Added asmc package

src/asmc/resolvePointers.go

@@ -0,0 +1,98 @@
+package asmc
+
+import (
+	"encoding/binary"
+	"fmt"
+	"slices"
+
+	"git.akyoto.dev/cli/q/src/config"
+	"git.akyoto.dev/cli/q/src/fs"
+	"git.akyoto.dev/cli/q/src/sizeof"
+)
+
+// resolvePointers resolves the addresses of all pointers within the code and writes the correct addresses to the code slice.
+func (c *compiler) resolvePointers() {
+restart:
+	for i, pointer := range c.codePointers {
+		address := pointer.Resolve()
+
+		if sizeof.Signed(int64(address)) > int(pointer.Size) {
+			left := c.code[:pointer.Position-Address(pointer.OpSize)]
+			right := c.code[pointer.Position+Address(pointer.Size):]
+			size := pointer.Size + pointer.OpSize
+			opCode := c.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 c.codePointers[i+1:] {
+				following.Position += offset
+			}
+
+			for key, address := range c.codeLabels {
+				if address > pointer.Position {
+					c.codeLabels[key] += offset
+				}
+			}
+
+			c.code = slices.Concat(left, jump, right)
+			goto restart
+		}
+
+		slice := c.code[pointer.Position : pointer.Position+Address(pointer.Size)]
+
+		switch pointer.Size {
+		case 1:
+			slice[0] = uint8(address)
+		case 2:
+			binary.LittleEndian.PutUint16(slice, uint16(address))
+		case 4:
+			binary.LittleEndian.PutUint32(slice, uint32(address))
+		case 8:
+			binary.LittleEndian.PutUint64(slice, uint64(address))
+		}
+	}
+
+	dataStart, _ := fs.Align(c.codeStart+Address(len(c.code)), config.Align)
+
+	for _, pointer := range c.dataPointers {
+		address := config.BaseAddress + Address(dataStart) + pointer.Resolve()
+		slice := c.code[pointer.Position : pointer.Position+4]
+		binary.LittleEndian.PutUint32(slice, uint32(address))
+	}
+
+	if config.TargetOS == config.Windows {
+		importsStart, _ := fs.Align(dataStart+Address(len(c.data)), config.Align)
+
+		for _, pointer := range c.dllPointers {
+			destination := Address(importsStart) + pointer.Resolve()
+			delta := destination - Address(c.codeStart+pointer.Position+Address(pointer.Size))
+			slice := c.code[pointer.Position : pointer.Position+4]
+			binary.LittleEndian.PutUint32(slice, uint32(delta))
+		}
+	}
+}