cli/q
Code Issues 1 Pull Requests Activity

Implemented 32-bit jumps

Browse Source
This commit is contained in:
Eduard Urbach
2024-07-10 15:01:46 +02:00
parent d3436b13a5
commit e24d9ebb50
10 changed files with 253 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
src/build/asm/Assembler.go
View File

@ -2,6 +2,7 @@ package asm
import (
"encoding/binary"
"fmt"
"git.akyoto.dev/cli/q/src/build/arch/x64"
)
@ -16,7 +17,7 @@ func (a Assembler) Finalize() ([]byte, []byte) {
code := make([]byte, 0, len(a.Instructions)*8)
data := make([]byte, 0, 16)
labels := map[string]Address{}
pointers := []Pointer{}
pointers := []*Pointer{}
for _, x := range a.Instructions {
switch x.Mnemonic {
@ -53,8 +54,9 @@ func (a Assembler) Finalize() ([]byte, []byte) {
label := x.Data.(*Label)
nextInstructionAddress := Address(len(code))
pointers = append(pointers, Pointer{
pointers = append(pointers, &Pointer{
Position: Address(len(code) - size),
OpSize: 1,
Size: uint8(size),
Resolve: func() Address {
destination, exists := labels[label.Name]
@ -101,8 +103,9 @@ func (a Assembler) Finalize() ([]byte, []byte) {
label := x.Data.(*Label)
nextInstructionAddress := Address(len(code))
pointers = append(pointers, Pointer{
pointers = append(pointers, &Pointer{
Position: Address(len(code) - size),
OpSize: 1,
Size: uint8(size),
Resolve: func() Address {
destination, exists := labels[label.Name]
@ -153,10 +156,55 @@ func (a Assembler) Finalize() ([]byte, []byte) {
// dataStart := config.BaseAddress + config.CodeOffset + Address(len(code))
for _, pointer := range pointers {
slice := code[pointer.Position : pointer.Position+Address(pointer.Size)]
restart:
for i, pointer := range pointers {
address := pointer.Resolve()
if x64.SizeOf(int64(address)) > int(pointer.Size) {
left := code[:pointer.Position-Address(pointer.OpSize)]
right := code[pointer.Position+Address(pointer.Size):]
size := pointer.Size + pointer.OpSize
opCode := code[pointer.Position-Address(pointer.OpSize)]
var jump []byte
switch opCode {
case 0x74: // JE
jump = []byte{0x0F, 0x84}
case 0x75: // JNE
jump = []byte{0x0F, 0x85}
case 0x7C: // JL
jump = []byte{0x0F, 0x8C}
case 0x7D: // JGE
jump = []byte{0x0F, 0x8D}
case 0x7E: // JLE
jump = []byte{0x0F, 0x8E}
case 0x7F: // JG
jump = []byte{0x0F, 0x8F}
case 0xEB: // JMP
jump = []byte{0xE9}
default:
panic(fmt.Errorf("failed to increase pointer size for instruction 0x%x", opCode))
}
pointer.Position += Address(len(jump) - int(pointer.OpSize))
pointer.OpSize = uint8(len(jump))
pointer.Size = 4
jump = binary.LittleEndian.AppendUint32(jump, uint32(address))
offset := Address(len(jump)) - Address(size)
for _, following := range pointers[i+1:] {
following.Position += offset
}
code = append(left, jump...)
code = append(code, right...)
goto restart
}
slice := code[pointer.Position : pointer.Position+Address(pointer.Size)]
switch pointer.Size {
case 1:
slice[0] = uint8(address)