pingpong finished

Makefile

@@ -86,7 +86,7 @@ LD = $(TOOLPREFIX)ld
 OBJCOPY = $(TOOLPREFIX)objcopy
 OBJDUMP = $(TOOLPREFIX)objdump
 
-CFLAGS = -Wall -Werror -O -fno-omit-frame-pointer -ggdb -gdwarf-2
+CFLAGS = -Wall -Werror -O2 -fno-omit-frame-pointer -ggdb -gdwarf-2
 
 ifdef LAB
 LABUPPER = $(shell echo $(LAB) | tr a-z A-Z)
@@ -189,6 +189,7 @@ UPROGS=\
 	$U/_wc\
 	$U/_zombie\
 	$U/_sleep\
+	$U/_pingpong\
 
 
 

user/pingpong.c

@@ -0,0 +1,21 @@
+#include "kernel/types.h"
+#include "user/user.h"
+
+int main(int argc, char *argv[]) {
+  int proc_f2s[2], proc_s2f[2];
+  char buffer[8];
+  pipe(proc_f2s);
+  pipe(proc_s2f);
+
+  if (fork() == 0) {
+    read(proc_s2f[0], buffer, 4);
+    printf("%d: received %s\n", getpid(), buffer);
+    write(proc_f2s[1], "pong", strlen("pong"));
+  } else {
+    write(proc_s2f[1], "ping", strlen("ping"));
+    read(proc_f2s[0], buffer, 4);
+    printf("%d: received %s\n", getpid(), buffer);
+  }
+
+  exit(0);
+}

user/ulib.c

@@ -1,22 +1,18 @@
-#include "kernel/types.h"
-#include "kernel/stat.h"
 #include "kernel/fcntl.h"
+#include "kernel/stat.h"
+#include "kernel/types.h"
 #include "user/user.h"
 
 //
 // wrapper so that it's OK if main() does not call exit().
 //
-void
+void _main() {
-_main()
-{
   extern int main();
   main();
   exit(0);
 }
 
-char*
+char *strcpy(char *s, const char *t) {
-strcpy(char *s, const char *t)
-{
   char *os;
 
   os = s;
@@ -25,17 +21,13 @@ strcpy(char *s, const char *t)
   return os;
 }
 
-int
+int strcmp(const char *p, const char *q) {
-strcmp(const char *p, const char *q)
-{
   while (*p && *p == *q)
     p++, q++;
   return (uchar)*p - (uchar)*q;
 }
 
-uint
+uint strlen(const char *s) {
-strlen(const char *s)
-{
   int n;
 
   for (n = 0; s[n]; n++)
@@ -43,9 +35,7 @@ strlen(const char *s)
   return n;
 }
 
-void*
+void *memset(void *dst, int c, uint n) {
-memset(void *dst, int c, uint n)
-{
   char *cdst = (char *)dst;
   int i;
   for (i = 0; i < n; i++) {
@@ -54,18 +44,14 @@ memset(void *dst, int c, uint n)
   return dst;
 }
 
-char*
+char *strchr(const char *s, char c) {
-strchr(const char *s, char c)
-{
   for (; *s; s++)
     if (*s == c)
       return (char *)s;
   return 0;
 }
 
-char*
+char *gets(char *buf, int max) {
-gets(char *buf, int max)
-{
   int i, cc;
   char c;
 
@@ -81,9 +67,7 @@ gets(char *buf, int max)
   return buf;
 }
 
-int
+int stat(const char *n, struct stat *st) {
-stat(const char *n, struct stat *st)
-{
   int fd;
   int r;
 
@@ -95,9 +79,7 @@ stat(const char *n, struct stat *st)
   return r;
 }
 
-int
+int atoi(const char *s) {
-atoi(const char *s)
-{
   int n;
 
   n = 0;
@@ -106,9 +88,7 @@ atoi(const char *s)
   return n;
 }
 
-void*
+void *memmove(void *vdst, const void *vsrc, int n) {
-memmove(void *vdst, const void *vsrc, int n)
-{
   char *dst;
   const char *src;
 
@@ -126,9 +106,7 @@ memmove(void *vdst, const void *vsrc, int n)
   return vdst;
 }
 
-int
+int memcmp(const void *s1, const void *s2, uint n) {
-memcmp(const void *s1, const void *s2, uint n)
-{
   const char *p1 = s1, *p2 = s2;
   while (n-- > 0) {
     if (*p1 != *p2) {
@@ -140,8 +118,6 @@ memcmp(const void *s1, const void *s2, uint n)
   return 0;
 }
 
-void *
+void *memcpy(void *dst, const void *src, uint n) {
-memcpy(void *dst, const void *src, uint n)
-{
   return memmove(dst, src, n);
 }

user/user.h

@@ -1,3 +1,4 @@
+#include "kernel/types.h"
 struct stat;
 
 // system calls