	random_value = genrand_int32();
+    }
+
+    return (random_value % (max + 1 - min)) + min;
+}
+
+void get_hair_cut(uint16_t customer_thread_id, uint16_t ticket_id){
+   
+    while(!haircut_started){
+        nanosleep(&thread_sleep_time, NULL);
+    }
+    
+    printf("Customer heading to barbers chair with ticket number %u.\n", ticket_id);
+    fflush(stdout);
+    
+    sem_wait(&barber_chair_semaphore);
+    
+    printf("Customer with thread id %u and ticket number %u sat down and getting haircut.\n", customer_thread_id, ticket_id);
+    fflush(stdout);
+    
+    while(!haircut_over){
+        nanosleep(&thread_sleep_time, NULL);
+    }
+    
+    sem_post(&barber_chair_semaphore);
+    
+}
+
+void cut_hair(){
+    uint16_t sleep_time = get_random_number(MIN_RANDOM_HAIRCUT_TIME, MAX_RANDOM_HAIRCUT_TIME);
+    int customer_in_chair = 1;
+    
+    haircut_over = 0;
+    haircut_started = 1;
+    
+    printf("Barber waiting for customer to sit down with ticket number %d.\n", barber_servicing_ticket);
+    fflush(stdout);
+    while(customer_in_chair > 0){
+        sem_getvalue(&barber_chair_semaphore, &customer_in_chair);
+        nanosleep(&thread_sleep_time, NULL);
+    
+    }
+    
+    printf("Barber giving haircut to ticket number %d for %d seconds.\n", barber_servicing_ticket, sleep_time);
+    fflush(stdout);
+    
+    sleep(sleep_time);
+    
+    haircut_started = 0;
+    haircut_over = 1;
+    
+    while(customer_in_chair <= 0){
+        sem_getvalue(&barber_chair_semaphore, &customer_in_chair);
+        nanosleep(&thread_sleep_time, NULL);
+    }
+    
+    printf("Barber finished haircut for ticket number %d.\n", barber_servicing_ticket);
+    fflush(stdout);
+}
+
+// If waiting room is empty, sleep until woken up by customer
+// If customer, cut_hair
+void *barber(){
+    printf("Barber thread started.\n");
+    fflush(stdout);
+    
+    int used_waiting_room_chairs = 0;
+    
+    while(1){
+        // Check if anyone is in the waiting room
+        sem_getvalue(&waiting_room_chairs_semaphore, &used_waiting_room_chairs);
+        
+        if(used_waiting_room_chairs == 5){
+            nanosleep(&thread_sleep_time, NULL);
+            continue;
+        }
+        
+        // Tell customers next ticket number
+        barber_servicing_ticket++;
+        
+        // Service the customer
+        cut_hair();
+    }
+}
+
+// If the waiting room is full, customer leaves
+// If waiting room has empty chair, sits in chair, unless barber is ready
+// When ready, sits in chair and runs get_hair_cut, then leaves
+void *customer(void *thread_id_number){
+    uint16_t thread_id = *((uint16_t *)thread_id_number);
+
+    printf("Customer thread with id %d started.\n", thread_id);
+    fflush(stdout);
+    
+    int used_waiting_room_chairs = 0;
+    uint16_t customer_ticket_number = 0;
+    
+    while(1){
+        // Wait before deciding to enter store
+        uint16_t sleep_time = get_random_number(MIN_RANDOM_WAIT_CUSTOMER_RESPAWN, MAX_RANDOM_WAIT_CUSTOMER_RESPAWN);        
+        sleep(sleep_time);
+        
+        // Check if seats are full, exit store if full
+        sem_getvalue(&waiting_room_chairs_semaphore, &used_waiting_room_chairs);
+       
+        if(used_waiting_room_chairs == 0){
+            printf("Customer thread with id %d entered store, but was full. Leaving.\n", thread_id);
+            fflush(stdout);
+            continue;
+        }
+        
+        // There's space in the waiting room, take a seat and a number
+        sem_wait(&waiting_room_chairs_semaphore);
+        sem_wait(&ticket_dispenser_semaphore);
+        customer_ticket_number = current_ticket_number;
+        current_ticket_number++;
+        sem_post(&ticket_dispenser_semaphore);
+        
+        printf("Customer thread with id %d has ticket number %u.\n", thread_id, current_ticket_number);
+        fflush(stdout);
+        
+        // Wait until our number is called
+        while(barber_servicing_ticket != customer_ticket_number){
+            nanosleep(&thread_sleep_time, NULL);
+        }
+        
+        // It's time for a haircut, give up our seat in the waiting room
+        sem_post(&waiting_room_chairs_semaphore);
+        
+        // Get a haircut
+        get_hair_cut(thread_id, customer_ticket_number);        
+    }
+}
+
+int main(int argc, char **argv) {
+    // Setup thread sleep variable
+    thread_sleep_time.tv_nsec = 10000000;
+    thread_sleep_time.tv_sec = 0;
+    
+    // Storage for threads
+    pthread_t barber_thread;
+    pthread_t potential_customers_threads[NUM_CUSTOMER_THREADS];
+    uint16_t customers_thread_ids[NUM_CUSTOMER_THREADS];
+    
+    
+    // Initialize semaphores
+    sem_init(&waiting_room_chairs_semaphore, 1, NUM_BARBERSHOP_WAITING_ROOM_CHAIRS);
+    sem_init(&ticket_dispenser_semaphore, 1, 1);
+    sem_init(&barber_chair_semaphore, 1, 1);
+            
+    // Start barber thread
+    pthread_create(&barber_thread, NULL, barber, NULL);
+    
+    // Start potential custom threads
+    for(uint16_t i = 0 ; i < NUM_CUSTOMER_THREADS ; i++){
+        customers_thread_ids[i] = i;
+        pthread_create(&potential_customers_threads[i], NULL, customer, &customers_thread_ids[i]);
+    }
+    
+    // Wait for barber thread to finish
+    pthread_join(barber_thread, NULL);
+    
+    // Wait for customer threads to finish
+    for(uint8_t i = 0 ; i < NUM_CUSTOMER_THREADS ; i++){
+        pthread_join(potential_customers_threads[i], NULL);
+    }
+}
+

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 4/makefile

@@ -0,0 +1,8 @@
+all: clean build
+	
+clean:
+	rm -f *.o
+	rm -f concurrency4
+	
+build:
+	gcc main.c mt19937ar.h -o concurrency4 -std=c99 -lpthread -lrt

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 4/mt19937ar.h

@@ -0,0 +1,190 @@
+/* 
+   A C-program for MT19937, with initialization improved 2002/1/26.
+   Coded by Takuji Nishimura and Makoto Matsumoto.
+
+   Before using, initialize the state by using init_genrand(seed)  
+   or init_by_array(init_key, key_length).
+
+   Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
+   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. The names of its contributors may not 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 OWNER 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.
+
+
+   Any feedback is very welcome.
+   http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
+   email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
+*/
+
+#include <stdio.h>
+
+/* Period parameters */  
+#define N 624
+#define M 397
+#define MATRIX_A 0x9908b0dfUL   /* constant vector a */
+#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
+#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
+
+static unsigned long mt[N]; /* the array for the state vector  */
+static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
+
+/* initializes mt[N] with a seed */
+void init_genrand(unsigned long s)
+{
+	mt[0]= s & 0xffffffffUL;
+	for (mti=1; mti<N; mti++) {
+		mt[mti] = 
+			(1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti); 
+		/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
+		/* In the previous versions, MSBs of the seed affect   */
+		/* only MSBs of the array mt[].                        */
+		/* 2002/01/09 modified by Makoto Matsumoto             */
+		mt[mti] &= 0xffffffffUL;
+		/* for >32 bit machines */
+	}
+}
+
+/* initialize by an array with array-length */
+/* init_key is the array for initializing keys */
+/* key_length is its length */
+/* slight change for C++, 2004/2/26 */
+void init_by_array(unsigned long init_key[], int key_length)
+{
+	int i, j, k;
+	init_genrand(19650218UL);
+	i=1; j=0;
+	k = (N>key_length ? N : key_length);
+	for (; k; k--) {
+		mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
+			+ init_key[j] + j; /* non linear */
+		mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+		i++; j++;
+		if (i>=N) { mt[0] = mt[N-1]; i=1; }
+		if (j>=key_length) j=0;
+	}
+	for (k=N-1; k; k--) {
+		mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
+			- i; /* non linear */
+		mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+		i++;
+		if (i>=N) { mt[0] = mt[N-1]; i=1; }
+	}
+
+	mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */ 
+}
+
+/* generates a random number on [0,0xffffffff]-interval */
+unsigned long genrand_int32(void)
+{
+	unsigned long y;
+	static unsigned long mag01[2]={0x0UL, MATRIX_A};
+	/* mag01[x] = x * MATRIX_A  for x=0,1 */
+
+	if (mti >= N) { /* generate N words at one time */
+		int kk;
+
+		if (mti == N+1)   /* if init_genrand() has not been called, */
+			init_genrand(5489UL); /* a default initial seed is used */
+
+		for (kk=0;kk<N-M;kk++) {
+			y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+			mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
+		}
+		for (;kk<N-1;kk++) {
+			y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
+			mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
+		}
+		y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
+		mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
+
+		mti = 0;
+	}
+  
+	y = mt[mti++];
+
+	/* Tempering */
+	y ^= (y >> 11);
+	y ^= (y << 7) & 0x9d2c5680UL;
+	y ^= (y << 15) & 0xefc60000UL;
+	y ^= (y >> 18);
+
+	return y;
+}
+
+/* generates a random number on [0,0x7fffffff]-interval */
+long genrand_int31(void)
+{
+	return (long)(genrand_int32()>>1);
+}
+
+/* generates a random number on [0,1]-real-interval */
+double genrand_real1(void)
+{
+	return genrand_int32()*(1.0/4294967295.0); 
+	/* divided by 2^32-1 */ 
+}
+
+/* generates a random number on [0,1)-real-interval */
+double genrand_real2(void)
+{
+	return genrand_int32()*(1.0/4294967296.0); 
+	/* divided by 2^32 */
+}
+
+/* generates a random number on (0,1)-real-interval */
+double genrand_real3(void)
+{
+	return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0); 
+	/* divided by 2^32 */
+}
+
+/* generates a random number on [0,1) with 53-bit resolution*/
+double genrand_res53(void) 
+{ 
+	unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6; 
+	return(a*67108864.0+b)*(1.0/9007199254740992.0); 
+} 
+/* These real versions are due to Isaku Wada, 2002/01/09 added */
+
+//int main(void)
+//{
+//	int i;
+//	unsigned long init[4]={0x123, 0x234, 0x345, 0x456}, length=4;
+//	init_by_array(init, length);
+//	printf("1000 outputs of genrand_int32()\n");
+//	for (i=0; i<1000; i++) {
+//		printf("%10lu ", genrand_int32());
+//		if (i%5==4) printf("\n");
+//	}
+//	printf("\n1000 outputs of genrand_real2()\n");
+//	for (i=0; i<1000; i++) {
+//		printf("%10.8f ", genrand_real2());
+//		if (i%5==4) printf("\n");
+//	}
+//	return 0;
+//}

OSU Coursework/CS 444 - Operating Systems II/Concurrency Assignments/Concurrency 4/readme.txt

@@ -0,0 +1,11 @@
+Corwin Perren - Concurrency HW 4
+
+To make this program on the os server, cd into this directory and run "make".
+
+To run, type "./concurrency4" into the terminal.
+
+To change the number of chairs in the shop, edit the line in main.c, seen below,
+to have the number of desired waiting room chairs.
+
+#define NUM_BARBERSHOP_WAITING_ROOM_CHAIRS 5
+