add sys_printchar

kern/arch/mips/syscall/syscall.c

@@ -110,6 +110,10 @@ void syscall(struct trapframe *tf) {
     thread_exit();
     break;
 
+  case SYS_printchar:
+    err = sys_printchar((char)tf->tf_a0);
+    break;
+
     /* Add stuff here */
 
   default:

kern/conf/conf.kern

@@ -379,6 +379,7 @@ file      vfs/devnull.c
 file      syscall/loadelf.c
 file      syscall/runprogram.c
 file      syscall/time_syscalls.c
+file      syscall/printchar.c
 
 #
 # Startup and initialization

kern/include/kern/syscall.h

@@ -94,6 +94,7 @@
 // #define SYS_getpriority 38
 // #define SYS_setpriority 39
 //                               (process groups, sessions, and job control)
+#define SYS_printchar 41
 // #define SYS_getpgid    40
 // #define SYS_setpgid    41
 // #define SYS_getsid     42

kern/include/syscall.h

@@ -57,4 +57,6 @@ __DEAD void enter_new_process(int argc, userptr_t argv, userptr_t env,
 int sys_reboot(int code);
 int sys___time(userptr_t user_seconds, userptr_t user_nanoseconds);
 
+int sys_printchar(char c);
+
 #endif /* _SYSCALL_H_ */

kern/syscall/printchar.c

@@ -0,0 +1,7 @@
+#include <types.h>
+#include <lib.h>
+#include <syscall.h>
+int sys_printchar(char c) {
+  kprintf("%c", c);
+  return 0;
+}

userland/include/unistd.h

@@ -156,4 +156,6 @@ int execvp(const char *prog, char *const *args); /* calls execv */
 char *getcwd(char *buf, size_t buflen);          /* calls __getcwd */
 time_t time(time_t *seconds);                    /* calls __time */
 
+int printchar(char c);
+
 #endif /* _UNISTD_H_ */

userland/testbin/Makefile

@@ -8,7 +8,7 @@ TOP=../..
 SUBDIRS=add argtest badcall bigexec bigfile bigfork bigseek bloat conman \
 	crash ctest dirconc dirseek dirtest f_test factorial farm faulter \
 	filetest forkbomb forktest frack hash hog huge \
-	malloctest matmult multiexec palin parallelvm poisondisk psort \
+	malloctest matmult multiexec palin parallelvm poisondisk printchartest psort \
 	randcall redirect rmdirtest rmtest \
 	sbrktest schedpong sort sparsefile tail tictac triplehuge \
 	triplemat triplesort usemtest zero

userland/testbin/printchartest/Makefile

@@ -0,0 +1,11 @@
+# Makefile for printchartest
+
+TOP=../../..
+.include "$(TOP)/mk/os161.config.mk"
+
+PROG=printchartest
+SRCS=printchartest.c
+BINDIR=/testbin
+
+.include "$(TOP)/mk/os161.prog.mk"
+

userland/testbin/printchartest/printchartest.c

@@ -0,0 +1,17 @@
+#include <unistd.h>
+
+extern int printchar(char c);
+
+int main() {
+
+  printchar('C');
+  printchar('S');
+  printchar('E');
+  printchar('4');
+  printchar('0');
+  printchar('0');
+  printchar('1');
+  printchar('\n');
+
+  return 0;
+}