From 2964bf9e23f772aa837175e50a624cf416cc0433 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Sun, 17 Nov 2019 00:58:09 +0300
Subject: [PATCH] inline assembly

---
 vlib/compiler/asm.v            | 38 ++++++++++++++++++++++++++++++++++
 vlib/compiler/parser.v         |  5 ++++-
 vlib/compiler/tests/asm_test.v | 14 +++++++++++++
 vlib/compiler/token.v          |  2 ++
 4 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 vlib/compiler/asm.v
 create mode 100644 vlib/compiler/tests/asm_test.v

diff --git a/vlib/compiler/asm.v b/vlib/compiler/asm.v
new file mode 100644
index 0000000000..dce43e817f
--- /dev/null
+++ b/vlib/compiler/asm.v
@@ -0,0 +1,38 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+module compiler
+
+fn (p mut Parser) inline_asm() {
+	if !p.inside_unsafe {
+		p.error('asm() needs to be run unside `unsafe {}`')
+	}	
+	p.next()
+	p.check(.lpar)
+	s := p.check_string()
+	p.genln('asm("$s"')
+	for p.tok == .str {
+		p.genln('"$p.lit"')
+		p.next()
+	}	
+	for p.tok == .colon {
+		p.next()
+		arg := p.check_string()
+		p.gen(': "$arg"')
+		if p.tok == .lpar {
+			p.next()
+			var_name := p.check_name()
+			if !p.known_var(var_name) {
+				p.error('unknown variable `$var_name`')
+			}	
+			p.check(.rpar)
+			p.genln('($var_name)')
+			
+		}	
+		
+	}	
+	p.genln(');')
+	p.check(.rpar)
+	
+}	
diff --git a/vlib/compiler/parser.v b/vlib/compiler/parser.v
index 87ba9f11d8..bd8563f8c3 100644
--- a/vlib/compiler/parser.v
+++ b/vlib/compiler/parser.v
@@ -1208,6 +1208,9 @@ fn (p mut Parser) statement(add_semi bool) string {
 	.key_assert {
 		p.assert_statement()
 	}
+	.key_asm {
+		p.inline_asm()
+	}	
 	else {
 		// An expression as a statement
 		typ := p.expression()
@@ -2745,7 +2748,7 @@ fn (p mut Parser) return_st() {
 	p.returns = true
 }
 
-fn (p Parser) get_deferred_text() string {
+fn (p &Parser) get_deferred_text() string {
 	// @emily33901: Scoped defer
 	// Check all of our defer texts to see if there is one at a higher scope level
 	// The one for our current scope would be the last so any before that need to be
diff --git a/vlib/compiler/tests/asm_test.v b/vlib/compiler/tests/asm_test.v
new file mode 100644
index 0000000000..3597aa0a0e
--- /dev/null
+++ b/vlib/compiler/tests/asm_test.v
@@ -0,0 +1,14 @@
+fn test_inline_asm() {
+	a := 10
+	b := 0
+	unsafe {
+		asm ("movl %1, %%eax;"
+      "movl %%eax, %0;"
+     :"=r"(b)
+     :"r"(a)
+     :"%eax"
+     )
+	}
+	assert a == 10
+	assert b == 10
+}
diff --git a/vlib/compiler/token.v b/vlib/compiler/token.v
index 77793bbce1..f285362837 100644
--- a/vlib/compiler/token.v
+++ b/vlib/compiler/token.v
@@ -80,6 +80,7 @@ enum TokenKind {
 	// keywords
 	keyword_beg
 	key_as
+	key_asm
 	key_assert
 	key_atomic
 	key_break
@@ -201,6 +202,7 @@ fn build_token_str() []string {
 	s[TokenKind.key_if] = 'if'
 	//s[TokenKind.key_it] = 'it'
 	s[TokenKind.key_else] = 'else'
+	s[TokenKind.key_asm] = 'asm'
 	s[TokenKind.key_return] = 'return'
 	s[TokenKind.key_module] = 'module'
 	s[TokenKind.key_sizeof] = 'sizeof'