Improved x64 encoder
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862598cfc1
commit
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@ -114,17 +114,17 @@ func (f *Function) CompileInstruction(line token.List) error {
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}
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if expr.Token.Kind == token.Operator {
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name := expr.Children[0].Token.Text()
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number, _ := strconv.Atoi(expr.Children[1].Token.Text())
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register := f.Variables[name].Register
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switch expr.Token.Text() {
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case "+=":
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name := expr.Children[0].Token.Text()
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number, _ := strconv.Atoi(expr.Children[1].Token.Text())
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f.Assembler.AddRegisterNumber(f.Variables[name].Register, number)
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f.Assembler.AddRegisterNumber(register, number)
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return nil
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case "-=":
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name := expr.Children[0].Token.Text()
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number, _ := strconv.Atoi(expr.Children[1].Token.Text())
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f.Assembler.SubRegisterNumber(f.Variables[name].Register, number)
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f.Assembler.SubRegisterNumber(register, number)
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return nil
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}
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}
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@ -6,5 +6,5 @@ import (
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// AddRegNum adds a number to the given register.
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func AddRegNum(code []byte, destination cpu.Register, number int) []byte {
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return numberToRegister(0x83, 0x81, 0b000, code, destination, number)
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return numRegReg(code, 0x83, 0x81, 0, byte(destination), number)
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}
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@ -6,5 +6,5 @@ import (
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// SubRegNum subtracts a number from the given register.
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func SubRegNum(code []byte, destination cpu.Register, number int) []byte {
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return numberToRegister(0x83, 0x81, 0b101, code, destination, number)
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return numRegReg(code, 0x83, 0x81, 0b101, byte(destination), number)
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}
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@ -1,24 +1,27 @@
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package x64
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import (
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"math"
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// numRegReg encodes an instruction with up to two registers and a number parameter.
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func numRegReg(code []byte, opCode8 byte, opCode32 byte, reg byte, rm byte, number int) []byte {
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w := byte(1) // Indicates a 64-bit register.
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r := byte(0) // Extension to the "reg" field in ModRM.
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x := byte(0) // Extension to the SIB index field.
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b := byte(0) // Extension to the "rm" field in ModRM or the SIB base (r8 up to r15 use this).
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mod := byte(0b11) // Direct addressing mode, no register offsets.
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"git.akyoto.dev/cli/q/src/build/cpu"
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)
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// numberToRegister encodes an instruction with a register and a number parameter.
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func numberToRegister(opCode8 byte, opCode32 byte, reg byte, code []byte, destination cpu.Register, number int) []byte {
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b := byte(0)
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if destination >= 8 {
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b = 1
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destination -= 8
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if reg > 0b111 {
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r = 1
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reg &= 0b111
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}
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rex := REX(1, 0, 0, b)
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modRM := ModRM(0b11, reg, byte(destination))
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if rm > 0b111 {
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b = 1
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rm &= 0b111
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}
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if number >= math.MinInt8 && number <= math.MaxInt8 {
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rex := REX(w, r, x, b)
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modRM := ModRM(mod, reg, rm)
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if sizeOf(number) == 1 {
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return append(
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code,
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rex,
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20
src/build/arch/x64/sizeOf.go
Normal file
20
src/build/arch/x64/sizeOf.go
Normal file
@ -0,0 +1,20 @@
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package x64
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import "math"
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// sizeOf tells you how many bytes are needed to encode this number.
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func sizeOf(number int) int {
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switch {
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case number >= math.MinInt8 && number <= math.MaxInt8:
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return 1
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case number >= math.MinInt16 && number <= math.MaxInt16:
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return 2
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case number >= math.MinInt32 && number <= math.MaxInt32:
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return 4
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default:
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return 8
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}
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}
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