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package main
import (
"bufio"
"encoding/binary"
"log"
"os"
"strconv"
"strings"
)
var Instructions = map[string]struct {
isRtype bool
opcode uint32
}{
"add": {true, 32},
"addi": {false, 8},
"addiu": {false, 9},
"sub": {true, 34},
"subu": {true, 35},
"mult": {true, 24},
"multu": {true, 25},
"div": {true, 26},
"divu": {true, 27},
"and": {true, 36},
"andi": {false, 12},
"or": {true, 37},
"ori": {false, 13},
"xor": {true, 38},
"xori": {false, 14},
"sll": {true, 0},
"sra": {true, 3},
"srl": {true, 2},
"lw": {false, 35},
"sw": {false, 43},
"slt": {true, 42},
"slti": {false, 10},
"sltiu": {false, 11},
"sltu": {true, 43},
"beq": {false, 4},
"bne": {false, 5},
"j": {false, 2},
"jal": {false, 3},
"jr": {true, 8},
"syscall": {false, 12},
}
var RegNums = map[string]uint32{
"$zero": 0,
"$at": 1,
"$v0": 2,
"$v1": 3,
"$a0": 4,
"$a1": 5,
"$a2": 6,
"$a3": 7,
"$t0": 8,
"$t1": 9,
"$t2": 10,
"$t3": 11,
"$t4": 12,
"$t5": 13,
"$t6": 14,
"$t7": 15,
"$s0": 16,
"$s1": 17,
"$s2": 18,
"$s3": 19,
"$s4": 20,
"$s5": 21,
"$s6": 22,
"$s7": 23,
"$t8": 24,
"$t9": 25,
"$k0": 26,
"$k1": 27,
"$gp": 28,
"$sp": 29,
"$fp": 30,
"$ra": 31,
}
func Encode(instruction string) uint32 {
var ret uint32 = 0
if instruction == "syscall" {
return 12
}
inst := strings.Fields(strings.ReplaceAll(instruction, ",", ""))
if Instructions[inst[0]].isRtype {
ret = (RegNums[inst[2]] << 21) | (RegNums[inst[3]] << 16) |
(RegNums[inst[1]] << 11) | Instructions[inst[0]].opcode
} else {
var imm int32
i, err := strconv.Atoi(inst[3])
if err != nil {
log.Fatal(err)
}
imm = int32(i)
ret = (Instructions[inst[0]].opcode << 26) | (RegNums[inst[2]] << 21) |
(RegNums[inst[1]] << 16) | uint32(imm)
}
return ret
}
func Assemble(path string) {
file, err := os.Open(path)
if err != nil {
log.Fatal(err)
}
defer file.Close()
out, err := os.Create(strings.ReplaceAll(path, ".asm", ".bin"))
if err != nil {
log.Fatal(err)
}
defer out.Close()
scanner := bufio.NewScanner(file)
for scanner.Scan() {
var s string = scanner.Text()
if s != "" {
bs := make([]byte, 4)
binary.BigEndian.PutUint32(bs, Encode(s))
_, err := out.Write(bs)
if err != nil {
log.Fatal(err)
}
}
}
if err := scanner.Err(); err != nil {
log.Fatal(err)
}
}
func main() {
for _, arg := range os.Args[1:] {
Assemble(arg)
}
}
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