289 lines
6.9 KiB
Go
289 lines
6.9 KiB
Go
package vm
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import (
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"context"
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"fmt"
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"log"
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"git.defalsify.org/festive/resource"
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"git.defalsify.org/festive/state"
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)
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//type Runner func(instruction []byte, st state.State, rs resource.Resource, ctx context.Context) (state.State, []byte, error)
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// Run extracts individual op codes and arguments and executes them.
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//
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// Each step may update the state.
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//
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// On error, the remaining instructions will be returned. State will not be rolled back.
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func Run(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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running := true
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for running {
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op, bb, err := opSplit(b)
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if err != nil {
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return b, err
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}
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b = bb
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log.Printf("execute code %x (%s) %x", op, OpcodeString[op], b)
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switch op {
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case CATCH:
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b, err = RunCatch(b, st, rs, ctx)
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case CROAK:
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b, err = RunCroak(b, st, rs, ctx)
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case LOAD:
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b, err = RunLoad(b, st, rs, ctx)
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case RELOAD:
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b, err = RunReload(b, st, rs, ctx)
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case MAP:
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b, err = RunMap(b, st, rs, ctx)
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case MOVE:
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b, err = RunMove(b, st, rs, ctx)
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case INCMP:
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b, err = RunInCmp(b, st, rs, ctx)
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case MSIZE:
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b, err = RunMSize(b, st, rs, ctx)
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case MOUT:
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b, err = RunMOut(b, st, rs, ctx)
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case MNEXT:
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b, err = RunMNext(b, st, rs, ctx)
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case MPREV:
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b, err = RunMPrev(b, st, rs, ctx)
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case HALT:
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b, err = RunHalt(b, st, rs, ctx)
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return b, err
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default:
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err = fmt.Errorf("Unhandled state: %v", op)
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}
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if err != nil {
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return b, err
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}
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if len(b) == 0 {
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b, err = RunDeadCheck(b, st, rs, ctx)
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if err != nil {
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return b, err
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}
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}
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if len(b) == 0 {
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return []byte{}, nil
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}
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}
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return b, nil
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}
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// RunDeadCheck determines whether a state of empty bytecode should result in termination.
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//
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// If there is remaining bytecode, this method is a noop.
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//
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// If input has not been matched, a default invalid input page should be generated aswell as a possiblity of return to last screen (or exit).
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//
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// If the termination flag has been set but not yet handled, execution is allowed to terminate.
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func RunDeadCheck(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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if len(b) > 0 {
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return b, nil
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}
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log.Printf("no code remaining, let's check if we terminate")
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r, err := st.MatchFlag(state.FLAG_TERMINATE, false)
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if err != nil {
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panic(err)
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}
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if r {
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return b, nil
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}
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location := st.Where()
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if location == "" {
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return b, fmt.Errorf("dead runner with no current location")
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}
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b = NewLine(nil, MOVE, []string{"_catch"}, nil, nil)
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log.Printf("code is now %x", b)
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return b, nil
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}
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// RunMap executes the MAP opcode
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func RunMap(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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sym, b, err := ParseMap(b)
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err = st.Map(sym)
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return b, err
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}
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// RunMap executes the CATCH opcode
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func RunCatch(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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log.Printf("zzz %x", b)
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sym, sig, mode, b, err := ParseCatch(b)
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if err != nil {
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return b, err
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}
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r, err := st.MatchFlag(sig, mode)
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if err != nil {
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return b, err
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}
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if r {
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log.Printf("catch at flag %v, moving to %v", sig, sym) //bitField, d)
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st.Down(sym)
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b = []byte{}
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}
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return b, nil
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}
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// RunMap executes the CROAK opcode
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func RunCroak(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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sig, mode, b, err := ParseCroak(b)
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if err != nil {
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return b, err
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}
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r, err := st.MatchFlag(sig, mode)
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if err != nil {
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return b, err
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}
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if r {
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log.Printf("croak at flag %v, purging and moving to top", sig)
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st.Reset()
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b = []byte{}
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}
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return []byte{}, nil
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}
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// RunLoad executes the LOAD opcode
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func RunLoad(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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sym, sz, b, err := ParseLoad(b)
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if err != nil {
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return b, err
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}
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r, err := refresh(sym, rs, ctx)
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if err != nil {
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return b, err
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}
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err = st.Add(sym, r, uint16(sz))
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return b, err
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}
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// RunLoad executes the RELOAD opcode
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func RunReload(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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sym, b, err := ParseReload(b)
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if err != nil {
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return b, err
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}
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r, err := refresh(sym, rs, ctx)
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if err != nil {
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return b, err
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}
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st.Update(sym, r)
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return b, nil
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}
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// RunLoad executes the MOVE opcode
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func RunMove(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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sym, b, err := ParseMove(b)
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if err != nil {
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return b, err
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}
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if sym == "_" {
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st.Up()
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sym = st.Where()
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} else {
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st.Down(sym)
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}
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code, err := rs.GetCode(sym)
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if err != nil {
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return b, err
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}
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log.Printf("loaded additional code: %x", code)
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b = append(b, code...)
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return b, nil
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}
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// RunIncmp executes the INCMP opcode
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func RunInCmp(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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sym, target, b, err := ParseInCmp(b)
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if err != nil {
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return b, err
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}
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v, err := st.GetFlag(state.FLAG_INMATCH)
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if err != nil {
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return b, err
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}
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if v {
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return b, nil
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}
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input, err := st.GetInput()
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if err != nil {
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return b, err
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}
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if sym != string(input) {
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return b, nil
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}
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log.Printf("input match for '%s'", input)
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_, err = st.SetFlag(state.FLAG_INMATCH)
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st.Down(target)
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code, err := rs.GetCode(target)
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if err != nil {
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return b, err
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}
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log.Printf("loaded additional code: %x", code)
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b = append(b, code...)
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return b, err
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}
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// RunHalt executes the HALT opcode
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func RunHalt(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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var err error
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b, err = ParseHalt(b)
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if err != nil {
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return b, err
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}
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log.Printf("found HALT, stopping")
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_, err = st.ResetFlag(state.FLAG_INMATCH)
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return b, err
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}
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// RunMSize executes the HALT opcode
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func RunMSize(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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log.Printf("WARNING MSIZE not yet implemented")
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_, _, b, err := ParseMSize(b)
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return b, err
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}
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// RunMNext executes the MNEXT opcode
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func RunMNext(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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selector, display, b, err := ParseMNext(b)
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if err != nil {
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return b, err
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}
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err = rs.SetMenuBrowse(selector, display, false)
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return b, err
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}
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// RunMPrev executes the MPREV opcode
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func RunMPrev(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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selector, display, b, err := ParseMPrev(b)
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if err != nil {
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return b, err
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}
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err = rs.SetMenuBrowse(selector, display, false)
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return b, err
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}
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// RunMOut executes the MOUT opcode
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func RunMOut(b []byte, st *state.State, rs resource.Resource, ctx context.Context) ([]byte, error) {
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choice, title, b, err := ParseMOut(b)
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if err != nil {
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return b, err
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}
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err = rs.PutMenu(choice, title)
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return b, err
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}
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// retrieve data for key
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func refresh(key string, rs resource.Resource, ctx context.Context) (string, error) {
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fn, err := rs.FuncFor(key)
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if err != nil {
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return "", err
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}
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if fn == nil {
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return "", fmt.Errorf("no retrieve function for external symbol %v", key)
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}
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return fn(ctx)
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}
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