wasm_module: Create DataSection::load_into

crates/wasm_interp/src/execute.rs

@@ -1,5 +1,6 @@
 use bumpalo::{collections::Vec, Bump};
 use std::fmt::Write;
+use std::iter;
 
 use roc_wasm_module::opcodes::OpCode;
 use roc_wasm_module::parse::Parse;
@@ -59,6 +60,8 @@ impl<'a> ExecutionState<'a> {
                 e.offset, e.message
             )
         })?;
+        let mut memory = Vec::from_iter_in(iter::repeat(0).take(mem_bytes as usize), arena);
+        module.data.load_into(&mut memory)?;
 
         let globals = module.global.initial_values(arena);
 
@@ -110,7 +113,7 @@ impl<'a> ExecutionState<'a> {
         };
 
         Ok(ExecutionState {
-            memory: Vec::with_capacity_in(mem_bytes as usize, arena),
+            memory,
             call_stack,
             value_stack,
             globals,

crates/wasm_module/src/sections.rs

@@ -1,4 +1,5 @@
 use std::fmt::{Debug, Formatter};
+use std::io::Write;
 
 use bumpalo::collections::vec::Vec;
 use bumpalo::Bump;
@@ -1490,6 +1491,29 @@ impl<'a> DataSection<'a> {
         segment.serialize(&mut self.bytes);
         index
     }
+
+    pub fn load_into(&self, memory: &mut [u8]) -> Result<(), String> {
+        let mut cursor = 0;
+        for _ in 0..self.count {
+            let mode =
+                DataMode::parse((), &self.bytes, &mut cursor).map_err(|e| format!("{:?}", e))?;
+            let start = match mode {
+                DataMode::Active {
+                    offset: ConstExpr::I32(addr),
+                } => addr as usize,
+                _ => {
+                    continue;
+                }
+            };
+            let len32 = u32::parse((), &self.bytes, &mut cursor).map_err(|e| format!("{:?}", e))?;
+            let len = len32 as usize;
+            let mut target_slice = &mut memory[start..][..len];
+            target_slice
+                .write(&self.bytes[cursor..][..len])
+                .map_err(|e| format!("{:?}", e))?;
+        }
+        Ok(())
+    }
 }
 
 impl<'a> Parse<&'a Bump> for DataSection<'a> {