diff options
Diffstat (limited to 'assemble.go')
| -rwxr-xr-x | assemble.go | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/assemble.go b/assemble.go new file mode 100755 index 0000000..98af916 --- /dev/null +++ b/assemble.go @@ -0,0 +1,281 @@ +package main + +import ( + "bufio" + "encoding/binary" + "fmt" + "os" + "regexp" + "strconv" + "strings" +) + +var isText bool = true + +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(inst []string, pc int32) ([]byte, error) { + var ret uint32 = 0 + var imm int16 + bytes := make([]byte, 4) + for _, s := range inst { + switch s { + case "syscall": + binary.NativeEndian.PutUint32(bytes, 12) + return bytes, nil + case "nop": + binary.NativeEndian.PutUint32(bytes, 0) + return bytes, nil + } + } + + function := Instructions[inst[0]] + if function.isRtype && function.opcode == 8 { + ret = (RegNums[inst[1]] << 21) | function.opcode + } else if function.isRtype { + ret = (RegNums[inst[2]] << 21) | (RegNums[inst[3]] << + 16) | (RegNums[inst[1]] << 11) | function.opcode + } else if function.opcode == 2 || function.opcode == 3 { + label, _ := labels[inst[1]] + ret = (function.opcode << 26) | uint32(label&0x03FFFFFF) + } else if function.opcode == 35 || function.opcode == 43 { + immReg, err := regexp.Compile("^[0-9]+") + if err != nil { + return nil, err + } + regReg, err := regexp.Compile("\\$([a-z]|[0-9])+") + if err != nil { + return nil, err + } + t, err := strconv.Atoi(immReg.FindString(inst[2])) + if err != nil { + return nil, err + } + imm = int16(t) + reg := regReg.FindString(inst[2]) + ret = (function.opcode << 26) | (RegNums[reg] << 21) | + (RegNums[inst[1]] << 16) | (0xFFFF & uint32(imm)) + } else { + addr, isLabel := labels[inst[3]] + if isLabel { + imm = int16(int32(addr) - pc - 12) + } else { + i, err := strconv.Atoi(inst[3]) + if err != nil { + return nil, err + } + imm = int16(i) + } + ret = (function.opcode << 26) | (RegNums[inst[2]] << 21) | + (RegNums[inst[1]] << 16) | (0xFFFF & uint32(imm)) + } + binary.NativeEndian.PutUint32(bytes, ret) + return bytes, nil +} + +func EncodeData(line []string) ([]byte, error) { + var size int + var err error = nil + var data int64 + isString := false + isData := false + nullTerm := false + + line[1] = strings.ReplaceAll(line[1], "\"", "") + + switch line[0] { + case ".space": + size, err = strconv.Atoi(line[1]) + case ".word": + size = 4 + isData = true + case ".byte": + size = 1 + isData = true + case ".half": + size = 2 + isData = true + case ".asciiz": + size = len(line[1]) + 1 + isString = true + nullTerm = true + case ".ascii": + size = len(line[1]) + isString = true + } + if err != nil { + return nil, err + } + bytes := make([]byte, size) + + if isData { + if strings.Contains(line[1], "0x") { + line[1] = strings.ReplaceAll(line[1], "0x", "") + var t uint64 + t, err = strconv.ParseUint(line[1], 16, size*8) + data = int64(t) + } else { + data, err = strconv.ParseInt(line[1], 10, size*8) + } + if err != nil { + return nil, err + } + switch size { + case 1: + bytes[0] = uint8(data) + case 2: + binary.NativeEndian.PutUint16(bytes, uint16(data)) + case 4: + binary.NativeEndian.PutUint32(bytes, uint32(data)) + } + } else if isString { + if nullTerm { + for i, b := range []byte(line[1]) { + bytes[i] = b + } + bytes[size-1] = 0 + } else { + bytes = []byte(line[1]) + } + } + + return bytes, nil +} + +func Assemble(path string) { + file, err := os.Open(path) + if err != nil { + panic(err) + } + defer file.Close() + + out, err := os.Create(strings.ReplaceAll(path, ".asm", ".bin")) + if err != nil { + panic(err) + } + defer out.Close() + + scanner := bufio.NewScanner(file) + for i := 0; scanner.Scan(); i += 4 { + var s string = scanner.Text() + if s == "" { + i -= 4 + continue + } else if s == ".data" { + isText = false + continue + } else if s == ".text" { + isText = true + continue + } + + inst, err := Parse(s) + if err != nil { + panic(err) + } + + _, isLabel := labels[strings.ReplaceAll(inst[0], ":", "")] + if isLabel { + inst = inst[1:] + } + + if len(inst) == 0 || (len(inst) == 1 && inst[0] == "") { + i -= 4 + continue + } + + var bytes []byte + if isText { + bytes, err = Encode(inst, int32(i)) + } else { + bytes, err = EncodeData(inst) + } + if err != nil { + fmt.Fprintf(os.Stderr, "while encoding %s: %v", s, err) + panic(err) + } + if _, err = out.Write(bytes); err != nil { + panic(err) + } + } + + /* + // Write the new starting PC into the header + if _, err := out.Seek(0, io.SeekStart); err != nil { + panic(err) + } + */ + + if err := scanner.Err(); err != nil { + panic(err) + } +} |