LAB 4 IS DONE.

lab/kern/env.h

@@ -0,0 +1,36 @@
+/* See COPYRIGHT for copyright information. */
+
+#ifndef JOS_KERN_ENV_H
+#define JOS_KERN_ENV_H
+
+#include <inc/env.h>
+#include <kern/cpu.h>
+
+extern struct Env *envs;		// All environments
+#define curenv (thiscpu->cpu_env)		// Current environment
+extern struct Segdesc gdt[];
+
+void	env_init(void);
+void	env_init_percpu(void);
+int	env_alloc(struct Env **e, envid_t parent_id);
+void	env_free(struct Env *e);
+void	env_create(uint8_t *binary, enum EnvType type);
+void	env_destroy(struct Env *e);	// Does not return if e == curenv
+
+int	envid2env(envid_t envid, struct Env **env_store, bool checkperm);
+// The following two functions do not return
+void	env_run(struct Env *e) __attribute__((noreturn));
+void	env_pop_tf(struct Trapframe *tf) __attribute__((noreturn));
+
+// Without this extra macro, we couldn't pass macros like TEST to
+// ENV_CREATE because of the C pre-processor's argument prescan rule.
+#define ENV_PASTE3(x, y, z) x ## y ## z
+
+#define ENV_CREATE(x, type)						\
+	do {								\
+		extern uint8_t ENV_PASTE3(_binary_obj_, x, _start)[];	\
+		env_create(ENV_PASTE3(_binary_obj_, x, _start),		\
+			   type);					\
+	} while (0)
+
+#endif // !JOS_KERN_ENV_H