1 files changed, 162 insertions, 0 deletions
diff --git a/third_party/rust/spirv-cross-internal/src/emscripten.rs b/third_party/rust/spirv-cross-internal/src/emscripten.rs
new file mode 100644
index 0000000000..f134fbd88c
--- /dev/null
+++ b/third_party/rust/spirv-cross-internal/src/emscripten.rs
@@ -0,0 +1,162 @@
+//! Utilities for interacting with the generated Emscripten module.
+//! Most functionality is generalized, but some functionality is specific to SPIRV-Cross.
+
+use crate::{bindings, ErrorCode};
+use js_sys::{global, Object, Reflect, Uint32Array, Uint8Array};
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen]
+extern "C" {
+    // Raw Emscripten bindings
+    #[wasm_bindgen(js_namespace = sc_internal)]
+    fn _malloc(size: u32) -> u32;
+
+    #[wasm_bindgen(js_namespace = sc_internal)]
+    fn _free(offset: u32);
+}
+
+pub fn get_module() -> Module {
+    const MODULE_NAME: &'static str = "sc_internal";
+    let module = Reflect::get(&global(), &JsValue::from_str(MODULE_NAME))
+        .unwrap()
+        .into();
+    Module { module }
+}
+
+const U32_SIZE: u32 = std::mem::size_of::<u32>() as u32;
+
+fn get_value<T>(object: &Object, key: &str) -> T
+where
+    T: std::convert::From<wasm_bindgen::JsValue>,
+{
+    Reflect::get(object, &JsValue::from_str(key))
+        .unwrap()
+        .into()
+}
+
+/// An Emscripten pointer.
+/// Internally stores an offset to a location on the Emscripten `u8` heap.
+#[derive(Clone, Copy)]
+pub struct Pointer {
+    offset: u32,
+}
+
+impl Pointer {
+    pub fn from_offset(offset: u32) -> Self {
+        Pointer { offset }
+    }
+
+    pub fn as_offset(&self) -> u32 {
+        self.offset
+    }
+}
+
+pub struct Module {
+    module: Object,
+}
+
+impl Module {
+    /// Allocate memory on the heap.
+    pub unsafe fn allocate(&self, byte_len: u32) -> Pointer {
+        Pointer {
+            offset: _malloc(byte_len),
+        }
+    }
+
+    pub unsafe fn free(&self, pointer: Pointer) {
+        _free(pointer.as_offset())
+    }
+
+    // Read a `u32` value from the heap.
+    pub unsafe fn get_u32(&self, pointer: Pointer) -> u32 {
+        let offset = &JsValue::from_f64((pointer.offset / U32_SIZE) as f64);
+        // TODO: Remove Reflect
+        Reflect::get(&self.heap_u32(), offset)
+            .unwrap()
+            .as_f64()
+            .unwrap() as u32
+    }
+
+    /// Set memory on the heap to `bytes`.
+    pub unsafe fn set_from_u8_typed_array(&self, pointer: Pointer, bytes: Uint8Array) {
+        let buffer: JsValue = self.heap_u8().buffer().into();
+        let memory =
+            Uint8Array::new_with_byte_offset_and_length(&buffer, pointer.offset, bytes.length());
+        memory.set(&bytes, 0);
+    }
+
+    /// Set memory on the heap to `bytes`.
+    pub unsafe fn set_from_u8_slice(&self, pointer: Pointer, bytes: &[u8]) {
+        self.set_from_u8_typed_array(pointer, Uint8Array::view(bytes));
+    }
+
+    fn heap_u8(&self) -> Uint8Array {
+        const HEAP_U8: &'static str = "HEAPU8";
+        get_value(&self.module, HEAP_U8)
+    }
+
+    fn heap_u32(&self) -> Uint32Array {
+        const HEAP_U32: &'static str = "HEAPU32";
+        get_value(&self.module, HEAP_U32)
+    }
+
+    /// Clones all bytes from the heap into a `Vec<u8>` while `should_continue` returns `true`.
+    /// Optionally include the last byte (i.e. to support peeking the final byte for nul-terminated strings).
+    pub unsafe fn read_bytes_into_vec_while<F>(
+        &self,
+        pointer: Pointer,
+        should_continue: F,
+        include_last_byte: bool,
+    ) -> Vec<u8>
+    where
+        F: Fn(u8, usize) -> bool,
+    {
+        let mut bytes = Vec::new();
+        let heap = &self.heap_u8();
+        let start_offset = pointer.offset as usize;
+        loop {
+            let bytes_read = bytes.len();
+            let offset = &JsValue::from_f64((start_offset + bytes_read) as f64);
+            let byte = Reflect::get(heap, offset).unwrap().as_f64().unwrap() as u8;
+            if should_continue(byte, bytes_read) {
+                bytes.push(byte);
+                continue;
+            }
+            if include_last_byte {
+                bytes.push(byte);
+            }
+            break;
+        }
+        bytes
+    }
+
+    /// Clones all bytes from the heap into the pointer provided while `should_continue` returns `true`.
+    /// Optionally include the last byte (i.e. to support peeking the final byte for nul-terminated strings).
+    /// Assumes the memory at the pointer is large enough to hold all bytes read (based on when `should_continue` terminates).
+    pub unsafe fn read_bytes_into_pointer_while<F>(
+        &self,
+        pointer: Pointer,
+        should_continue: F,
+        include_last_byte: bool,
+        into_pointer: *mut u8,
+    ) where
+        F: Fn(u8, usize) -> bool,
+    {
+        let heap = &self.heap_u8();
+        let start_offset = pointer.offset as usize;
+        let mut bytes_read = 0;
+        loop {
+            let offset = &JsValue::from_f64((start_offset + bytes_read) as f64);
+            let byte = Reflect::get(heap, offset).unwrap().as_f64().unwrap() as u8;
+            if should_continue(byte, bytes_read) {
+                *into_pointer.offset(bytes_read as isize) = byte;
+                bytes_read += 1;
+                continue;
+            }
+            if include_last_byte {
+                *into_pointer.offset(bytes_read as isize) = byte;
+            }
+            break;
+        }
+    }
+}