Implemented basic support for function pointers

examples/thread/thread.q

@@ -0,0 +1,23 @@
+import mem
+import sys
+
+main() {
+	start()
+	start()
+	start()
+	thread()
+}
+
+start() {
+	size := 4096
+	stack := mem.alloc(size)
+	pointer := stack + size - 8
+	store(pointer, 8, thread)
+	sys.clone(0x100 | 0x200 | 0x400 | 0x800 | 0x8000 | 0x10000 | 0x80000000, pointer)
+}
+
+thread() {
+	sys.write(1, "[ ] start\n", 10)
+	sys.write(1, "[x] end\n", 8)
+	sys.exit(0)
+}

lib/sys/sys_linux.q

@@ -22,6 +22,10 @@ munmap(address Pointer, length Int) -> Int {
 	return syscall(11, address, length)
 }
 
+nanosleep(requested Pointer, remaining Pointer) -> Int {
+	return syscall(35, requested, remaining)
+}
+
 clone(flags Int, stack Pointer) -> Int {
 	return syscall(56, flags, stack)
 }

src/asm/Finalize.go

@@ -26,6 +26,7 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
 		dataLabels   map[string]Address
 		codePointers []*Pointer
 		dataPointers []*Pointer
+		funcPointers []*Pointer
 		dllPointers  []*Pointer
 	)
 
@@ -293,6 +294,33 @@ func (a Assembler) Finalize(dlls dll.List) ([]byte, []byte) {
 				} else {
 					code = x64.StoreDynamicNumber(code, operands.Address.Base, operands.Address.OffsetRegister, operands.Address.Length, operands.Number)
 				}
+			case *MemoryLabel:
+				start := len(code)
+
+				if operands.Address.OffsetRegister == math.MaxUint8 {
+					code = x64.StoreNumber(code, operands.Address.Base, operands.Address.Offset, operands.Address.Length, 0b00_00_00_00)
+				} else {
+					code = x64.StoreDynamicNumber(code, operands.Address.Base, operands.Address.OffsetRegister, operands.Address.Length, 0b00_00_00_00)
+				}
+
+				size := 4
+				opSize := len(code) - size - start
+				memLabel := x.Data.(*MemoryLabel)
+
+				funcPointers = append(funcPointers, &Pointer{
+					Position: Address(len(code) - size),
+					OpSize:   uint8(opSize),
+					Size:     uint8(size),
+					Resolve: func() Address {
+						destination, exists := codeLabels[memLabel.Label]
+
+						if !exists {
+							panic("unknown label")
+						}
+
+						return Address(destination)
+					},
+				})
 			case *MemoryRegister:
 				if operands.Address.OffsetRegister == math.MaxUint8 {
 					code = x64.StoreRegister(code, operands.Address.Base, operands.Address.Offset, operands.Address.Length, operands.Register)
@@ -397,6 +425,12 @@ restart:
 	dataStart, _ := fs.Align(codeStart+Address(len(code)), config.Align)
 	data, dataLabels = a.Data.Finalize()
 
+	for _, pointer := range funcPointers {
+		address := config.BaseAddress + Address(codeStart) + pointer.Resolve()
+		slice := code[pointer.Position : pointer.Position+4]
+		binary.LittleEndian.PutUint32(slice, uint32(address))
+	}
+
 	for _, pointer := range dataPointers {
 		address := config.BaseAddress + Address(dataStart) + pointer.Resolve()
 		slice := code[pointer.Position : pointer.Position+4]

src/asm/MemoryLabel.go

@@ -0,0 +1,27 @@
+package asm
+
+import (
+	"fmt"
+)
+
+// MemoryLabel operates with a memory address and a number.
+type MemoryLabel struct {
+	Address Memory
+	Label   string
+}
+
+// String returns a human readable version.
+func (data *MemoryLabel) String() string {
+	return fmt.Sprintf("%dB [%s+%s+%d], %s", data.Address.Length, data.Address.Base, data.Address.OffsetRegister, data.Address.Offset, data.Label)
+}
+
+// MemoryLabel adds an instruction with a memory address and a label.
+func (a *Assembler) MemoryLabel(mnemonic Mnemonic, address Memory, label string) {
+	a.Instructions = append(a.Instructions, Instruction{
+		Mnemonic: mnemonic,
+		Data: &MemoryLabel{
+			Address: address,
+			Label:   label,
+		},
+	})
+}

src/core/CompileCall.go

@@ -29,6 +29,10 @@ func (f *Function) CompileCall(root *expression.Expression) (*Function, error) {
 		if name == "syscall" {
 			return nil, f.CompileSyscall(root)
 		}
+
+		if name == "store" {
+			return nil, f.CompileMemoryStore(root)
+		}
 	} else {
 		pkg = nameNode.Children[0].Token.Text(f.File.Bytes)
 		name = nameNode.Children[1].Token.Text(f.File.Bytes)

src/core/CompileMemoryStore.go

@@ -0,0 +1,33 @@
+package core
+
+import (
+	"math"
+
+	"git.akyoto.dev/cli/q/src/asm"
+	"git.akyoto.dev/cli/q/src/errors"
+	"git.akyoto.dev/cli/q/src/expression"
+)
+
+// CompileMemoryStore ...
+func (f *Function) CompileMemoryStore(root *expression.Expression) error {
+	parameters := root.Children[1:]
+	name := parameters[0].Token.Text(f.File.Bytes)
+	numBytes, _ := f.Number(parameters[1].Token)
+	value := parameters[2]
+	variable := f.VariableByName(name)
+
+	if variable == nil {
+		return errors.New(&errors.UnknownIdentifier{Name: name}, f.File, parameters[0].Token.Position)
+	}
+
+	defer f.UseVariable(variable)
+
+	memory := asm.Memory{
+		Base:           variable.Register,
+		OffsetRegister: math.MaxUint8,
+		Length:         byte(numBytes),
+	}
+
+	_, err := f.ExpressionToMemory(value, memory)
+	return err
+}

src/core/ExpressionToMemory.go

@@ -1,35 +1,53 @@
 package core
 
 import (
+	"fmt"
+
 	"git.akyoto.dev/cli/q/src/asm"
 	"git.akyoto.dev/cli/q/src/errors"
 	"git.akyoto.dev/cli/q/src/expression"
 	"git.akyoto.dev/cli/q/src/sizeof"
+	"git.akyoto.dev/cli/q/src/token"
 	"git.akyoto.dev/cli/q/src/types"
 )
 
 // ExpressionToMemory puts the result of an expression into the specified memory address.
 func (f *Function) ExpressionToMemory(node *expression.Expression, memory asm.Memory) (*types.Type, error) {
-	if node.IsLeaf() && node.Token.IsNumeric() {
-		number, err := f.Number(node.Token)
-
-		if err != nil {
-			return nil, err
+	if node.IsLeaf() {
+		if node.Token.Kind == token.Identifier {
+			f.MemoryLabel(asm.STORE, memory, fmt.Sprintf("%s.%s", f.Package, node.Token.Text(f.File.Bytes)))
+			return types.Pointer, nil
 		}
 
-		size := byte(sizeof.Signed(int64(number)))
+		if node.Token.IsNumeric() {
+			number, err := f.Number(node.Token)
 
-		if size != memory.Length {
-			return nil, errors.New(&errors.NumberExceedsBounds{Number: number, ExpectedSize: memory.Length, Size: size}, f.File, node.Token.Position)
+			if err != nil {
+				return nil, err
+			}
+
+			size := byte(sizeof.Signed(int64(number)))
+
+			if size != memory.Length {
+				return nil, errors.New(&errors.NumberExceedsBounds{Number: number, ExpectedSize: memory.Length, Size: size}, f.File, node.Token.Position)
+			}
+
+			f.MemoryNumber(asm.STORE, memory, number)
+			return types.Int, nil
 		}
-
-		f.MemoryNumber(asm.STORE, memory, number)
-		return types.Int, nil
 	}
 
-	tmp := f.NewRegister()
-	defer f.FreeRegister(tmp)
-	typ, err := f.ExpressionToRegister(node, tmp)
-	f.MemoryRegister(asm.STORE, memory, tmp)
+	typ, register, isTemporary, err := f.Evaluate(node)
+
+	if err != nil {
+		return nil, err
+	}
+
+	f.MemoryRegister(asm.STORE, memory, register)
+
+	if isTemporary {
+		f.FreeRegister(register)
+	}
+
 	return typ, err
 }

src/register/MemoryLabel.go

@@ -0,0 +1,8 @@
+package register
+
+import "git.akyoto.dev/cli/q/src/asm"
+
+func (f *Machine) MemoryLabel(mnemonic asm.Mnemonic, a asm.Memory, b string) {
+	f.Assembler.MemoryLabel(mnemonic, a, b)
+	f.postInstruction()
+}