add the sizeof() built-in function

Author: hlorenzi

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "customasm"
-version = "0.13.8"
+version = "0.13.9"
 edition = "2021"
 authors = ["hlorenzi <https://hlorenzi.com>"]
 description = "An assembler for custom, user-defined instruction sets!"

src/expr/builtin_fn.rs

@@ -8,6 +8,7 @@ pub fn resolve_builtin_fn(
     match name.as_ref()
     {
         "assert" => Some(eval_builtin_assert),
+        "sizeof" => Some(eval_builtin_sizeof),
         "le" => Some(eval_builtin_le),
         "ascii" => Some(eval_builtin_ascii),
         "utf8" => Some(eval_builtin_utf8),
@@ -30,6 +31,7 @@ pub fn get_static_size_builtin_fn(
     let get_static_size_fn = {
         match name.as_ref()
         {
+            "sizeof" => get_static_size_builtin_sizeof,
             "le" => get_static_size_builtin_le,
             _ => return None,
         }
@@ -49,6 +51,7 @@ pub fn get_statically_known_value_builtin_fn(
     match name.as_ref()
     {
         "assert" => false,
+        "sizeof" => true,
         "le" => true,
         "ascii" => true,
         "utf8" => true,
@@ -118,6 +121,20 @@ pub fn eval_builtin_assert(
 }
 
 
+pub fn eval_builtin_sizeof(
+    query: &mut expr::EvalFunctionQuery)
+    -> Result<expr::Value, ()>
+{
+    query.ensure_arg_number(1)?;
+
+    let (_bigint, size) = query.args[0].value.expect_sized_integerlike(
+        query.report,
+        query.args[0].span)?;
+    
+    Ok(expr::Value::make_integer(size))
+}
+
+
 pub fn eval_builtin_le(
     query: &mut expr::EvalFunctionQuery)
     -> Result<expr::Value, ()>
@@ -147,6 +164,22 @@ pub fn eval_builtin_le(
 }
 
 
+pub fn get_static_size_builtin_sizeof(
+    provider: &expr::StaticallyKnownProvider,
+    args: &Vec<expr::Expr>)
+    -> Option<usize>
+{
+    if args.len() == 1
+    {
+        args[0].get_static_size(provider)
+    }
+    else
+    {
+        None
+    }
+}
+
+
 pub fn get_static_size_builtin_le(
     provider: &expr::StaticallyKnownProvider,
     args: &Vec<expr::Expr>)

src/expr/expression.rs

@@ -269,6 +269,34 @@ impl Value
 	}
 
 
+	pub fn expect_sized_integerlike(
+		&self,
+		report: &mut diagn::Report,
+		span: diagn::Span)
+		-> Result<(util::BigInt, usize), ()>
+	{
+		if let Some(bigint) = self.coallesce_to_integer().get_bigint()
+		{
+			if let Some(size) = bigint.size
+			{
+				return Ok((bigint, size));
+			}
+
+			report.error_span(
+				"value has no definite size",
+				span);
+			
+			return Err(());
+		}
+
+		report.error_span(
+			"expected integer-like value with definite size",
+			span);
+
+		Err(())
+	}
+
+
 	pub fn expect_error_or_bigint(
 		self,
 		report: &mut diagn::Report,

tests/fn_builtin_sizeof/err_unsized.asm

@@ -0,0 +1 @@
+#d sizeof(123) ; error: failed / error: definite size

tests/fn_builtin_sizeof/ok_simple.asm

@@ -0,0 +1,19 @@
+#ruledef test
+{
+    ld {x} => {
+        (sizeof(x) > 8 ? 0xff : 0x00) @ x @ sizeof(x)`8
+    }
+}
+
+ld 0`0 ; = 0x00__00
+ld 0x0 ; = 0x00_0_04
+ld 0x00 ; = 0x00_00_08
+ld 0x12 ; = 0x00_12_08
+ld 0xff ; = 0x00_ff_08
+ld 0x100 ; = 0xff_100_0c
+ld 0x0100 ; = 0xff_0100_10
+ld 0x0000 ; = 0xff_0000_10
+ld 0xeeeee ; = 0xff_eeeee_14
+
+#d8 sizeof(0x1234) ; = 0x10
+#d8 sizeof("hello") ; = 0x28