define memory layout (if there was a layout)

1 files changed, 37 insertions, 3 deletions

diff --git a/src/defs.rs b/src/defs.rs
index 3c1ff57..cec17c9 100644
--- a/src/defs.rs
+++ b/src/defs.rs
@@ -1,13 +1,47 @@
 pub struct Mem;
+pub struct VAddr(u64);
+
 impl Mem {
 	// units
 	pub const K: usize = 1024;
 	pub const M: usize = 1024 * Mem::K;
 	pub const G: usize = 1024 * Mem::M;
-	// physical memory
-	pub const PHY_TOP: usize = 128 * Mem::M; // qemu defaults to 128 MiB phy Memory
+	// physical memory layout: qemu defaults to 128 MiB phy Memory
+	pub const PHY_TOP: usize = 128 * Mem::M;
+	// 4 lv 4K paging
 	pub const PAGE_SIZE: usize = 0x1000;
 	pub const PAGE_SHIFT: usize = 12;
-	pub const PHY_PAGES: usize = Mem::PHY_TOP >> Mem::PAGE_SHIFT;
 	pub const PAGE_MASK: u64 = 0xfff;
+	pub const L0_SHIFT: u8 = 39;
+	pub const L0_MASK: u64 = 0x1ff << Mem::L0_SHIFT;
+	pub const L1_SHIFT: u8 = 30;
+	pub const L1_MASK: u64 = 0x1ff << Mem::L1_SHIFT;
+	pub const L2_SHIFT: u8 = 21;
+	pub const L2_MASK: u64 = 0x1ff << Mem::L2_SHIFT;
+	pub const L3_SHIFT: u8 = 12;
+	pub const L3_MASK: u64 = 0x1ff << Mem::L3_SHIFT;
+	pub const PHY_PAGES: usize = Mem::PHY_TOP >> Mem::PAGE_SHIFT;
+	// size of frame allocator bitmap: number of physical frames / 8 for 128M
+	// memory (37268) 4k pages, 37268 bits are needed, hence
+	// 4096 bytes, exactly one page!
+	pub const PHY_BM_SIZE: usize = Mem::PHY_PAGES >> 3;
+}
+
+impl VAddr {
+	pub fn roundup_4k(&self) {
+		todo!()
+	}
+	pub fn rounddown_4k(&self) {
+		todo!()
+	}
+	pub fn page_number(&self) -> u64 {
+		self.0 >> Mem::PAGE_SHIFT
+	}
 }
+
+// PHY_TOP			128M
+// ~				free frames
+// PMA::bitmap		+ PHY_BM_SIZE
+// ~				___KERNEL_END__
+// KERNEL IMAGE
+// KERNEL START		1 M