Add string literals

1 files changed, 190 insertions, 21 deletions

diff --git a/boot/stage6.elna b/boot/stage6.elna
index f412cc6..7d426f9 100644
--- a/boot/stage6.elna
+++ b/boot/stage6.elna
@@ -1,9 +1,10 @@
-# ihis Source Code Form is subject to the terms of the Mozilla Public License,
+# This Source Code Form is subject to the terms of the Mozilla Public License,
 # 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/.
 
-# Stage6 compiler.
+# Stage 6 compiler.
 #
+# - String literals.
 
 .section .rodata
 
@@ -43,6 +44,9 @@ asm_type_directive: .string ".type "
 .type asm_type_function, @object
 asm_type_function: .string ", @function\n"
 
+.type asm_type_object, @object
+asm_type_object: .string ", @object\n"
+
 .type asm_colon, @object
 asm_colon: .string ":\n"
 
@@ -112,19 +116,110 @@ asm_comma: .string ", "
 .type asm_sp, @object
 asm_sp: .string "sp"
 
+.type asm_rodata, @object
+asm_rodata: .string ".section .rodata\n"
+
+.type asm_strings, @object
+asm_strings: .string "strings"
+
+.type asm_ascii, @object
+asm_ascii: .string " .ascii "
+
 .section .bss
 
 # When modifiying also change the read size in the entry point procedure.
 .type source_code, @object
 source_code: .zero 81920
 
+.type compiler_strings, @object
+compiler_strings: .zero 8192
+
 .section .data
 
+.type compiler_strings_position, @object
+compiler_strings_position: .word compiler_strings
+
+.type compiler_strings_length, @object
+compiler_strings_length: .word 0
+
 .type source_code_position, @object
 source_code_position: .word source_code
 
 .section .text
 
+# Calculates and returns the string token length between quotes, including the
+# escaping slash characters.
+#
+# Parameters:
+# a0 - String token pointer.
+#
+# Returns the length in a0.
+proc _string_length();
+begin
+	# Reset the counter.
+	v0 := 0;
+
+.string_length_loop:
+	v88 := v88 + 1;
+
+	lw t0, 88(sp)
+	lb t0, (t0)
+
+	li t1, '"'
+	beq t0, t1, .string_length_end
+
+	v0 := v0 + 1;
+	goto .string_length_loop;
+
+.string_length_end:
+	return v0
+end;
+
+# Adds a string to the global, read-only string storage.
+#
+# Parameters:
+# a0 - String token.
+#
+# Returns the offset from the beginning of the storage to the new string in a0.
+proc _add_string();
+begin
+	v0 := v88 + 1;
+	v4 := compiler_strings_length;
+
+.add_string_loop:
+	lw t0, 0(sp)
+	lb t1, (t0)
+	li t2, '"'
+
+	beq t1, t2, .add_string_end
+
+	la t2, compiler_strings_position
+	lw t3, (t2)
+	sb t1, (t3)
+
+	addi t3, t3, 1
+	sw t3, (t2)
+
+	addi t0, t0, 1
+	sw t0, 0(sp)
+
+	li t2, '\\'
+	bne t1, t2, .add_string_increment
+
+	goto .add_string_loop;
+
+.add_string_increment:
+	la t2, compiler_strings_length
+	lw t4, (t2)
+	addi t4, t4, 1
+	sw t4, (t2)
+
+	goto .add_string_loop;
+
+.add_string_end:
+	return v4
+end;
+
 # Reads standard input into a buffer.
 # a0 - Buffer pointer.
 # a1 - Buffer size.
@@ -595,6 +690,37 @@ begin
 
 end;
 
+proc _compile_string_literal();
+begin
+	_string_length(source_code_position);
+	sw a0, 0(sp)
+
+	_add_string(source_code_position);
+	sw a0, 4(sp)
+
+	_advance_token(v0 + 2);
+
+	_write_z(@asm_la);
+	_write_register('t', 0);
+	_write_z(@asm_comma);
+	_write_z(@asm_strings);
+	_write_c('\n');
+
+	_write_z(@asm_li);
+	_write_register('t', 1);
+	_write_z(@asm_comma);
+	_write_i(v4);
+	_write_c('\n');
+
+	_write_z(@asm_add);
+	_write_register('t', 0);
+	_write_z(@asm_comma);
+	_write_register('t', 0);
+	_write_z(@asm_comma);
+	_write_register('t', 1);
+	_write_c('\n');
+end;
+
 proc _compile_term();
 begin
 	la t0, source_code_position
@@ -614,6 +740,9 @@ begin
 	li t1, '~'
 	beq a0, t1, .compile_term_not
 
+	li t1, '"'
+	beq a0, t1, .compile_term_string_literal
+
 	_is_digit(v0);
 	bnez a0, .compile_term_integer_literal
 
@@ -639,6 +768,10 @@ begin
 	_compile_not_expression();
 	goto .compile_term_end;
 
+.compile_term_string_literal:
+	_compile_string_literal();
+	goto .compile_term_end;
+
 .compile_term_variable:
 	_compile_variable_expression();
 	goto .compile_term_end;
@@ -1336,63 +1469,99 @@ begin
 end;
 
 # Process the source code and print the generated code.
-proc _compile();
+proc _compile_module();
 begin
-.compile_loop:
+.compile_module_loop:
 	_skip_newlines();
 
 	la t0, source_code_position
 	lw t0, (t0)
 	lb t0, (t0)
-	beqz t0, .compile_end
+	beqz t0, .compile_module_end
 	li t1, '#'
-	beq t0, t1, .compile_comment
+	beq t0, t1, .compile_module_comment
 
 	# 8 is ".section" length.
 	_memcmp(source_code_position, @keyword_section, 8);
-	beqz a0, .compile_section
+	beqz a0, .compile_module_section
 
 	# 5 is ".type" length.
 	_memcmp(source_code_position, @keyword_type, 5);
-	beqz a0, .compile_type
+	beqz a0, .compile_module_type
 
 	# 5 is "proc " length. Space is needed to distinguish from "procedure".
 	_memcmp(source_code_position, @keyword_proc, 5);
-	beqz a0, .compile_procedure
+	beqz a0, .compile_module_procedure
 
 	# 6 is ".globl" length.
 	_memcmp(source_code_position, @keyword_global, 6);
-	beqz a0, .compile_global
+	beqz a0, .compile_module_global
 
 	# Not a known token, exit.
-	goto .compile_end;
+	goto .compile_module_end;
 
-.compile_section:
+.compile_module_section:
 	_compile_section();
 
-	goto .compile_loop;
+	goto .compile_module_loop;
 
-.compile_type:
+.compile_module_type:
 	_compile_type();
 
-	goto .compile_loop;
+	goto .compile_module_loop;
 
-.compile_global:
+.compile_module_global:
 	_compile_line();
 
-	goto .compile_loop;
+	goto .compile_module_loop;
 
-.compile_comment:
+.compile_module_comment:
 	_skip_comment();
 
-	goto .compile_loop;
+	goto .compile_module_loop;
 
-.compile_procedure:
+.compile_module_procedure:
 	_compile_procedure();
 
-	goto .compile_loop;
+	goto .compile_module_loop;
+
+.compile_module_end:
+end;
+
+proc _compile();
+begin
+	_compile_module();
+
+	_write_z(@asm_rodata);
+	_write_z(@asm_type_directive);
+	_write_z(@asm_strings);
+	_write_z(@asm_type_object);
+	_write_z(@asm_strings);
+	_write_c(':');
+	_write_z(@asm_ascii);
+	_write_c('"');
+
+	la t0, compiler_strings
+	sw t0, 0(sp)
+
+.compile_loop:
+	lw t0, 0(sp)
+	la t1, compiler_strings_position
+	lw t1, (t1)
+	bge t0, t1, .compile_end
+
+	lb a0, (t0)
+
+	addi t0, t0, 1
+	sw t0, 0(sp)
+
+	_write_c();
+
+	j .compile_loop
 
 .compile_end:
+	_write_c('"');
+	_write_c('\n');
 end;
 
 # Terminates the program. a0 contains the return code.