Allow BufferField -> Integer conversion

src/aml/mod.rs

@@ -807,17 +807,19 @@ where
                     }
                     Opcode::DerefOf => {
                         let [Argument::Object(object)] = &op.arguments[..] else { panic!() };
-                        let result = if object.typ() == ObjectType::Reference {
-                            object.clone().unwrap_reference()
-                        } else if object.typ() == ObjectType::String {
-                            let path = AmlName::from_str(&object.as_string().unwrap())?;
-                            let (_, object) = self.namespace.lock().search(&path, &context.current_scope)?;
-                            object.clone()
-                        } else {
-                            return Err(AmlError::ObjectNotOfExpectedType {
-                                expected: ObjectType::Reference,
-                                got: object.typ(),
-                            });
+                        let result = match **object {
+                            Object::Reference { kind: _, inner: _ } => object.clone().unwrap_reference(),
+                            Object::String(_) => {
+                                let path = AmlName::from_str(&object.as_string().unwrap())?;
+                                let (_, object) = self.namespace.lock().search(&path, &context.current_scope)?;
+                                object.clone()
+                            }
+                            _ => {
+                                return Err(AmlError::ObjectNotOfExpectedType {
+                                    expected: ObjectType::Reference,
+                                    got: object.typ(),
+                                });
+                            }
                         };
                         context.contribute_arg(Argument::Object(result));
                         context.retire_op(op);
@@ -1796,8 +1798,9 @@ where
         let [Argument::Object(left), Argument::Object(right), target] = &op.arguments[0..3] else { panic!() };
         let target2 = if op.op == Opcode::Divide { Some(&op.arguments[3]) } else { None };
 
-        let left = left.clone().unwrap_transparent_reference().as_integer()?;
-        let right = right.clone().unwrap_transparent_reference().as_integer()?;
+        let allowed_length = if self.dsdt_revision >= 2 { 8 } else { 4 };
+        let left = left.clone().unwrap_transparent_reference().to_integer(allowed_length)?;
+        let right = right.clone().unwrap_transparent_reference().to_integer(allowed_length)?;
 
         let result = match op.op {
             Opcode::Add => left.wrapping_add(right),
@@ -1981,43 +1984,7 @@ where
         let [Argument::Object(operand), target] = &op.arguments[..] else { panic!() };
         let operand = operand.clone().unwrap_transparent_reference();
 
-        let result = match *operand {
-            Object::Integer(value) => Object::Integer(value),
-            Object::Buffer(ref bytes) => {
-                /*
-                 * The spec says this should respect the revision of the current definition block.
-                 * Apparently, the NT interpreter always uses the first 8 bytes of the buffer.
-                 */
-                let mut to_interpret = [0u8; 8];
-                (to_interpret[0..usize::min(bytes.len(), 8)]).copy_from_slice(bytes);
-                Object::Integer(u64::from_le_bytes(to_interpret))
-            }
-            Object::String(ref value) => {
-                /*
-                 * This is about the same level of effort as ACPICA puts in. The uACPI test suite
-                 * has tests that this fails - namely because of support for octal, signs, strings
-                 * that won't fit in a `u64` etc. We probably need to write a more robust parser
-                 * 'real' parser to handle those cases.
-                 */
-                let value = value.trim();
-                let value = value.to_ascii_lowercase();
-                let (value, radix): (&str, u32) = match value.strip_prefix("0x") {
-                    Some(value) => {
-                        (value.split(|c: char| !c.is_ascii_hexdigit()).next().unwrap_or(""), 16)
-                    }
-                    None => (value.split(|c: char| !c.is_ascii_digit()).next().unwrap_or(""), 10),
-                };
-                match value.len() {
-                    0 => Object::Integer(0),
-                    _ => Object::Integer(u64::from_str_radix(value, radix).map_err(|_| {
-                        AmlError::InvalidOperationOnObject { op: Operation::ToInteger, typ: ObjectType::String }
-                    })?),
-                }
-            }
-            _ => Err(AmlError::InvalidOperationOnObject { op: Operation::ToBuffer, typ: operand.typ() })?,
-        }
-        .wrap();
-
+        let result = Object::Integer(operand.to_integer(if self.dsdt_revision >= 2 { 8 } else { 4 })?).wrap();
         let result = self.do_store(target, result)?;
         context.contribute_arg(Argument::Object(result));
         context.retire_op(op);
@@ -3419,4 +3386,7 @@ pub enum AmlError {
     /// This variant is set by the host, not by the library, and can be used when it is convenient
     /// not to construct a more complex error type around [`AmlError`].
     HostError(String),
+
+    /// An integer operation was attempted for an integer greater than 8 bytes long.
+    InvalidIntegerSize(usize),
 }

src/aml/object.rs

@@ -177,6 +177,9 @@ impl Object {
         WrappedObject::new(self)
     }
 
+    /// Unwraps an integer object. Errors if not already an integer.
+    ///
+    /// For casting to integer, use [`Object::to_integer`] instead.
     pub fn as_integer(&self) -> Result<u64, AmlError> {
         if let Object::Integer(value) = self {
             Ok(*value)
@@ -201,18 +204,57 @@ impl Object {
         }
     }
 
+    /// Converts the object to an integer. Used for both implicit and explicit conversions.
+    ///
+    /// To avoid the cast, use [`Object::as_integer`] instead.
     pub fn to_integer(&self, allowed_bytes: usize) -> Result<u64, AmlError> {
+        // This check shouldn't hit, but it protects the `to_interpret` buffer below from panicking.
+        if allowed_bytes > size_of::<u64>() {
+            return Err(AmlError::InvalidIntegerSize(allowed_bytes));
+        }
+
         match self {
             Object::Integer(value) => Ok(*value),
-            Object::Buffer(value) => {
-                let length = usize::min(value.len(), allowed_bytes);
-                let mut bytes = [0u8; 8];
-                bytes[0..length].copy_from_slice(&value[0..length]);
-                Ok(u64::from_le_bytes(bytes))
+            Object::Buffer(bytes) => {
+                /*
+                 * The spec says this should respect the revision of the current definition block.
+                 * Apparently, the NT interpreter always uses the first 8 bytes of the buffer.
+                 */
+                let length = usize::min(bytes.len(), allowed_bytes);
+                let mut to_interpret = [0u8; 8];
+                to_interpret[0..length].copy_from_slice(&bytes[0..length]);
+                Ok(u64::from_le_bytes(to_interpret))
+            }
+            Object::String(value) => {
+                /*
+                 * This is about the same level of effort as ACPICA puts in. The uACPI test suite
+                 * has tests that this fails - namely because of support for octal, signs, strings
+                 * that won't fit in a `u64` etc. We probably need to write a more robust parser
+                 * 'real' parser to handle those cases.
+                 */
+                let value = value.trim();
+                let value = value.to_ascii_lowercase();
+                let (value, radix): (&str, u32) = match value.strip_prefix("0x") {
+                    Some(value) => (value.split(|c: char| !c.is_ascii_hexdigit()).next().unwrap_or(""), 16),
+                    None => (value.split(|c: char| !c.is_ascii_digit()).next().unwrap_or(""), 10),
+                };
+                match value.len() {
+                    0 => Ok(0),
+                    _ => Ok(u64::from_str_radix(value, radix).map_err(|_| {
+                        AmlError::InvalidOperationOnObject { op: Operation::ToInteger, typ: ObjectType::String }
+                    })?),
+                }
             }
-            // TODO: how should we handle invalid inputs? What does NT do here?
-            Object::String(value) => Ok(value.parse::<u64>().unwrap_or(0)),
-            _ => Ok(0),
+            Object::BufferField { .. } => {
+                let mut buffer = [0u8; 8];
+                self.read_buffer_field(&mut buffer)?;
+                let mut result = u64::from_le_bytes(buffer);
+                if allowed_bytes < 8 {
+                    result &= (1 << (allowed_bytes as u64 * 8)) - 1;
+                }
+                Ok(result)
+            }
+            _ => Err(AmlError::InvalidOperationOnObject { op: Operation::ToInteger, typ: self.typ() })?,
         }
     }
 
@@ -511,4 +553,51 @@ mod tests {
         copy_bits(&src, 0, &mut dst, 2, 15);
         assert_eq!(dst, [0b1111_1101, 0b1101_1110, 0b0000_0001, 0b0000_0000, 0b0000_0000]);
     }
+
+    #[test]
+    fn buffer_to_integer() {
+        let buffer = Object::Buffer(Vec::from([0xab, 0xcd, 0xef, 0x01, 0xff]));
+        assert_eq!(buffer.to_integer(4).unwrap(), 0x01efcdab);
+    }
+
+
+    #[test]
+    fn buffer_field_to_integer() {
+        const BUFFER: [u8; 5] = [0xffu8; 5];
+        let buffer = Object::Buffer(Vec::from(BUFFER)).wrap();
+        let buffer_field = Object::BufferField {
+            buffer,
+            offset: 5,
+            length: 9,
+        };
+
+        assert_eq!(buffer_field.to_integer(4).unwrap(), 0x1ff);
+    }
+
+    #[test]
+    fn buffer_field_to_4_byte_integer() {
+        // The ones in this buffer are strategically chosen to not make it to the final integer.
+        const BUFFER: [u8; 5] = [0x0f, 0x00, 0x00, 0x00, 0xf0];
+        let buffer = Object::Buffer(Vec::from(BUFFER)).wrap();
+        let buffer_field = Object::BufferField {
+            buffer,
+            offset: 4,
+            length: 36, // This should be truncated to 32 bits in the conversion
+        };
+
+        assert_eq!(buffer_field.to_integer(4).unwrap(), 0);
+    }
+
+    #[test]
+    fn buffer_field_to_8_byte_integer() {
+        const BUFFER: [u8; 6] = [0x0f, 0x00, 0x00, 0x00, 0xf0, 0xff];
+        let buffer = Object::Buffer(Vec::from(BUFFER)).wrap();
+        let buffer_field = Object::BufferField {
+            buffer,
+            offset: 4,
+            length: 36,
+        };
+
+        assert_eq!(buffer_field.to_integer(8).unwrap(), 0x0000000f_00000000);
+    }
 }

src/aml/resource.rs

@@ -551,7 +551,6 @@ fn extended_interrupt_descriptor(bytes: &[u8]) -> Result<Resource, AmlError> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use alloc::sync::Arc;
 
     #[test]
     fn test_parses_keyboard_crs() {

tests/de_ref_of.rs

@@ -0,0 +1,27 @@
+use aml_test_tools::handlers::null_handler::NullHandler;
+
+mod test_infra;
+
+#[test]
+fn test_deref_of_buffer_field() {
+    const AML: &str = r#"
+DefinitionBlock ("", "SSDT", 2, "RSACPI", "DerefOf", 0x00000002) {
+    Scope (\_SB) {
+        Name (ADAT, Buffer (0x0010) {
+            /* 0000 */  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            /* 0008 */  0x00, 0xaa, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        })
+    }
+
+    Method(MAIN, 0, NotSerialized) {
+        Local0 = (DerefOf(\_SB.ADAT[0x09]))
+        // This relies on subtraction rather than equality as logical ops on BufferFields don't work
+        // yet.
+        return (Local0 - 0xaa)
+    }
+}
+"#;
+
+    let handler = NullHandler {};
+    test_infra::run_aml_test(AML, handler);
+}