From 5213ffa9e2ff09d8ff609b61a7cf589d03050477 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Martin=20Ho=C5=99e=C5=88ovsk=C3=BD?=
 <Martin.Horenovsky@gmail.com>
Date: Wed, 21 Aug 2013 20:21:43 +0200
Subject: [PATCH 1/1] Adds a library with pair of functions to put load on CPU.

The implementation is, with the exception of error handling, feature complete, but not well commented.
---
 rtems/gw/libs/Makefile     |  14 +++++
 rtems/gw/libs/Makefile.omk |   5 ++
 rtems/gw/libs/load.c       | 116 +++++++++++++++++++++++++++++++++++++
 rtems/gw/libs/load.h       |   7 +++
 4 files changed, 142 insertions(+)
 create mode 100644 rtems/gw/libs/Makefile
 create mode 100644 rtems/gw/libs/Makefile.omk
 create mode 100644 rtems/gw/libs/load.c
 create mode 100644 rtems/gw/libs/load.h

diff --git a/rtems/gw/libs/Makefile b/rtems/gw/libs/Makefile
new file mode 100644
index 0000000..76b56fd
--- /dev/null
+++ b/rtems/gw/libs/Makefile
@@ -0,0 +1,14 @@
+# Generic directory or leaf node makefile for OCERA make framework
+
+ifndef MAKERULES_DIR
+MAKERULES_DIR := $(shell ( old_pwd="" ;  while [ ! -e Makefile.rules ] ; do if [ "$$old_pwd" = `pwd`  ] ; then exit 1 ; else old_pwd=`pwd` ; cd -L .. 2>/dev/null ; fi ; done ; pwd ) )
+endif
+
+ifeq ($(MAKERULES_DIR),)
+all : default
+.DEFAULT::
+	@echo -e "\nThe Makefile.rules has not been found in this or parent directory\n"
+else
+include $(MAKERULES_DIR)/Makefile.rules
+endif
+
diff --git a/rtems/gw/libs/Makefile.omk b/rtems/gw/libs/Makefile.omk
new file mode 100644
index 0000000..dd4d803
--- /dev/null
+++ b/rtems/gw/libs/Makefile.omk
@@ -0,0 +1,5 @@
+lib_LIBRARIES = load
+
+include_HEADERS = load.h
+
+load_SOURCES = load.c
diff --git a/rtems/gw/libs/load.c b/rtems/gw/libs/load.c
new file mode 100644
index 0000000..ba7fac4
--- /dev/null
+++ b/rtems/gw/libs/load.c
@@ -0,0 +1,116 @@
+/*
+* Implements simple producer/consumer thread pair to cause load on the CPU.
+* 
+* Used in benchmarking the CAN gateway.
+*
+* Co-opted from http://support.dce.felk.cvut.cz/pos/cv3/src/semaphore.html. 
+*/
+
+#include <stdio.h>
+
+#include <pthread.h>
+#include <semaphore.h>
+
+#include "load.h"
+
+
+static void* produce(void* arg);
+static void* consume(void* arg);
+
+/* semaphores for consumer/producer pair */
+static sem_t produced, consumed;
+/* pthread handles for the loader */
+static pthread_t consumer, producer;
+static int n = 0;
+static char running = 0;
+
+static void* produce(void* arg){
+    while (1) {
+            sem_wait(&consumed);
+            n++;  /* increment n by 1 */
+            sem_post(&produced);
+            pthread_testcancel();
+    }
+    return NULL;
+}       
+
+static void* consume(void* arg){
+    while (1) {
+            sem_wait(&produced);
+            n--; /* aaand decrement */
+            sem_post(&consumed);
+            pthread_testcancel();
+    }
+    return NULL;
+}
+
+int start_thread_load(){
+    if (running == 0){
+        printf("Attempting to start load.\n");
+        int res;
+        running = 1;
+        res = sem_init(&consumed, 0, 0);
+        if (res < 0){
+            printf("Couldn't initialize consumed semaphore.\n");
+            return 1;
+        }
+        res = sem_init(&produced, 0, 1);
+        if (res < 0){
+            printf("Couldn't initialize produced semaphore.\n");
+            return 1;
+        }
+        
+        res = pthread_create(&producer, NULL, produce, NULL);
+        if (res < 0){
+            printf("Couldn't create producer thread.\n");
+            return 1;
+        }
+        
+        res = pthread_create(&consumer, NULL, consume, NULL);
+        if (res < 0){
+            printf("Couldn't create consumer thread.\n");
+            return 1;
+        }
+    
+        pthread_detach(producer);
+        pthread_detach(consumer);
+        printf("Load started succesfully.\n");
+        return 0;
+    } else {
+        printf("Load is already running.\n");
+        return 0;
+    }
+}
+
+/*
+* This function stops threads loading the CPU and destroys associated semaphores. 
+* 
+* No error handling currently, only tries to report errors.
+* 
+*/
+int end_thread_load(){
+    if (running == 1){
+        int res;
+        printf("Attempting to cancel producer thread.\n");
+        res = pthread_cancel(producer);
+        if (res != 0){
+            printf("Failed.\n");
+            /* Not sure what to do with error here, will have to figure out later. */
+        }
+        printf("Attempting to cancel consumer thread.\n");
+        res = pthread_cancel(consumer);
+        if (res != 0){
+            printf("Failed.\n");
+        }
+        printf("Preparing to destroy semaphores.\n");
+        sleep(1);
+        sem_destroy(&produced);
+        sem_destroy(&consumed);
+        running = 0;
+        printf("Finished.\n");
+        return 0;
+    } else {
+        printf("Load is not running.\n");
+        return 0;
+    }
+}
\ No newline at end of file
diff --git a/rtems/gw/libs/load.h b/rtems/gw/libs/load.h
new file mode 100644
index 0000000..b355c24
--- /dev/null
+++ b/rtems/gw/libs/load.h
@@ -0,0 +1,7 @@
+#ifndef __CPU_LOAD_H_
+#define __CPU_LOAD_H_
+
+int start_thread_load();
+int end_thread_load();
+
+#endif
\ No newline at end of file
-- 
2.39.2