feat(ppu): implement VRAM

src/ppu.zig

@@ -0,0 +1,47 @@
+const std = @import("std");
+
+const Allocator = std.mem.Allocator;
+
+pub const Ppu = struct {
+    vram: Vram,
+
+    pub fn init(alloc: Allocator) !@This() {
+        return @This(){
+            .vram = try Vram.init(alloc),
+        };
+    }
+};
+
+const Vram = struct {
+    buf: []u8,
+
+    fn init(alloc: Allocator) !@This() {
+        return @This(){
+            .buf = try alloc.alloc(u8, 0x18000),
+        };
+    }
+
+    pub inline fn get32(self: *const @This(), idx: usize) u32 {
+        return (@as(u32, self.buf[idx + 3]) << 24) | (@as(u32, self.buf[idx + 2]) << 16) | (@as(u32, self.buf[idx + 1]) << 8) | (@as(u32, self.buf[idx]));
+    }
+
+    pub inline fn set32(self: *@This(), idx: usize, word: u32) void {
+        self.buf[idx + 3] = @truncate(u8, word >> 24);
+        self.buf[idx + 2] = @truncate(u8, word >> 16);
+        self.buf[idx + 1] = @truncate(u8, word >> 8);
+        self.buf[idx] = @truncate(u8, word);
+    }
+
+    pub inline fn get16(self: *const @This(), idx: usize) u16 {
+        return (@as(u16, self.buf[idx + 1]) << 8) | @as(u16, self.buf[idx]);
+    }
+
+    pub inline fn set16(self: *@This(), idx: usize, halfword: u16) void {
+        self.buf[idx + 1] = @truncate(u8, halfword >> 8);
+        self.buf[idx] = @truncate(u8, halfword);
+    }
+
+    pub inline fn get8(self: *const @This(), idx: usize) u8 {
+        return self.buf[idx];
+    }
+};