1 files changed, 89 insertions, 0 deletions
diff --git a/src/threads/vaddr.h b/src/threads/vaddr.h
new file mode 100644
index 0000000..184c824
--- /dev/null
+++ b/src/threads/vaddr.h
@@ -0,0 +1,89 @@
+#ifndef THREADS_VADDR_H
+#define THREADS_VADDR_H
+
+#include <debug.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "threads/loader.h"
+
+/* Functions and macros for working with virtual addresses.
+
+   See pte.h for functions and macros specifically for x86
+   hardware page tables. */
+
+#define BITMASK(SHIFT, CNT) (((1ul << (CNT)) - 1) << (SHIFT))
+
+/* Page offset (bits 0:12). */
+#define PGSHIFT 0                          /* Index of first offset bit. */
+#define PGBITS  12                         /* Number of offset bits. */
+#define PGSIZE  (1 << PGBITS)              /* Bytes in a page. */
+#define PGMASK  BITMASK(PGSHIFT, PGBITS)   /* Page offset bits (0:12). */
+
+/* Offset within a page. */
+static inline unsigned pg_ofs (const void *va) {
+  return (uintptr_t) va & PGMASK;
+}
+
+/* Virtual page number. */
+static inline uintptr_t pg_no (const void *va) {
+  return (uintptr_t) va >> PGBITS;
+}
+
+/* Round up to nearest page boundary. */
+static inline void *pg_round_up (const void *va) {
+  return (void *) (((uintptr_t) va + PGSIZE - 1) & ~PGMASK);
+}
+
+/* Round down to nearest page boundary. */
+static inline void *pg_round_down (const void *va) {
+  return (void *) ((uintptr_t) va & ~PGMASK);
+}
+
+/* Base address of the 1:1 physical-to-virtual mapping.  Physical
+   memory is mapped starting at this virtual address.  Thus,
+   physical address 0 is accessible at PHYS_BASE, physical
+   address address 0x1234 at (uint8_t *) PHYS_BASE + 0x1234, and
+   so on.
+
+   This address also marks the end of user programs' address
+   space.  Up to this point in memory, user programs are allowed
+   to map whatever they like.  At this point and above, the
+   virtual address space belongs to the kernel. */
+#define	PHYS_BASE ((void *) LOADER_PHYS_BASE)
+
+/* Returns true if VADDR is a user virtual address. */
+static inline bool
+is_user_vaddr (const void *vaddr) 
+{
+  return vaddr < PHYS_BASE;
+}
+
+/* Returns true if VADDR is a kernel virtual address. */
+static inline bool
+is_kernel_vaddr (const void *vaddr) 
+{
+  return vaddr >= PHYS_BASE;
+}
+
+/* Returns kernel virtual address at which physical address PADDR
+   is mapped. */
+static inline void *
+ptov (uintptr_t paddr)
+{
+  ASSERT ((void *) paddr < PHYS_BASE);
+
+  return (void *) (paddr + PHYS_BASE);
+}
+
+/* Returns physical address at which kernel virtual address VADDR
+   is mapped. */
+static inline uintptr_t
+vtop (const void *vaddr)
+{
+  ASSERT (is_kernel_vaddr (vaddr));
+
+  return (uintptr_t) vaddr - (uintptr_t) PHYS_BASE;
+}
+
+#endif /* threads/vaddr.h */