Support simple variable assignment
This commit is contained in:
238
boot/stage4.elna
238
boot/stage4.elna
@@ -2,14 +2,13 @@
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# v. 2.0. If a copy of the MPL was not distributed with this file, You can
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# obtain one at https://mozilla.org/MPL/2.0/.
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# Stage3 compiler.
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# Stage4 compiler.
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#
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# - Procedures without none or one argument.
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# - Goto statements.
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# - Character and integer literals.
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# - Passing local variables to procedures.
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# - Local variables should have the format: v00,
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# where 00 is its offset from the sp register.
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# - Taking value of local and global variables. Variables that doesn't begin
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# with "v" are considered global.
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# - Simple variable assignment, e.g. v0 := 5 or v0 := global_variable;
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# 7 words on the stack, 28 - 56, are reversed for procedure arguments (caller side).
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# - Take address unary operation "@".
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.section .rodata
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@@ -38,10 +37,10 @@ keyword_begin: .ascii "begin"
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keyword_var: .ascii "var"
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.type asm_prologue, @object
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asm_prologue: .string "\taddi sp, sp, -32\n\tsw ra, 28(sp)\n\tsw s0, 24(sp)\n\taddi s0, sp, 32\n"
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asm_prologue: .string "\taddi sp, sp, -64\n\tsw ra, 60(sp)\n\tsw s0, 56(sp)\n\taddi s0, sp, 64\n"
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.type asm_epilogue, @object
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asm_epilogue: .string "\tlw ra, 28(sp)\n\tlw s0, 24(sp)\n\taddi sp, sp, 32\n\tret\n"
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asm_epilogue: .string "\tlw ra, 60(sp)\n\tlw s0, 56(sp)\n\taddi sp, sp, 64\n\tret\n"
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.type asm_type_directive, @object
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asm_type_directive: .string ".type "
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@@ -64,23 +63,26 @@ asm_li: .string "\tli "
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.type asm_lw, @object
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asm_lw: .string "\tlw "
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.type asm_la, @object
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asm_la: .string "\tla "
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.type asm_sw, @object
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asm_sw: .string "\tsw "
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.type asm_mv, @object
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asm_mv: .string "mv "
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.type asm_addi, @object
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asm_addi: .string "\taddi "
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.type asm_t0, @object
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asm_t0: .string "t0"
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.type asm_a0, @object
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asm_a0: .string "a0"
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.type asm_t1, @object
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asm_t1: .string "t1"
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.type asm_comma, @object
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asm_comma: .string ", "
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.type asm_sp, @object
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asm_sp: .string "(sp)"
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asm_sp: .string "sp"
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.section .bss
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@@ -257,7 +259,7 @@ begin
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_is_upper();
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sw a0, 4(sp)
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_is_lower(v00);
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_is_lower(v0);
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lw t0, 0(sp)
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xori t1, t0, '_'
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@@ -292,7 +294,7 @@ begin
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_is_alpha();
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sw a0, 0(sp)
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_is_digit(v04);
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_is_digit(v4);
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lw a1, 0(sp)
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or a0, a0, a1
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@@ -491,7 +493,7 @@ begin
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la a0, asm_li
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_write_z();
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la a0, asm_a0
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la a0, asm_t0
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_write_z();
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la a0, asm_comma
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@@ -509,7 +511,7 @@ begin
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la a0, asm_li
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_write_z();
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la a0, asm_a0
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la a0, asm_t0
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_write_z();
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la a0, asm_comma
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@@ -542,43 +544,51 @@ end;
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proc _compile_variable_expression();
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begin
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_compile_designator();
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la a0, asm_lw
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_write_z();
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la a0, asm_a0
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la a0, asm_t0
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_write_z();
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la a0, asm_comma
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_write_z();
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_advance_token(1);
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_read_token();
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_write_token();
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_advance_token();
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la a0, asm_sp
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_write_c('(');
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la a0, asm_t0
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_write_z();
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_write_c(')');
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_write_c('\n');
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end;
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proc _compile_address_expression();
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begin
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# Skip the "@" sign.
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_advance_token(1);
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_compile_designator();
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end;
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proc _compile_expression();
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begin
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la t0, source_code_position
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lw t0, (t0)
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lb a0, (t0)
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sw a0, 0(sp)
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li t1, '\''
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beq a0, t1, .compile_expression_character_literal
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li t1, 'v'
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beq a0, t1, .compile_expression_variable
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li t1, '@'
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beq a0, t1, .compile_expression_address
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_is_digit();
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_is_digit(v0);
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bnez a0, .compile_expression_integer_literal
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goto .compile_expression_end;
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goto .compile_expression_variable;
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.compile_expression_character_literal:
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_compile_character_literal();
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@@ -588,9 +598,13 @@ begin
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_compile_integer_literal();
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goto .compile_expression_end;
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.compile_expression_address:
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_compile_address_expression();
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goto .compile_expression_end;
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.compile_expression_variable:
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_compile_variable_expression();
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goto .compile_expression_end;;
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goto .compile_expression_end;
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.compile_expression_end:
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end;
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@@ -628,22 +642,24 @@ begin
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la a0, asm_sw
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_write_z();
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la a0, asm_a0
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la a0, asm_t0
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_write_z();
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la a0, asm_comma
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_write_z();
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# Calculate the stack offset: 20 - (4 * argument_counter)
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# Calculate the stack offset: 52 - (4 * argument_counter)
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lw t0, 8(sp)
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li t1, 4
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mul t0, t0, t1
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li t1, 20
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li t1, 52
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sub a0, t1, t0
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_write_i();
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_write_c('(')
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la a0, asm_sp
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_write_z();
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_write_c(')')
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_write_c('\n');
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@@ -683,17 +699,19 @@ begin
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la a0, asm_comma
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_write_z();
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# Calculate the stack offset: 20 - (4 * argument_counter)
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# Calculate the stack offset: 52 - (4 * argument_counter)
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lw t0, 8(sp)
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li t1, 4
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mul t0, t0, t1
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li t1, 20
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li t1, 52
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sub a0, t1, t0
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_write_i();
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_write_c('(');
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la a0, asm_sp
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_write_z();
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_write_c(')');
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_write_c('\n');
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goto .compile_call_finalize;
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@@ -702,7 +720,7 @@ begin
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la a0, asm_call
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_write_z();
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_write_s(v04, v00);
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_write_s(v4, v0);
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# Skip the right paren.
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_advance_token(1);
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@@ -718,10 +736,143 @@ begin
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la a0, asm_j
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_write_z();
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_write_token(v00);
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_write_token(v0);
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_advance_token();
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end;
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proc _compile_local_designator();
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begin
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# Skip "v" in the local variable name.
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_advance_token(1);
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la a0, asm_addi
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_write_z();
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la a0, asm_t0
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_write_z();
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la a0, asm_comma
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_write_z();
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la a0, asm_sp
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_write_z();
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la a0, asm_comma
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_write_z();
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# Read local variable stack offset and save it.
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la t0, source_code_position
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lw t0, (t0)
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sw t0, 0(sp)
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_read_token();
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sw a0, 4(sp)
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_write_token();
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_advance_token();
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_write_c('\n');
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end;
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proc _compile_global_designator();
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begin
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la a0, asm_la
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_write_z();
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la a0, asm_t0
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_write_z();
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la a0, asm_comma
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_write_z();
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_read_token();
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_write_token();
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_advance_token();
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_write_c('\n');
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end;
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proc _compile_designator();
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begin
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la t0, source_code_position
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lw t0, (t0)
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lb a0, (t0)
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li t1, 'v'
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beq a0, t1, .compile_designator_local
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goto .compile_designator_global;
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.compile_designator_local:
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_compile_local_designator();
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goto .compile_designator_end;
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.compile_designator_global:
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_compile_global_designator();
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goto .compile_designator_end;
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.compile_designator_end:
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end;
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proc _compile_assignment();
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begin
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_compile_designator();
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# Save the assignee address on the stack.
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la a0, asm_sw
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_write_z();
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la a0, asm_t0
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_write_z();
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la a0, asm_comma
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_write_z();
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_write_i(20);
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_write_c('(');
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la a0, asm_sp
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_write_z();
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_write_c(')');
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_write_c('\n');
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# Skip the assignment sign (:=) with surrounding whitespaces.
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_advance_token(4);
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# Compile the assignment.
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_compile_expression();
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la a0, asm_lw
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_write_z();
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la a0, asm_t1
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_write_z();
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la a0, asm_comma
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_write_z();
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_write_i(20);
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_write_c('(');
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la a0, asm_sp
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_write_z();
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_write_c(')');
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_write_c('\n');
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la a0, asm_sw
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_write_z();
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la a0, asm_t0
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_write_z();
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la a0, asm_comma
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_write_z();
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_write_c('(');
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la a0, asm_t1
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_write_z();
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_write_c(')');
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end;
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proc _compile_statement();
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begin
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# This is a call if the statement starts with an underscore.
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@@ -737,6 +888,9 @@ begin
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li t1, 'g'
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beq t0, t1, .compile_statement_goto
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li t1, 'v'
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beq t0, t1, .compile_statement_assignment
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_compile_line();
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goto .compile_statement_end;
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@@ -752,6 +906,12 @@ begin
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goto .compile_statement_semicolon;
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.compile_statement_assignment:
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_advance_token(1);
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_compile_assignment();
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goto .compile_statement_semicolon;
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.compile_statement_semicolon:
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_advance_token(2);
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@@ -789,13 +949,13 @@ begin
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la a0, asm_type_directive
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_write_z();
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_write_token(v00);
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_write_token(v0);
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la a0, asm_type_function
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_write_z();
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# Write procedure label, _procedure_name:
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_write_token(v00);
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_write_token(v0);
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la a0, asm_colon
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_write_z();
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