mirror of
https://github.com/zellyn/go6502.git
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131 lines
3.6 KiB
Go
131 lines
3.6 KiB
Go
package scma
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import (
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"strings"
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"github.com/zellyn/go6502/asm/context"
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"github.com/zellyn/go6502/asm/expr"
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"github.com/zellyn/go6502/asm/flavors/common"
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"github.com/zellyn/go6502/asm/inst"
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"github.com/zellyn/go6502/asm/lines"
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"github.com/zellyn/go6502/asm/opcodes"
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)
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// 40 spaces = comment column
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const commentWhitespacePrefix = " "
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// SCMA implements the S-C Macro Assembler-compatible assembler flavor.
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// See http://www.txbobsc.com/scsc/ and http://stjarnhimlen.se/apple2/
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type SCMA struct {
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common.Base
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}
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func New(sets opcodes.Set) *SCMA {
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a := &SCMA{}
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a.Name = "scma"
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a.OpcodesByName = opcodes.ByName(sets)
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a.LabelChars = common.Letters + common.Digits + ".:"
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a.LabelColons = common.ReqDisallowed
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a.ExplicitARegister = common.ReqDisallowed
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a.SpacesForComment = 2
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a.MsbChars = "/"
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a.ImmediateChars = "#"
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a.CharChars = "'"
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a.MacroArgSep = ","
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a.DefaultOriginVal = 0x0800
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divZeroVal := uint16(0xffff)
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a.DivZeroVal = &divZeroVal
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a.Directives = map[string]common.DirectiveInfo{
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".IN": {inst.TypeInclude, a.ParseInclude, 0},
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".OR": {inst.TypeOrg, a.ParseOrg, 0},
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".TA": {inst.TypeTarget, a.ParseNotImplemented, 0},
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".TF": {inst.TypeNone, nil, 0},
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".EN": {inst.TypeEnd, a.ParseNoArgDir, 0},
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".EQ": {inst.TypeEqu, a.ParseEquate, 0},
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".DA": {inst.TypeData, a.ParseData, inst.VarMixed},
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".HS": {inst.TypeData, a.ParseHexString, inst.VarBytes},
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".AS": {inst.TypeData, a.ParseAscii, inst.VarBytes},
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".AT": {inst.TypeData, a.ParseAscii, inst.VarBytes},
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".BS": {inst.TypeBlock, a.ParseBlockStorage, 0},
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".TI": {inst.TypeNone, nil, 0},
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".LIST": {inst.TypeNone, nil, 0},
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".PG": {inst.TypeNone, nil, 0},
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".DO": {inst.TypeIfdef, a.ParseDo, 0},
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".ELSE": {inst.TypeIfdefElse, a.ParseNoArgDir, 0},
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".FIN": {inst.TypeIfdefEnd, a.ParseNoArgDir, 0},
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".MA": {inst.TypeMacroStart, a.ParseMacroStart, 0},
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".EM": {inst.TypeMacroEnd, a.ParseNoArgDir, 0},
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".US": {inst.TypeNone, a.ParseNotImplemented, 0},
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}
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a.EquateDirectives = map[string]bool{
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".EQ": true,
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}
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a.Operators = map[string]expr.Operator{
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"*": expr.OpMul,
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"/": expr.OpDiv,
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"+": expr.OpPlus,
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"-": expr.OpMinus,
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"<": expr.OpLt,
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">": expr.OpGt,
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"=": expr.OpEq,
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}
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a.ExtraCommenty = func(s string) bool {
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//Comment by virtue of long whitespace prefix
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return strings.HasPrefix(s, commentWhitespacePrefix)
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}
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a.SetAsciiVariation = func(ctx context.Context, in *inst.I, lp *lines.Parse) {
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// For S-C Assembler, leading "-" flips high bit
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invert := lp.Consume("-")
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invertLast := in.Command == ".AT"
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switch {
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case !invert && !invertLast:
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in.Var = inst.VarAscii
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case !invert && invertLast:
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in.Var = inst.VarAsciiFlip
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case invert && !invertLast:
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in.Var = inst.VarAsciiHi
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case invert && invertLast:
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in.Var = inst.VarAsciiHiFlip
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}
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}
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// ParseMacroCall parses a macro call. We expect in.Command to hold
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// the "command column" value, which caused isMacroCall to return
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// true, and the lp to be pointing to the following character
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// (probably whitespace).
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a.ParseMacroCall = func(ctx context.Context, in inst.I, lp *lines.Parse) (inst.I, bool, error) {
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if in.Command == "" || in.Command[0] != '>' {
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// not a macro call
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return in, false, nil
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}
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in.Type = inst.TypeMacroCall
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in.Command = in.Command[1:]
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lp.Consume(common.Whitespace)
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for {
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s, err := a.ParseMacroArg(in, lp)
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if err != nil {
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return in, true, err
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}
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in.MacroArgs = append(in.MacroArgs, s)
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if !lp.Consume(",") {
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break
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}
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}
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return in, true, nil
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}
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a.FixLabel = a.DefaultFixLabel
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a.IsNewParentLabel = a.DefaultIsNewParentLabel
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return a
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}
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