Implement string literals

1 files changed, 43 insertions, 9 deletions

diff --git a/boot/stage5.elna b/boot/stage5.elna
index 3aed6c3..88b407f 100644
--- a/boot/stage5.elna
+++ b/boot/stage5.elna
@@ -2,7 +2,7 @@
 # v. 2.0. If a copy of the MPL was not distributed with this file, You can
 # obtain one at https://mozilla.org/MPL/2.0/.
 
-# Stage4 compiler.
+# Stage5 compiler.
 #
 # - Stack size increased to 128 bytes per procedure.
 #   7 words on the stack, 92 - 120, are reversed for procedure arguments (caller side).
@@ -13,6 +13,7 @@
 # - Binary addition "+" and multiplication "*".
 # - Binary logical operations: & (and), or and xor.
 # - Binary comparison operations: =, <, <=, >, >=, <>.
+# - Return statement.
 
 .section .rodata
 
@@ -23,7 +24,7 @@ keyword_section: .ascii ".section"
 keyword_type: .ascii ".type"
 
 .type keyword_ret, @object
-keyword_ret: .ascii "ret"
+keyword_ret: .ascii "\tret"
 
 .type keyword_global, @object
 keyword_global: .ascii ".globl"
@@ -97,6 +98,9 @@ asm_or: .string "\tor "
 .type asm_xor, @object
 asm_xor: .string "\txor "
 
+.type asm_xori, @object
+asm_xori: .string "\txori "
+
 .type asm_sub, @object
 asm_sub: .string "\tsub "
 
@@ -109,6 +113,9 @@ asm_snez: .string "\tsnez "
 .type asm_slt, @object
 asm_slt: .string "\tslt "
 
+.type asm_mv, @object
+asm_mv: .string "\tmv "
+
 .type asm_comma, @object
 asm_comma: .string ", "
 
@@ -889,16 +896,18 @@ begin
 	_write_z(@asm_slt);
 	_write_register('t', 0);
 	_write_z(@asm_comma);
-	_write_register('t', 1);
-	_write_z(@asm_comma);
 	_write_register('t', 0);
+	_write_z(@asm_comma);
+	_write_register('t', 1);
 	_write_c('\n');
 
 	# Execute the operation.
-	_write_z(@asm_not);
+	_write_z(@asm_xori);
 	_write_register('t', 0);
 	_write_z(@asm_comma);
 	_write_register('t', 0);
+	_write_z(@asm_comma);
+	_write_i(1);
 	_write_c('\n');
 
 	goto .compile_expression_end;
@@ -933,16 +942,18 @@ begin
 	_write_z(@asm_slt);
 	_write_register('t', 0);
 	_write_z(@asm_comma);
-	_write_register('t', 0);
-	_write_z(@asm_comma);
 	_write_register('t', 1);
+	_write_z(@asm_comma);
+	_write_register('t', 0);
 	_write_c('\n');
 
 	# Execute the operation.
-	_write_z(@asm_not);
+	_write_z(@asm_xori);
 	_write_register('t', 0);
 	_write_z(@asm_comma);
 	_write_register('t', 0);
+	_write_z(@asm_comma);
+	_write_i(1);
 	_write_c('\n');
 
 	goto .compile_expression_end;
@@ -1167,6 +1178,19 @@ begin
 	_write_c(')');
 end;
 
+proc _compile_return_statement();
+begin
+	# Skip "return" keyword and whitespace after it.
+	_advance_token(7);
+	_compile_expression();
+
+	_write_z(@asm_mv);
+	_write_register('a', 0);
+	_write_z(@asm_comma);
+	_write_register('t', 0);
+
+end;
+
 proc _compile_statement();
 begin
 	# This is a call if the statement starts with an underscore.
@@ -1185,6 +1209,10 @@ begin
 	li t1, 'v'
 	beq t0, t1, .compile_statement_assignment
 
+	# keyword_ret contains "\tret", so it's 4 bytes long.
+	_memcmp(source_code_position, @keyword_ret, 4);
+	beqz a0, .compile_statement_return
+
 	_compile_line();
 	goto .compile_statement_end;
 
@@ -1206,9 +1234,15 @@ begin
 
 	goto .compile_statement_semicolon;
 
+.compile_statement_return:
+	_advance_token(1);
+	_compile_return_statement();
+	_write_c('\n');
+
+	goto .compile_statement_end;
+
 .compile_statement_semicolon:
 	_advance_token(2);
-
 	_write_c('\n');
 
 .compile_statement_end: