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|
package code
import (
"encoding/binary"
"fmt"
"math"
)
type Builder struct {
code []byte
debugInfo DebugInfo
relativePcRefs map[int][]int
currentLine int
lineStart int
}
func NewBuilder() Builder {
return Builder{
code: make([]byte, 0, 64),
debugInfo: NewDebugInfo("unknown file"),
relativePcRefs: make(map[int][]int),
lineStart: -1,
currentLine: -1,
}
}
func (b *Builder) AppendOp(op Op) {
b.code = append(b.code, byte(op))
}
func (b *Builder) AppendInt(x int64) {
b.code = append(b.code, make([]byte, 8)...)
binary.LittleEndian.PutUint64(b.code[len(b.code)-8:], uint64(x))
}
func (b *Builder) AppendFloat(x float64) {
b.AppendInt(int64(math.Float64bits(x)))
}
func (b *Builder) AppendString(s string) {
b.code = append(b.code, []byte(s)...)
b.code = append(b.code, 0)
}
func (b *Builder) AppendReferenceToPc(pc int64) {
b.addPcRef(int(pc), b.Len())
b.AppendInt(pc)
}
func (b *Builder) AppendRaw(raw Raw) {
b.code = append(b.code, raw...)
}
func (b *Builder) AppendBuilder(other Builder) {
code := other.code
for pc, refsToPc := range other.relativePcRefs {
newPc := b.Len() + pc
for _, ref := range refsToPc {
valueAtRef := binary.LittleEndian.Uint64(code[ref : ref+8])
if int(valueAtRef) != pc {
panic(fmt.Errorf("reference to pc in builder does not actually reference pc. (pc: %d, value at reference: %d)", pc, valueAtRef))
}
binary.LittleEndian.PutUint64(code[ref:], uint64(newPc))
b.addPcRef(newPc, ref+b.Len())
}
}
b.code = append(b.code, code...)
if other.debugInfo.pcToLine.Len() != 0 || other.currentLine != -1 || other.lineStart != -1 {
panic("appending debug infos not implemented yet")
}
}
func (b *Builder) AppendBuilderWithoutAdjustingReferences(other Builder) {
code := other.code
for pc, refsToPc := range other.relativePcRefs {
for _, ref := range refsToPc {
b.addPcRef(pc, ref+b.Len())
}
}
b.code = append(b.code, code...)
if other.debugInfo.pcToLine.Len() != 0 || other.currentLine != -1 || other.lineStart != -1 {
panic("appending debug infos not implemented yet")
}
}
func (b *Builder) StartLine(line int) {
if b.lineStart != -1 {
panic("line already started")
}
b.currentLine = line
b.lineStart = b.Len()
}
func (b *Builder) EndLine() {
defer func() {
b.currentLine = -1
b.lineStart = -1
}()
if b.lineStart == -1 {
panic("line not started")
}
if b.lineStart == b.Len() {
return
}
b.debugInfo.AppendLine(b.Len()-1, b.currentLine)
}
func (b *Builder) SetInt(at int, x int64) {
binary.LittleEndian.PutUint64(b.code[at:], uint64(x))
}
func (b *Builder) Code() Raw {
return Raw(b.code)
}
func (b *Builder) Len() int {
return len(b.code)
}
func (b *Builder) Build() Code {
return New(b.code, b.debugInfo)
}
func (b *Builder) addPcRef(pc int, at int) {
refs, ok := b.relativePcRefs[pc]
if ok {
refs = append(refs, at)
} else {
refs = make([]int, 1)
refs[0] = at
}
b.relativePcRefs[pc] = refs
}
|
