Implement arithmetic negation

Rakefile

@@ -6,7 +6,6 @@
 require 'open3'
 require 'rake/clean'
 
-CROSS_GCC = '../eugenios/build/rootfs/bin/riscv32-unknown-linux-gnu-gcc'
 SYSROOT = '../eugenios/build/sysroot'
 QEMU = 'qemu-riscv32'
 STAGES = Dir.glob('boot/stage*.elna').collect { |stage| File.basename stage, '.elna' }.sort
@@ -16,6 +15,10 @@ CLEAN.include 'build/boot', 'build/valid'
 directory 'build/boot'
 directory 'build/valid'
 
+def compile(input, output)
+  sh ENV.fetch('CC', 'gcc'), '-nostdlib', '-o', output, input
+end
+
 task default: :boot
 
 desc 'Final stage'
@@ -47,7 +50,7 @@ end
 rule /^build\/[[:alpha:]]+\/stage[[:digit:]]+$/ => ->(match) {
   "#{match}.s"
 } do |t|
-  sh CROSS_GCC, '-nostdlib', '-o', t.name, *t.prerequisites
+  compile(*t.prerequisites, t.name)
 end
 
 STAGES.each do |stage|
@@ -91,5 +94,5 @@ end
 file 'build/boot/stage1' => ['build/boot', 'boot/stage1.s'] do |t|
   source = t.prerequisites.select { |prerequisite| prerequisite.end_with? '.s' }
 
-  sh CROSS_GCC, '-nostdlib', '-o', t.name, *source
+  compile(*source, t.name)
 end

boot/stage5.elna

@@ -4,11 +4,11 @@
 
 # Stage4 compiler.
 #
-# - Taking value of local and global variables. Variables that doesn't begin
+# - Stack size increased to 128 bytes per procedure.
-#   with "v" are considered global.
+#   7 words on the stack, 92 - 120, are reversed for procedure arguments (caller side).
-# - Simple variable assignment, e.g. v0 := 5 or v0 := global_variable;
+#   7 words on the stack, 64 - 92, are reserved for procedure parameters (callee side).
-#   7 words on the stack, 28 - 56, are reversed for procedure arguments (caller side).
+#   The first parameter is in 88, the second in 84 and so forth.
-# - Take address unary operation "@".
+# - Unary negate operation, e.g. -5.
 
 .section .rodata
 
@@ -37,10 +37,10 @@ keyword_begin: .ascii "begin"
 keyword_var: .ascii "var"
 
 .type asm_prologue, @object
-asm_prologue: .string "\taddi sp, sp, -64\n\tsw ra, 60(sp)\n\tsw s0, 56(sp)\n\taddi s0, sp, 64\n"
+asm_prologue: .string "\taddi sp, sp, -128\n\tsw ra, 124(sp)\n\tsw s0, 120(sp)\n\taddi s0, sp, 128\n"
 
 .type asm_epilogue, @object
-asm_epilogue: .string "\tlw ra, 60(sp)\n\tlw s0, 56(sp)\n\taddi sp, sp, 64\n\tret\n"
+asm_epilogue: .string "\tlw ra, 124(sp)\n\tlw s0, 120(sp)\n\taddi sp, sp, 128\n\tret\n"
 
 .type asm_type_directive, @object
 asm_type_directive: .string ".type "
@@ -72,11 +72,8 @@ asm_sw: .string "\tsw "
 .type asm_addi, @object
 asm_addi: .string "\taddi "
 
-.type asm_t0, @object
+.type asm_neg, @object
-asm_t0: .string "t0"
+asm_neg: .string "\tneg "
-
-.type asm_t1, @object
-asm_t1: .string "t1"
 
 .type asm_comma, @object
 asm_comma: .string ", "
@@ -486,7 +483,7 @@ end;
 proc _compile_integer_literal();
 begin
 	_write_z(@asm_li);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_read_token();
@@ -499,7 +496,7 @@ end;
 proc _compile_character_literal();
 begin
 	_write_z(@asm_li);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_write_c('\'');
@@ -532,11 +529,11 @@ begin
 	_compile_designator();
 
 	_write_z(@asm_lw);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_write_c('(');
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 
 	_write_c(')');
 	_write_c('\n');
@@ -551,7 +548,23 @@ begin
 
 end;
 
-proc _compile_expression();
+proc _compile_negate_expression();
+begin
+	# Skip the "-" sign.
+	_advance_token(1);
+	_compile_term();
+
+	_write_z(@asm_neg);
+	_write_register('t', 0);
+
+	_write_z(@asm_comma);
+	_write_register('t', 0);
+
+	_write_c('\n');
+
+end;
+
+proc _compile_term();
 begin
 	la t0, source_code_position
 	lw t0, (t0)
@@ -559,33 +572,45 @@ begin
 	sw a0, 0(sp)
 
 	li t1, '\''
-	beq a0, t1, .compile_expression_character_literal
+	beq a0, t1, .compile_term_character_literal
 
 	li t1, '@'
-	beq a0, t1, .compile_expression_address
+	beq a0, t1, .compile_term_address
+
+	li t1, '-'
+	beq a0, t1, .compile_term_negation
 
 	_is_digit(v0);
-	bnez a0, .compile_expression_integer_literal
+	bnez a0, .compile_term_integer_literal
 
-	goto .compile_expression_variable;
+	goto .compile_term_variable;
 
-.compile_expression_character_literal:
+.compile_term_character_literal:
 	_compile_character_literal();
-	goto .compile_expression_end;
+	goto .compile_term_end;
 
-.compile_expression_integer_literal:
+.compile_term_integer_literal:
 	_compile_integer_literal();
-	goto .compile_expression_end;
+	goto .compile_term_end;
 
-.compile_expression_address:
+.compile_term_address:
 	_compile_address_expression();
-	goto .compile_expression_end;
+	goto .compile_term_end;
 
-.compile_expression_variable:
+.compile_term_negation:
+	_compile_negate_expression();
+	goto .compile_term_end;
+
+.compile_term_variable:
 	_compile_variable_expression();
-	goto .compile_expression_end;
+	goto .compile_term_end;
 
-.compile_expression_end:
+.compile_term_end:
+end;
+
+proc _compile_expression();
+begin
+	_compile_term();
 end;
 
 proc _compile_call();
@@ -617,14 +642,14 @@ begin
 
 	# Save the argument on the stack.
 	_write_z(@asm_sw);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
-	# Calculate the stack offset: 52 - (4 * argument_counter)
+	# Calculate the stack offset: 116 - (4 * argument_counter)
 	lw t0, 8(sp)
 	li t1, 4
 	mul t0, t0, t1
-	li t1, 52
+	li t1, 116
 	sub a0, t1, t0
 	_write_i();
 
@@ -668,11 +693,11 @@ begin
 
 	_write_z(@asm_comma);
 
-	# Calculate the stack offset: 52 - (4 * argument_counter)
+	# Calculate the stack offset: 116 - (4 * argument_counter)
 	lw t0, 8(sp)
 	li t1, 4
 	mul t0, t0, t1
-	li t1, 52
+	li t1, 116
 	sub a0, t1, t0
 	_write_i();
 
@@ -712,7 +737,7 @@ begin
 	_advance_token(1);
 
 	_write_z(@asm_addi);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 	_write_z(@asm_sp);
 	_write_z(@asm_comma);
@@ -733,7 +758,7 @@ end;
 proc _compile_global_designator();
 begin
 	_write_z(@asm_la);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_read_token();
@@ -772,7 +797,7 @@ begin
 
 	# Save the assignee address on the stack.
 	_write_z(@asm_sw);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_write_i(20);
@@ -787,7 +812,7 @@ begin
 	_compile_expression();
 
 	_write_z(@asm_lw);
-	_write_z(@asm_t1);
+	_write_register('t', 1);
 	_write_z(@asm_comma);
 
 	_write_i(20);
@@ -797,11 +822,11 @@ begin
 	_write_c('\n');
 
 	_write_z(@asm_sw);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_write_c('(');
-	_write_z(@asm_t1);
+	_write_register('t', 1);
 	_write_c(')');
 end;
 
@@ -855,11 +880,8 @@ end;
 proc _compile_procedure_body();
 begin
 .compile_procedure_body_loop:
-	la a0, source_code_position
+	# 3 is "end" length.
-	lw a0, (a0)
+	_memcmp(source_code_position, @keyword_end, 3);
-	la a1, keyword_end
-	li a2, 3 # "end" length.
-	_memcmp();
 
 	beqz a0, .compile_procedure_body_epilogue
 
@@ -869,6 +891,60 @@ begin
 .compile_procedure_body_epilogue:
 end;
 
+# Writes a regster name to the standard output.
+#
+# Parameters:
+# a0 - Register character.
+# a1 - Register number.
+proc _write_register();
+begin
+	sw a0, 0(sp)
+	sw a1, 4(sp)
+
+	_write_c();
+
+	lw a0, 4(sp)
+	li t0, '0'
+	add a0, a0, t0
+	_write_c();
+end;
+
+proc _compile_procedure_prologue();
+begin
+	_write_z(@asm_prologue);
+
+	v0 := 0;
+
+.compile_procedure_prologue_loop:
+	_write_z(@asm_sw);
+
+	li a0, 'a'
+	lw a1, 0(sp)
+	_write_register();
+
+	_write_z(@asm_comma);
+
+	# Calculate the stack offset: 88 - (4 * parameter_counter)
+	lw t0, 0(sp)
+	li t1, 4
+	mul t0, t0, t1
+	li t1, 88
+	sub a0, t1, t0
+	_write_i();
+
+	_write_c('(');
+	_write_z(@asm_sp);
+	_write_c(')');
+	_write_c('\n');
+
+	lw a0, 0(sp)
+	addi a0, a0, 1
+	sw a0, 0(sp)
+
+	li t0, 8
+	bne a0, t0, .compile_procedure_prologue_loop
+end;
+
 proc _compile_procedure();
 begin
 	# Skip "proc ".
@@ -883,8 +959,7 @@ begin
 
 	_write_token(v0);
 
-	la a0, asm_type_function
+	_write_z(@asm_type_function);
-	_write_z();
 
 	# Write procedure label, _procedure_name:
 	_write_token(v0);
@@ -896,8 +971,7 @@ begin
 	addi a0, a0, 10
 	_advance_token();
 
-	_write_z(@asm_prologue);
+	_compile_procedure_prologue();
-
 	_compile_procedure_body();
 
 	# Write the epilogue.

boot/stage6.elna

@@ -4,11 +4,10 @@
 
 # Stage4 compiler.
 #
-# - Taking value of local and global variables. Variables that doesn't begin
+# - Stack size increased to 128 per procedure.
-#   with "v" are considered global.
+#   7 words on the stack, 92 - 120, are reversed for procedure arguments (caller side).
-# - Simple variable assignment, e.g. v0 := 5 or v0 := global_variable;
+#   7 words on the stack, 64 - 92, are reserved for procedure parameters (callee side).
-#   7 words on the stack, 28 - 56, are reversed for procedure arguments (caller side).
+#   The first parameter is in 88, the second in 84 and so forth.
-# - Take address unary operation "@".
 
 .section .rodata
 
@@ -37,10 +36,10 @@ keyword_begin: .ascii "begin"
 keyword_var: .ascii "var"
 
 .type asm_prologue, @object
-asm_prologue: .string "\taddi sp, sp, -64\n\tsw ra, 60(sp)\n\tsw s0, 56(sp)\n\taddi s0, sp, 64\n"
+asm_prologue: .string "\taddi sp, sp, -128\n\tsw ra, 124(sp)\n\tsw s0, 120(sp)\n\taddi s0, sp, 128\n"
 
 .type asm_epilogue, @object
-asm_epilogue: .string "\tlw ra, 60(sp)\n\tlw s0, 56(sp)\n\taddi sp, sp, 64\n\tret\n"
+asm_epilogue: .string "\tlw ra, 124(sp)\n\tlw s0, 120(sp)\n\taddi sp, sp, 128\n\tret\n"
 
 .type asm_type_directive, @object
 asm_type_directive: .string ".type "
@@ -72,11 +71,8 @@ asm_sw: .string "\tsw "
 .type asm_addi, @object
 asm_addi: .string "\taddi "
 
-.type asm_t0, @object
+.type asm_neg, @object
-asm_t0: .string "t0"
+asm_neg: .string "\tneg "
-
-.type asm_t1, @object
-asm_t1: .string "t1"
 
 .type asm_comma, @object
 asm_comma: .string ", "
@@ -486,7 +482,7 @@ end;
 proc _compile_integer_literal();
 begin
 	_write_z(@asm_li);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_read_token();
@@ -499,7 +495,7 @@ end;
 proc _compile_character_literal();
 begin
 	_write_z(@asm_li);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_write_c('\'');
@@ -532,11 +528,11 @@ begin
 	_compile_designator();
 
 	_write_z(@asm_lw);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_write_c('(');
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 
 	_write_c(')');
 	_write_c('\n');
@@ -551,7 +547,23 @@ begin
 
 end;
 
-proc _compile_expression();
+proc _compile_negate_expression();
+begin
+	# Skip the "-" sign.
+	_advance_token(1);
+	_compile_term();
+
+	_write_z(@asm_neg);
+	_write_register('t', 0);
+
+	_write_z(@asm_comma);
+	_write_register('t', 0);
+
+	_write_c('\n');
+
+end;
+
+proc _compile_term();
 begin
 	la t0, source_code_position
 	lw t0, (t0)
@@ -559,33 +571,45 @@ begin
 	sw a0, 0(sp)
 
 	li t1, '\''
-	beq a0, t1, .compile_expression_character_literal
+	beq a0, t1, .compile_term_character_literal
 
 	li t1, '@'
-	beq a0, t1, .compile_expression_address
+	beq a0, t1, .compile_term_address
+
+	li t1, '-'
+	beq a0, t1, .compile_term_negation
 
 	_is_digit(v0);
-	bnez a0, .compile_expression_integer_literal
+	bnez a0, .compile_term_integer_literal
 
-	goto .compile_expression_variable;
+	goto .compile_term_variable;
 
-.compile_expression_character_literal:
+.compile_term_character_literal:
 	_compile_character_literal();
-	goto .compile_expression_end;
+	goto .compile_term_end;
 
-.compile_expression_integer_literal:
+.compile_term_integer_literal:
 	_compile_integer_literal();
-	goto .compile_expression_end;
+	goto .compile_term_end;
 
-.compile_expression_address:
+.compile_term_address:
 	_compile_address_expression();
-	goto .compile_expression_end;
+	goto .compile_term_end;
 
-.compile_expression_variable:
+.compile_term_negation:
+	_compile_negate_expression();
+	goto .compile_term_end;
+
+.compile_term_variable:
 	_compile_variable_expression();
-	goto .compile_expression_end;
+	goto .compile_term_end;
 
-.compile_expression_end:
+.compile_term_end:
+end;
+
+proc _compile_expression();
+begin
+	_compile_term();
 end;
 
 proc _compile_call();
@@ -617,14 +641,14 @@ begin
 
 	# Save the argument on the stack.
 	_write_z(@asm_sw);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
-	# Calculate the stack offset: 52 - (4 * argument_counter)
+	# Calculate the stack offset: 116 - (4 * argument_counter)
 	lw t0, 8(sp)
 	li t1, 4
 	mul t0, t0, t1
-	li t1, 52
+	li t1, 116
 	sub a0, t1, t0
 	_write_i();
 
@@ -668,11 +692,11 @@ begin
 
 	_write_z(@asm_comma);
 
-	# Calculate the stack offset: 52 - (4 * argument_counter)
+	# Calculate the stack offset: 116 - (4 * argument_counter)
 	lw t0, 8(sp)
 	li t1, 4
 	mul t0, t0, t1
-	li t1, 52
+	li t1, 116
 	sub a0, t1, t0
 	_write_i();
 
@@ -712,7 +736,7 @@ begin
 	_advance_token(1);
 
 	_write_z(@asm_addi);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 	_write_z(@asm_sp);
 	_write_z(@asm_comma);
@@ -733,7 +757,7 @@ end;
 proc _compile_global_designator();
 begin
 	_write_z(@asm_la);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_read_token();
@@ -772,7 +796,7 @@ begin
 
 	# Save the assignee address on the stack.
 	_write_z(@asm_sw);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_write_i(20);
@@ -787,7 +811,7 @@ begin
 	_compile_expression();
 
 	_write_z(@asm_lw);
-	_write_z(@asm_t1);
+	_write_register('t', 1);
 	_write_z(@asm_comma);
 
 	_write_i(20);
@@ -797,11 +821,11 @@ begin
 	_write_c('\n');
 
 	_write_z(@asm_sw);
-	_write_z(@asm_t0);
+	_write_register('t', 0);
 	_write_z(@asm_comma);
 
 	_write_c('(');
-	_write_z(@asm_t1);
+	_write_register('t', 1);
 	_write_c(')');
 end;
 
@@ -855,11 +879,8 @@ end;
 proc _compile_procedure_body();
 begin
 .compile_procedure_body_loop:
-	la a0, source_code_position
+	# 3 is "end" length.
-	lw a0, (a0)
+	_memcmp(source_code_position, @keyword_end, 3);
-	la a1, keyword_end
-	li a2, 3 # "end" length.
-	_memcmp();
 
 	beqz a0, .compile_procedure_body_epilogue
 
@@ -869,6 +890,60 @@ begin
 .compile_procedure_body_epilogue:
 end;
 
+# Writes a regster name to the standard output.
+#
+# Parameters:
+# a0 - Register character.
+# a1 - Register number.
+proc _write_register();
+begin
+	sw a0, 0(sp)
+	sw a1, 4(sp)
+
+	_write_c();
+
+	lw a0, 4(sp)
+	li t0, '0'
+	add a0, a0, t0
+	_write_c();
+end;
+
+proc _compile_procedure_prologue();
+begin
+	_write_z(@asm_prologue);
+
+	v0 := 0;
+
+.compile_procedure_prologue_loop:
+	_write_z(@asm_sw);
+
+	li a0, 'a'
+	lw a1, 0(sp)
+	_write_register();
+
+	_write_z(@asm_comma);
+
+	# Calculate the stack offset: 88 - (4 * parameter_counter)
+	lw t0, 0(sp)
+	li t1, 4
+	mul t0, t0, t1
+	li t1, 88
+	sub a0, t1, t0
+	_write_i();
+
+	_write_c('(');
+	_write_z(@asm_sp);
+	_write_c(')');
+	_write_c('\n');
+
+	lw a0, 0(sp)
+	addi a0, a0, 1
+	sw a0, 0(sp)
+
+	li t0, 8
+	bne a0, t0, .compile_procedure_prologue_loop
+end;
+
 proc _compile_procedure();
 begin
 	# Skip "proc ".
@@ -883,8 +958,7 @@ begin
 
 	_write_token(v0);
 
-	la a0, asm_type_function
+	_write_z(@asm_type_function);
-	_write_z();
 
 	# Write procedure label, _procedure_name:
 	_write_token(v0);
@@ -896,8 +970,7 @@ begin
 	addi a0, a0, 10
 	_advance_token();
 
-	_write_z(@asm_prologue);
+	_compile_procedure_prologue();
-
 	_compile_procedure_body();
 
 	# Write the epilogue.