Merge branch 'lab3' into lab4

lib/libmain.c

@@ -13,7 +13,8 @@ libmain(int argc, char **argv)
 {
 	// set thisenv to point at our Env structure in envs[].
 	// LAB 3: Your code here.
-	thisenv = 0;
+	envid_t id = sys_getenvid();
+	thisenv = &envs[ENVX(id)];
 
 	// save the name of the program so that panic() can use it
 	if (argc > 0)

lib/printfmt.c

@@ -207,11 +207,9 @@ vprintfmt(void (*putch)(int, void*), void *putdat, const char *fmt, va_list ap)
 
 		// (unsigned) octal
 		case 'o':
-			// LAB 1: Replace this with your code.
-			putch('X', putdat);
-			putch('X', putdat);
-			putch('X', putdat);
-			break;
+			num = getuint(&ap, lflag);
+			base = 8;
+			goto number;
 
 		// pointer
 		case 'p':

lib/syscall.c

@@ -2,6 +2,7 @@
 
 #include <inc/syscall.h>
 #include <inc/lib.h>
+#include <inc/x86.h>
 
 static inline int32_t
 syscall(int num, int check, uint32_t a1, uint32_t a2, uint32_t a3, uint32_t a4, uint32_t a5)
@@ -37,16 +38,30 @@ syscall(int num, int check, uint32_t a1, uint32_t a2, uint32_t a3, uint32_t a4,
 	return ret;
 }
 
+int32_t
+fast_syscall(int num, uint32_t a1, uint32_t a2, uint32_t a3, uint32_t a4) {
+	asm volatile(
+			"push %%ebp\n\t"
+			"mov %%esp, %%ebp\n\t"
+			"lea syscall_ret_%=, %%esi\n\t"
+			"sysenter\n\t"
+			"syscall_ret_%=: pop %%ebp\n\t"
+			: "+a" (num)
+			: "d" (a1), "c" (a2), "b" (a3), "D" (a4)
+			: "esi");
+	return num;
+}
+
 void
 sys_cputs(const char *s, size_t len)
 {
-	syscall(SYS_cputs, 0, (uint32_t)s, len, 0, 0, 0);
+	fast_syscall(SYS_cputs, (uint32_t)s, len, 0, 0);
 }
 
 int
 sys_cgetc(void)
 {
-	return syscall(SYS_cgetc, 0, 0, 0, 0, 0, 0);
+	return fast_syscall(SYS_cgetc, 0, 0, 0, 0);
 }
 
 int