413 lines
7.7 KiB
Go
413 lines
7.7 KiB
Go
package asm
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"io"
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"log"
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"math"
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"strconv"
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"strings"
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"github.com/alecthomas/participle/v2"
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"github.com/alecthomas/participle/v2/lexer"
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"git.defalsify.org/vise/vm"
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)
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// Asm assembles bytecode from the vise assembly mini-language.
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type Asm struct {
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Instructions []*Instruction `@@*`
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}
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// Arg holds all parsed argument elements of a single line of assembly code.
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type Arg struct {
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Sym *string `(@Sym Whitespace?)?`
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Size *uint32 `(@Size Whitespace?)?`
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Flag *uint8 `(@Size Whitespace?)?`
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Selector *string `(@Sym Whitespace?)?`
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Desc *string `(Quote ((@Sym | @Size) @Whitespace?)+ Quote Whitespace?)?`
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}
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func flush(b *bytes.Buffer, w io.Writer) (int, error) {
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if w != nil {
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return w.Write(b.Bytes())
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}
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return 0, nil
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}
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func parseDescType(b *bytes.Buffer, arg Arg) (int, error) {
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var rn int
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var err error
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var selector string
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if arg.Flag != nil {
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selector = strconv.FormatUint(uint64(*arg.Flag), 10)
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} else if arg.Selector != nil {
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selector = *arg.Selector
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}
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var size string
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if arg.Size != nil {
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size = strconv.FormatUint(uint64(*arg.Size), 10)
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n, err := writeSym(b, size)
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rn += n
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if err != nil {
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return rn, err
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}
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}
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if arg.Sym != nil {
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n, err := writeSym(b, *arg.Sym)
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rn += n
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if err != nil {
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return rn, err
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}
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}
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if selector != "" {
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n, err := writeSym(b, *arg.Selector)
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rn += n
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if err != nil {
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return rn, err
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}
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}
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n, err := writeSym(b, *arg.Desc)
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rn += n
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if err != nil {
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return rn, err
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}
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return rn, nil
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}
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func parseTwoSym(b *bytes.Buffer, arg Arg) (int, error) {
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var rn int
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var selector string
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var sym string
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if arg.Size != nil {
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selector = strconv.FormatUint(uint64(*arg.Size), 10)
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sym = *arg.Selector
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} else if arg.Selector != nil {
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if *arg.Sym == "*" {
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sym = *arg.Selector
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selector = *arg.Sym
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} else {
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sym = *arg.Sym
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selector = *arg.Selector
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}
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}
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n, err := writeSym(b, selector)
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rn += n
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if err != nil {
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return rn, err
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}
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n, err = writeSym(b, sym)
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rn += n
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if err != nil {
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return rn, err
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}
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return rn, nil
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}
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func parseSig(b *bytes.Buffer, arg Arg) (int, error) {
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var rn int
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n, err := writeSym(b, *arg.Sym)
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rn += n
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if err != nil {
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return rn, err
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}
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n, err = writeSize(b, *arg.Size)
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rn += n
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if err != nil {
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return rn, err
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}
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n, err = b.Write([]byte{uint8(*arg.Flag)})
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rn += n
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if err != nil {
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return rn, err
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}
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return rn, nil
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}
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func parseSized(b *bytes.Buffer, arg Arg) (int, error) {
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var rn int
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n, err := writeSym(b, *arg.Sym)
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rn += n
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if err != nil {
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return rn, err
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}
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n, err = writeSize(b, *arg.Size)
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rn += n
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if err != nil {
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return rn, err
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}
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return rn, nil
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}
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func parseOne(op vm.Opcode, instruction *Instruction, w io.Writer) (int, error) {
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a := instruction.OpArg
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var n_buf int
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var n_out int
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b := bytes.NewBuffer(nil)
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n, err := writeOpcode(b, op)
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n_buf += n
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if err != nil {
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return n_out, err
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}
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// Catch MOUT
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if a.Desc != nil {
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n, err := parseDescType(b, a)
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n_buf += n
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if err != nil {
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return n_out, err
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}
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return flush(b, w)
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}
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// Catch
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if a.Selector != nil {
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log.Printf("entering twosym for %v", op)
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n, err := parseTwoSym(b, a)
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n_buf += n
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if err != nil {
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return n_out, err
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}
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return flush(b, w)
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}
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// Catch CATCH, LOAD
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if a.Size != nil {
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if a.Flag != nil {
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n, err := parseSig(b, a)
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n_buf += n
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if err != nil {
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return n_out, err
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}
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} else {
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n, err := parseSized(b, a)
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n_buf += n
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if err != nil {
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return n_out, err
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}
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}
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return flush(b, w)
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}
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// Catch HALT
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if a.Sym == nil {
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return flush(b, w)
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}
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n, err = writeSym(b, *a.Sym)
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n_buf += n
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return flush(b, w)
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}
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// String implements the String interface.
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func (a Arg) String() string {
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s := "[Arg]"
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if a.Sym != nil {
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s += " Sym: " + *a.Sym
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}
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if a.Size != nil {
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s += fmt.Sprintf(" Size: %v", *a.Size)
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}
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if a.Flag != nil {
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s += fmt.Sprintf(" Flag: %v", *a.Flag)
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}
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if a.Selector != nil {
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s += " Selector: " + *a.Selector
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}
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if a.Desc != nil {
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s += " Description: " + *a.Desc
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}
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return fmt.Sprintf(s)
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}
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// Instruction represents one full line of assembly code.
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type Instruction struct {
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OpCode string `@Ident`
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OpArg Arg `(Whitespace @@)?`
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Comment string `Comment? EOL`
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}
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// String implement the String interface.
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func (i Instruction) String() string {
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return fmt.Sprintf("%s %s", i.OpCode, i.OpArg)
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}
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var (
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asmLexer = lexer.MustSimple([]lexer.SimpleRule{
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{"Comment", `(?:#)[^\n]*`},
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{"Ident", `^[A-Z]+`},
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{"Size", `[0-9]+`},
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{"Sym", `[a-zA-Z_\*\.][a-zA-Z0-9_]*`},
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{"Whitespace", `[ \t]+`},
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{"EOL", `[\n\r]+`},
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{"Quote", `["']`},
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})
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asmParser = participle.MustBuild[Asm](
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participle.Lexer(asmLexer),
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participle.Elide("Comment", "Whitespace"),
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)
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)
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func numSize(n uint32) int {
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v := math.Log2(float64(n))
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return int((v / 8) + 1)
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}
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func writeOpcode(w *bytes.Buffer, op vm.Opcode) (int, error) {
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bn := [2]byte{}
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binary.BigEndian.PutUint16(bn[:], uint16(op))
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n, err := w.Write(bn[:])
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return n, err
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}
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func writeSym(w *bytes.Buffer, s string) (int, error) {
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sz := len(s)
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if sz > 255 {
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return 0, fmt.Errorf("string size %v too big", sz)
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}
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w.Write([]byte{byte(sz)})
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return w.WriteString(s)
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}
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func writeDisplay(w *bytes.Buffer, s string) (int, error) {
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s = strings.Trim(s, "\"'")
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sz := len(s)
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if sz > 255 {
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return 0, fmt.Errorf("string size %v too big", sz)
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}
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w.Write([]byte{byte(sz)})
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return w.WriteString(s)
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}
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func writeSize(w *bytes.Buffer, n uint32) (int, error) {
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if n == 0 {
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return w.Write([]byte{0x01, 0x00})
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}
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bn := [4]byte{}
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sz := numSize(n)
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if sz > 4 {
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return 0, fmt.Errorf("number size %v too big", sz)
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}
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w.Write([]byte{byte(sz)})
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binary.BigEndian.PutUint32(bn[:], n)
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c := 4-sz
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return w.Write(bn[c:])
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}
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// Batcher handles assembly commands that generates multiple instructions, such as menu navigation commands.
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type Batcher struct {
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menuProcessor MenuProcessor
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inMenu bool
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}
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// NewBatcher creates a new Batcher objcet.
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func NewBatcher(mp MenuProcessor) Batcher {
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return Batcher{
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menuProcessor: NewMenuProcessor(),
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}
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}
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// MenuExit generates the instructions for the batch and writes them to the given io.Writer.
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func(bt *Batcher) MenuExit(w io.Writer) (int, error) {
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if !bt.inMenu {
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return 0, nil
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}
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bt.inMenu = false
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b := bt.menuProcessor.ToLines()
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return w.Write(b)
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}
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// MenuAdd adds a new menu instruction to the batcher.
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func(bt *Batcher) MenuAdd(w io.Writer, code string, arg Arg) (int, error) {
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bt.inMenu = true
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var selector string
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var sym string
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if arg.Size != nil {
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selector = strconv.FormatUint(uint64(*arg.Size), 10)
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} else if arg.Selector != nil {
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selector = *arg.Selector
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}
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if selector == "" {
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selector = *arg.Sym
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} else if arg.Sym != nil {
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sym = *arg.Sym
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}
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log.Printf("menu processor add %v '%v' '%v' '%v'", code, selector, *arg.Desc, sym)
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err := bt.menuProcessor.Add(code, selector, *arg.Desc, sym)
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return 0, err
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}
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// Exit is a synonym for MenuExit
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func(bt *Batcher) Exit(w io.Writer) (int, error) {
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return bt.MenuExit(w)
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}
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// Parse one or more lines of assembly code, and write assembled bytecode to the provided writer.
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func Parse(s string, w io.Writer) (int, error) {
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rd := strings.NewReader(s)
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ast, err := asmParser.Parse("file", rd)
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if err != nil {
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return 0, err
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}
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batch := Batcher{
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}
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var rn int
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for _, v := range ast.Instructions {
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log.Printf("parsing line %v: %v", v.OpCode, v.OpArg)
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op, ok := vm.OpcodeIndex[v.OpCode]
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if !ok {
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n, err := batch.MenuAdd(w, v.OpCode, v.OpArg)
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rn += n
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if err != nil {
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return rn, err
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}
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} else {
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n, err := batch.MenuExit(w)
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if err != nil {
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return rn, err
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}
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rn += n
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n, err = parseOne(op, v, w)
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rn += n
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if err != nil {
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return rn, err
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}
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log.Printf("wrote %v bytes for %v", n, v.OpArg)
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}
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}
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n, err := batch.Exit(w)
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rn += n
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if err != nil {
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return rn, err
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}
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rn += n
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return rn, err
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}
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