Clean up memlayout.h

Get rid of last instances of linear address and "la"
Get ready for detecting physical memory dynamically

1 files changed, 8 insertions, 6 deletions

diff --git a/mmu.h b/mmu.h
index 9ab581a..e5a4f1e 100644
--- a/mmu.h
+++ b/mmu.h
@@ -100,32 +100,34 @@ struct segdesc {
 #define STS_IG32    0xE     // 32-bit Interrupt Gate
 #define STS_TG32    0xF     // 32-bit Trap Gate
 
-// A linear address 'la' has a three-part structure as follows:
+// A virtual address 'la' has a three-part structure as follows:
 //
 // +--------10------+-------10-------+---------12----------+
 // | Page Directory |   Page Table   | Offset within Page  |
 // |      Index     |      Index     |                     |
 // +----------------+----------------+---------------------+
-//  \--- PDX(la) --/ \--- PTX(la) --/ 
+//  \--- PDX(va) --/ \--- PTX(va) --/ 
 
 // page directory index
-#define PDX(la)		(((uint)(la) >> PDXSHIFT) & 0x3FF)
+#define PDX(va)		(((uint)(va) >> PDXSHIFT) & 0x3FF)
 
 // page table index
-#define PTX(la)		(((uint)(la) >> PTXSHIFT) & 0x3FF)
+#define PTX(va)		(((uint)(va) >> PTXSHIFT) & 0x3FF)
 
-// construct linear address from indexes and offset
+// construct virtual address from indexes and offset
 #define PGADDR(d, t, o)	((uint)((d) << PDXSHIFT | (t) << PTXSHIFT | (o)))
 
 // Page directory and page table constants.
 #define NPDENTRIES	1024		// page directory entries per page directory
 #define NPTENTRIES	1024		// page table entries per page table
+#define PGSIZE          4096            // bytes mapped by a page
 
+#define PGSHIFT         12              // log2(PGSIZE)
 #define PTXSHIFT	12		// offset of PTX in a linear address
 #define PDXSHIFT	22		// offset of PDX in a linear address
 
 #define PGROUNDUP(sz)  (((sz)+PGSIZE-1) & ~(PGSIZE-1))
-#define PGROUNDDOWN(a) ((char*)((((unsigned int)(a)) & ~(PGSIZE-1))))
+#define PGROUNDDOWN(a) (((a)) & ~(PGSIZE-1))
 
 // Page table/directory entry flags.
 #define PTE_P		0x001	// Present