133 lines
2.3 KiB
Go
133 lines
2.3 KiB
Go
package main
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import (
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"fmt"
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"os"
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"errors"
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)
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const STACK_SIZE = 1024
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type Operation int
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const (
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HALT Operation = 0
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PUSH Operation = 1
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ADD Operation = 2
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SUB Operation = 3
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MUL Operation = 4
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DIV Operation = 5
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)
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type Inst struct {
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Operation Operation
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Operand int
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}
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type Machine struct {
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program []Inst
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stack []int
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ip int
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sp int
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isHalted bool;
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}
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func Constructor() *Machine {
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m := Machine{}
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m.program = make([]Inst, 0)
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m.stack = make([]int, STACK_SIZE)
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m.ip = 0
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m.sp = 0
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m.isHalted = false
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return &m
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}
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func (m* Machine) Push(i Inst) error {
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m.program = append(m.program, i)
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return nil
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}
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func (m* Machine) Execute() error {
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instr := m.program[m.ip]
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switch op := instr.Operation; op {
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case HALT:
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m.isHalted = true
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case PUSH:
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if (m.sp >= STACK_SIZE) {
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return errors.New("Stack Overflow");
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}
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m.stack[m.sp] = instr.Operand
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m.sp++
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m.ip++
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case ADD:
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if (len(m.stack) < 2) {
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return errors.New("Stack size is less than required to execute ADD")
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}
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m.stack[m.sp - 2] += m.stack[m.sp - 1];
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m.sp--
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m.ip++
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case SUB:
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if (len(m.stack) < 2) {
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return errors.New("Stack size is less than required to execute SUB")
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}
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m.stack[m.sp - 2] -= m.stack[m.sp - 1];
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m.sp--
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m.ip++
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case MUL:
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if (len(m.stack) < 2) {
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return errors.New("Stack size is less than required to execute MUL")
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}
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m.stack[m.sp - 2] *= m.stack[m.sp - 1];
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m.sp--
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m.ip++
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case DIV:
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if (len(m.stack) < 2) {
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return errors.New("Stack size is less than required to execute DIV")
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}
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if (m.stack[m.sp - 2] == 0 || m.stack[m.sp - 1] == 0) {
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return errors.New("Divide by zero exception")
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}
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m.stack[m.sp - 2] /= m.stack[m.sp - 1];
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m.sp--
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m.ip++
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}
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return nil
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}
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func (m* Machine) Print() {
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fmt.Println("Stack:");
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for i := 0; i < m.sp; i++ {
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fmt.Println(m.stack[i])
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}
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}
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func main() {
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m := Constructor()
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m.Push(Inst{Operation: PUSH, Operand: 1})
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m.Push(Inst{Operation: PUSH, Operand: 2})
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m.Push(Inst{Operation: ADD})
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m.Push(Inst{Operation: PUSH, Operand: 2})
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m.Push(Inst{Operation: SUB})
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m.Push(Inst{Operation: PUSH, Operand: 6})
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m.Push(Inst{Operation: MUL})
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m.Push(Inst{Operation: PUSH, Operand: 2})
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m.Push(Inst{Operation: DIV})
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m.Push(Inst{Operation: HALT})
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for !m.isHalted {
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m.Print()
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err := m.Execute()
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if err != nil {
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fmt.Fprintf(os.Stderr, "[ERR] %s", err);
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}
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}
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}
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