A high-level simpletron instructions compiler written in Java.
- (@mavyfaby) Maverick Fabroa
- Dennis Durano
- Compile high-level simpletron into low-level instructions.
- Dynamic branching with
@branch_nameanywhere in the program. - Evaluate arithmetic expressions.
- Declare variables anywhere.
- Include only used variables to improve memory efficiency.
- Show error if variable declared but doesn't have a value.
- Detect whether the variable already exists.
- Detect whether the variable is already declared.
- Detect whether the instruction is valid.
- Single line comment with
>character. - Append HALT instruction at the end of the program if not explicitly added.
A = 10
B = 10
C = 10
D = A + B + C
WRITE D
HALT
will be compiled to:
2008
3009
2111
2011
3010
2111
1111
4300
10
10
10
0Note: HALT (43) is added at the end of the program if not explicitly added in the high-level instructions.
Copyright (C) 2022 Maverick Fabroa <[email protected]>
This file is part of the High-level Simpletron Compiler project.
The High-level Simpletron Compiler project can NOT be copied and/or distributed without the express permission of Maverick Fabroa <[email protected]>.
| Instruction | OpCode | Description |
|---|---|---|
| READ | 10 | Read a word from the keyboard into a specific location in memory. |
| WRITE | 11 | Write a word from a specific location in memory to the screen. |
| LOAD | 20 | Load a word from a specific location in memory into the accumulator. |
| STORE | 21 | Store a word from the accumulator into a specific location in memory. |
| ADD | 30 | Add a word from a specific location in memory to the word in the accumulator (leave the result in the accumulator). |
| SUBTRACT | 31 | Subtract a word from a specific location in memory from the word in the accumulator (leave the result in the accumulator). |
| BRANCH | 40 | Branch to a specific location in memory. |
| BRANCHNEG | 41 | Branch to a specific location in memory if the accumulator is negative. |
| BRANCHZERO | 42 | Branch to a specific location in memory if the accumulator is zero. |
| HALT | 43 | Halt the program. |
My pseudocode for compiling high-level simpletron instructions into low-level instructions:
if program is empty
return error
for each line in program
get current line and trim
if current line is a comment or empty
continue
if current line is has an equal sign (e.g. A = 10)
if it has a plus or minus operator (e.g. A = B + C - D)
Split the line by equal sign (e.g [ A, B + C - D ])
Split the 2nd value by plus and minus operator (e.g [ B, C, D ])
for each element in the 2nd value
if element is empty (e.g [ A, , C ])
then it's not an expression
break
if it's an expression (e.g A = B + C - D)
remove all spaces (e.g A=B+C-D)
split the expression by equal sign (e.g [ A, B+C-D ])
get the variable name (A)
get the expression (B+C-D)
declare result expression
declare current variable as empty string
for every character in the expression
if character is a plus or minus operator
add the variable to the result expression
add the operator to the result expression
continue
otherwise, add the character to the current variable
add the last variable to the result expression
if the expression's variable name doesn't exist
add the expression's variable name to the variable list
for every element in the expression (e.g. [B+C-D])
if element is not an operator
get the 1st variable name (e.g. B)
get the operator (e.g. +)
get the 2nd variable name (e.g. C)
get the 1st variable's address
get the 2nd variable's address
if the 1st variable doesn't exist
show error
if the 2nd variable doesn't exist
show error
add LOAD opcode to output
add operator's opcode (e.g ADD or SUBTRACT) to output
add STORE opcode to output
if first evaluation
add 1st variable's address to operand,
else
add the expressions variable's address
add 2nd variable's address to operand
add the expressions variable's address to operand
continue
otherwise, it's variable declaration (e.g. A = 10)
Split the line by equal sign (e.g [ A, 10 ])
get the variable name (e.g. A)
get the variable value (e.g. 10)
if the variable value is empty
return error
if the variable already exists
return error
add the variable to the variable list
if current line starts with @ (e.g. @branch_name)
remove all spaces
get the branch name (e.g. branch_name)
if the branch name already exists
return error
add the branch name to the branch list
split the current line by space (e.g. [ WRITE, 10 ])
get the instruction (e.g. WRITE)
if the instruction is incomplete
if command not found
return incomplete command error
return unknown command error
if the instruction is valid
get instruction name
get instruction operand if not empty
get instruction's opcode
if command is HALT
add HALT opcode to output
break
set OPERAND = remove all spaces in the operand
if command is a BRANCH
get branch name
if branch has no identifier name
show branch name is missing error
if branch name exist in the branch list
get branch name's address
add the opcode and operand to the output
add -1 to the operand
continue
declare flag for branch name after the branch callee
for each line after the branch callee's line
get current line
remove all spaces in the line
if line starts with @ and the branch name is the same as the branch callee
set address to output length + difference in lines
add opcode and address to output
add -1 to operand
set flag to true
break
if not found
show branch name not found error
continue
for every variable in the variable list
if variable name is the same as the OPERAND
get variable's address
set OPERAND to the variable's address
if operand is same as the processed operand (OPERAND)
show variable not found error
add the opcode and operand to the output
continue
otherwise, show unknown command error
if HALT opcode is not found
add HALT opcode to output
for every variable in the variable list
for every operand in the operand list
if current operand's value is same as the variable's address
if the variable isn't in the output yet
add the variable to the output
set new address of the variable
for every operand in the list of operands
get opcode
get operand
if opcode is a branch instruction
continue
otherwise, add opcode and operand to the output
Copyright (C) 2022 Maverick Fabroa <[email protected]>
This file is part of the High-level Simpletron Compiler project.
The High-level Simpletron Compiler project can NOT be copied and/or distributed without the express permission of Maverick Fabroa <[email protected]>.