#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#include <pthread.h>
#define MYPORT 8080 // the port users will be connecting to
#define BACKLOG 10 // how many pending connections queue will hold
#define MAXDATASIZE 1000
//*********************************************************************
void sigchld_handler(int s)
{
while(wait(NULL) > 0);
}
//*********************************************************************
//---------------------------httpRequest Method------------------------
void* httpRequest(void* data)
{
int me = *((int*)data);
char buf[MAXDATASIZE],requestLine[100],tmp[20];
int a=0,k=0,b=0,received=-1;
//Get the Header lines from the client
if ((received = recv(me, buf, 100, 0)) < 0)
{
perror("Failed to receive initial bytes from client");
}
buf[received-1]='\0';
//Extract the request line.
while(buf[a]!= '\n')
requestLine[a]=buf[a++];
//Get the "GET" word.
while(requestLine[b] != ' ')
tmp[b]= requestLine[b++];
if (strcmp(tmp,"GET")==0)
{
//Extract the file name.
char *fileName,*fl1,*fl2;
fl1=strpbrk(requestLine,"/");
fl2=strtok(fl1," ");
fileName=strpbrk(fl2,"/");
//Document root
char document_root[10]="./html";
//Prepend the path of the Document root so that the
//file request is within the Document root
if(strcmp(fileName,"/")==0)
strcpy(fileName,strcat(document_root,"/index.html"));
else
strcpy(fileName,strcat(document_root,fileName));
//Open the requested file.
FILE *fp;
int file_exist=1;
fp=fopen(fileName, "r");
if (fp==NULL)
file_exist=0;
//Extract the extension and assign content type of that file-----------------------------------------------------------------
char *filetype;
char *type;
int s='.';
filetype=strrchr(fileName,s);
if((strcmp(filetype,".htm"))==0 || (strcmp(filetype,".html"))==0)
type="text/html";
else if((strcmp(filetype,".jpg"))==0)
type="image/jpeg";
else if(strcmp(filetype,".gif")==0)
type="image/gif";
else if(strcmp(filetype,".txt")==0)
type="text/plain";
else if((strcmp(filetype,".ram")==0) || (strcmp(filetype,".ra")==0))
type="audio/x-pn-realaudio";
else
type="application/octet-stream";
char statusLine[100]="HTTP/1.0";
char contentTypeLine[100]="Content-type: ";
char entityBody[100]="<html>";
if(file_exist==1)
{
//send status line and the content type line
strcpy(statusLine,strcat(statusLine,"200 OK"));
strcpy(statusLine,strcat(statusLine,"\r\n"));
strcpy(contentTypeLine,strcat(contentTypeLine,type));
strcpy(contentTypeLine,strcat(contentTypeLine,"\r\n"));
}
else
{
strcpy(statusLine,strcat(statusLine,"404 Not Found"));
strcpy(statusLine,strcat(statusLine,"\r\n"));
//send a blank line to indicate the end of the header lines
strcpy(contentTypeLine,strcat(contentTypeLine,"NONE"));
strcpy(contentTypeLine,strcat(contentTypeLine,"\r\n"));
//send the entity body
strcpy(entityBody,strcat(entityBody,"<HEAD><TITLE>404 Not Found</TITLE></HEAD>"));
strcpy(entityBody,strcat(entityBody,"<BODY>Not Found</BODY></html>"));
strcpy(entityBody,strcat(entityBody,"\r\n"));
}
//send the status line and content type line.
if ((send(me, statusLine,strlen(statusLine), 0) == -1) ||
(send(me, contentTypeLine, strlen(contentTypeLine),0) == -1) ||
(send(me,"\r\n", strlen("\r\n"), 0) == -1))
perror("Failed to send bytes to client");
//send the entity body
if (file_exist)
{
wchar_t read_char[1];
while((read_char[0]=fgetc(fp))!=EOF)
{
if(send(me,read_char,sizeof(char),0) == -1)
perror("Failed to send bytes to client");
}
}
else
{
if (send(me, entityBody, 100, 0) == -1)
perror("Failed to send bytes to client");
}
close(me); // Close the connection.
pthread_exit(NULL); //Existing from the threads.
}
else
printf("Warning message\n");
}
//****************************************************************************************************************
//Main Method------------------------------------------------------------------
int main (void)
{
int sockfd, new_fd; // listen on sock_fd, new connection on new_fd
struct sockaddr_in my_addr; // my address information
struct sockaddr_in their_addr; // connector's address information
int sin_size;
struct sigaction sa;
int yes=1;
pthread_t p_thread[3000];
int thr_id,i=0;
//Create the parent socket.
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(1);
}
//Handy debugging trick that lets
if (setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(int)) == -1) {
perror("setsockopt");
exit(1);
}
//Build the server's Inernet address.
// bzero((char *) &my_addr, sizeof(my_addr));
my_addr.sin_family = AF_INET; // host byte order
my_addr.sin_port = htons(MYPORT); // short, network byte order
my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP
memset(&(my_addr.sin_zero), '\0', 8); // zero the rest of the struct
//Binding
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr))== -1) {
perror("bind");
exit(1);
}
//Make this socket ready to accept connection requests.
if (listen(sockfd, BACKLOG) == -1) {
perror("listen");
exit(1);
}
sa.sa_handler = sigchld_handler; // read all dead processes
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if (sigaction(SIGCHLD, &sa, NULL) == -1) {
perror("sigaction");
exit(1);
}
while(1)
{ // main accept() loop
sin_size = sizeof(struct sockaddr_in);
if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr,&sin_size)) == -1) {
perror("accept");
continue;
}
//Creates threads.
thr_id = pthread_create(&p_thread[i++],NULL,httpRequest,(void*)&new_fd);
}
return 0;
}
MULTI THREADED WEB SERVER IN C SOURCE CODE(LODE PAGES FROM GIVEN FOLDER LOCATION AND PUBLISH THEM)
Interrupts' and their usage in pic microchip circuit design
1. What is an interrupt?
Basically CPU executes the instructions of the program one by one, doing what it is told in a precise and linear way. An interrupt disturbs this order. Coming maybe when least expected, its function is to alert the CPU that some significant external event has happened, to stop it from what it is doing and force it (at greatest speed possible) to respond to what has happened. Originally this was applied to allow emergency external events to get the attention of the CPU, emergencies like power failure, the system overheating or major failure of a subsystem. Then CPU takes necessary actions2. What is an ISR? What command is used in PIC to return from an ISR?
ISR is interrupt service routine so that basically handle the necessary actions should be taken when some interrupt happens. We can use ISR by configuring following few steps
ü Start the ISR at the interrupt vector, location 0004
ü Enable the interrupt that is to be used, by setting the enable bit in the INTCON register
ü Set the Global Enable bit, GIE
ü Clear the interrupt flag within the ISREnd the ISR with a retfie instruction. RETFIE is exactly like a return, but it also sets the global interrupt enable (GIE). When a hardware interrupt occurs, it clears GIE and executes what amounts to a CALL instruction. Using RETFIE allows us to enable interrupts and return to the main program all in one step
3. What is Interrupt Latency?
The purpose of the interrupt is to attract the attention of the CPU quickly, but actually how quickly does this happen? The time between the interrupt occurring and the CPU responding to it is called the latency. Actually this is based on hardware configurations of the device4. What are Interrupt flag bits and mask bits?
Flag bits-The occurrence of the interrupt, even if it is only momentary, is thus recorded. The output of the bistable, the latched version of the interrupt, is called the interrupt flag. This is then gated with an enable signal, Interrupt is enable. Basically we checked flag bits to detect weather interrupt is occurs or not
Mask bits- These bits are used to select which interrupts can be enable. Some interrupts can turn off and turn on. So do that we can use those bits. The action of disabling an interrupt is sometimes called masking. some microcontrollers have interrupts that cannot be masked. These are always external and are used to connect to external interrupt signals of the greatest importance
5. What is the bit that needs to be set in order to enable External interrupt on RBO (0th bit of PortB)?
bsf intcon,inte
And we must select global interrupt enable bit6. What are timers? What is a pre-scalar?
We can use timers to maintain periodic events. Timers provide the timing for a range of activity such as motor controlling and various other applications
The external input path includes the option of inverting the signal with the Exclusive OR gate, the inversion being controlled by bit T0SE which is appear in option register. The output of the first multiplexer branches before reaching a second multiplexer. This selects either a direct path or the path taken through a programmable prescaler.we can set 1 trigger for 255 triggers by setting this
7. What is a watch dog timer?
Big problem of computer system is that the software fails in some way and that the system locks up or becomes unresponsive. In a desktop computer such lock-up can be annoying and one would normally have to reboot. In an embedded system it can be disastrous, as there may be no user to notice that there is something wrong and maybe no user interface anyway. If we enable this timer it’s perioditically counting up and it reaches top value of it then it reset the program (reset means go to the beginning of the program) if we neet to avoid reset we have to clear that by our program time to time.
Timer0 interrupt generation Assembly code for microchip pic16f877
list p=16f877
include <dev_fam.inc> ;this file is checked and corrected
include <math16.inc> ;
include <p16f877.inc>
;**********************************************************
;DEFINITIONS:CONSTANTS
FALSE equ 0
TRUE equ 1
PP0 equ b'00000000' ;PIC program page
PP1 equ b'00001000'
PP2 equ b'00010000'
PP3 equ b'00011000'
;------------------------------------------------------------
; RAM variables
ORG 0X20
;-------------------------------------------------------------
PROGRAMPAGE set PP0
org 0x00 ;RESET VECTOR
goto start ;RUN main routine
org 0x04 ;Interrupt VECTOR
;you can enter your interrupt check routines here
goto ISR
;------------------------------------------------------------------
org 0xA0
start
;code for Initialization of Timer0 and other bits
BANKSEL INTCON ;BANK2
MOVLW 0xA0
MOVWF INTCON ;Global interrupt and TMR0 interrupt enabled
;set timer 0
banksel TMR0
movlw b'00000000'
movwf TMR0
;get one timer 0 inturrupt after 256 triggers
banksel OPTION_REG
movlw b'10000110'
movwf OPTION_REG
;set port B as output
banksel TRISB
movlw b'11110000'
movwf TRISB
banksel PORTB
movlw b'00000000'
movwf PORTB
loop
;loops forever until inturrupts come
goto loop
ISR
;handling the interrupt
comf PORTB,1 ; Toggle Port B
BANKSEL INTCON ;BANK0
BCF INTCON,2 ;CLEAR INTERRUPT FLAG
Retfie ;return and set global in turrupt enable
end
--------------------------------------------------------------------------
Subscribe to:
Posts (Atom)
Empowering the Future of API Management: Unveiling the Journey of WSO2 API Platform for Kubernetes (APK) Project and the Anticipated Alpha Release
Introduction In the ever-evolving realm of API management, our journey embarked on the APK project eight months ago, and now, with great a...
