From d4d5c6ff9534d155e4472e40fb3266ae8d495a37 Mon Sep 17 00:00:00 2001
From: Natasha England-Elbro <natasha@natashaee.me>
Date: Thu, 1 Feb 2024 15:05:40 +0000
Subject: [PATCH] fix: crashing citra

---
 citro3d/examples/cube.rs | 24 ++++++++++++++----------
 citro3d/src/lib.rs       | 29 ++++++++++++++++++++++-------
 citro3d/src/util.rs      |  6 ++++++
 3 files changed, 42 insertions(+), 17 deletions(-)
 create mode 100644 citro3d/src/util.rs

diff --git a/citro3d/examples/cube.rs b/citro3d/examples/cube.rs
index 73c074c..b8ff063 100644
--- a/citro3d/examples/cube.rs
+++ b/citro3d/examples/cube.rs
@@ -111,7 +111,7 @@ fn main() {
             y: v[1],
             z: v[2],
         },
-        color: Vec3::new(i as f32 % 1., i as f32 % 1., i as f32 % 1.),
+        color: Vec3::new(1.0, 0.7, 0.5),
     }) {
         vbo_data.push(vert);
     }
@@ -134,6 +134,16 @@ fn main() {
         FVec3::new(0.0, 1.0, 0.0),
         CoordinateOrientation::RightHanded,
     );
+    let indecies_a = [
+        0, 3, 1, 1, 3, 2, // triangles making up the top (+y) facing side.
+        4, 5, 7, 5, 6, 7, // bottom (-y)
+        8, 11, 9, 9, 11, 10, // right (+x)
+        12, 13, 15, 13, 14, 15, // left (-x)
+        16, 19, 17, 17, 19, 18, // back (+z)
+        20, 21, 23, 21, 22, 23, // forward (-z)
+    ];
+    let mut indecies = Vec::with_capacity_in(indecies_a.len(), ctru::linear::LinearAllocator);
+    indecies.extend_from_slice(&indecies_a);
 
     while apt.main_loop() {
         hid.scan_input();
@@ -159,18 +169,12 @@ fn main() {
                 unsafe {
                     instance.draw_elements(
                         buffer::Primitive::Triangles,
-                        DrawingIndices::U16(&[
-                            0, 3, 1, 1, 3, 2, // triangles making up the top (+y) facing side.
-                            4, 5, 7, 5, 6, 7, // bottom (-y)
-                            8, 11, 9, 9, 11, 10, // right (+x)
-                            12, 13, 15, 13, 14, 15, // left (-x)
-                            16, 19, 17, 17, 19, 18, // back (+z)
-                            20, 21, 23, 21, 22, 23, // forward (-z)
-                        ]),
+                        &buf_info,
+                        DrawingIndices::U16(&indecies),
                     );
                 }
 
-                instance.draw_arrays(buffer::Primitive::Triangles, vbo_data);
+                //instance.draw_arrays(buffer::Primitive::Triangles, vbo_data);
             };
 
             let Projections {
diff --git a/citro3d/src/lib.rs b/citro3d/src/lib.rs
index 133f369..88636ee 100644
--- a/citro3d/src/lib.rs
+++ b/citro3d/src/lib.rs
@@ -17,11 +17,13 @@ pub mod render;
 pub mod shader;
 pub mod texenv;
 pub mod uniform;
+mod util;
 
 use std::cell::OnceCell;
 use std::fmt;
 
 pub use error::{Error, Result};
+use util::is_linear_ptr;
 
 use self::texenv::TexEnv;
 use self::uniform::Uniform;
@@ -162,27 +164,40 @@ impl Instance {
     }
     /// Indexed drawing
     ///
+    /// Draws the vertices in `buf` indexed by `indices`. `indices` must be linearly allocated
+    ///
     /// # Safety
     /// If `indices` goes out of scope before the current frame ends it will cause a use-after-free (possibly by the GPU)
+    /// If `buf` does not contain all the vertices references by `indices` it will cause an invalid access by the GPU (this crashes citra)
+    ///
+    /// # Panics
+    /// If `indices` is not allocated in linear memory
     #[doc(alias = "C3D_DrawElements")]
     pub unsafe fn draw_elements<'a>(
         &mut self,
         primitive: buffer::Primitive,
+        buf: &buffer::Info,
         indices: impl Into<DrawingIndices<'a>>,
     ) {
+        self.set_buffer_info(buf);
         let indices: DrawingIndices<'a> = indices.into();
+        let elements = match indices {
+            DrawingIndices::U16(v) => v.as_ptr() as *const _,
+            DrawingIndices::U8(v) => v.as_ptr() as *const _,
+        };
+        assert!(
+            is_linear_ptr(elements),
+            "draw_elements requires linear allocated indices buffer"
+        );
         citro3d_sys::C3D_DrawElements(
             primitive as ctru_sys::GPU_Primitive_t,
             indices.len() as i32,
             // flag bit for short or byte
             match indices {
-                DrawingIndices::U16(_) => 1,
-                DrawingIndices::U8(_) => 0,
-            },
-            match indices {
-                DrawingIndices::U16(v) => v.as_ptr() as *const _,
-                DrawingIndices::U8(v) => v.as_ptr() as *const _,
-            },
+                DrawingIndices::U16(_) => citro3d_sys::C3D_UNSIGNED_SHORT,
+                DrawingIndices::U8(_) => citro3d_sys::C3D_UNSIGNED_BYTE,
+            } as i32,
+            elements,
         );
     }
 
diff --git a/citro3d/src/util.rs b/citro3d/src/util.rs
new file mode 100644
index 0000000..727e8a2
--- /dev/null
+++ b/citro3d/src/util.rs
@@ -0,0 +1,6 @@
+/// Check if pointer is in linear memory
+pub fn is_linear_ptr<P>(p: *const P) -> bool {
+    let addr = p as usize;
+    addr >= ctru_sys::OS_FCRAM_VADDR as usize
+        && addr < (ctru_sys::OS_FCRAM_VADDR as usize + ctru_sys::OS_FCRAM_SIZE as usize)
+}