ProDOS-Utilities/prodos/basic.go

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// Copyright Terence J. Boldt (c)2021-2023
// Use of this source code is governed by an MIT
// license that can be found in the LICENSE file.
// This file provides conversion between BASIC and text
package prodos
import (
"bytes"
"errors"
"fmt"
"strconv"
"strings"
)
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var tokens = map[byte]string{
0x80: "END",
0x81: "FOR",
0x82: "NEXT",
0x83: "DATA",
0x84: "INPUT",
0x85: "DEL",
0x86: "DIM",
0x87: "READ",
0x88: "GR",
0x89: "TEXT",
0x8A: "PR#",
0x8B: "IN#",
0x8C: "CALL",
0x8D: "PLOT",
0x8E: "HLIN",
0x8F: "VLIN",
0x90: "HGR2",
0x91: "HGR",
0x92: "HCOLOR=",
0x93: "HPLOT",
0x94: "DRAW",
0x95: "XDRAW",
0x96: "HTAB",
0x97: "HOME",
0x98: "ROT=",
0x99: "SCALE=",
0x9A: "SHLOAD",
0x9B: "TRACE",
0x9C: "NOTRACE",
0x9D: "NORMAL",
0x9E: "INVERSE",
0x9F: "FLASH",
0xA0: "COLOR=",
0xA1: "POP",
0xA2: "VTAB",
0xA3: "HIMEM:",
0xA4: "LOMEM:",
0xA5: "ONERR",
0xA6: "RESUME",
0xA7: "RECALL",
0xA8: "STORE",
0xA9: "SPEED=",
0xAA: "LET",
0xAB: "GOTO",
0xAC: "RUN",
0xAD: "IF",
0xAE: "RESTORE",
0xAF: "&",
0xB0: "GOSUB",
0xB1: "RETURN",
0xB2: "REM",
0xB3: "STOP",
0xB4: "ON",
0xB5: "WAIT",
0xB6: "LOAD",
0xB7: "SAVE",
0xB8: "DEF FN",
0xB9: "POKE",
0xBA: "PRINT",
0xBB: "CONT",
0xBC: "LIST",
0xBD: "CLEAR",
0xBE: "GET",
0xBF: "NEW",
0xC0: "TAB",
0xC1: "TO",
0xC2: "FN",
0xC3: "SPC(",
0xC4: "THEN",
0xC5: "AT",
0xC6: "NOT",
0xC7: "STEP",
0xC8: "+",
0xC9: "-",
0xCA: "*",
0xCB: "/",
//0xCC: ";", // fails if this is there
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0xCD: "AND",
0xCE: "OR",
0xCF: ">",
0xD0: "=",
0xD1: "<",
0xD2: "SGN",
0xD3: "INT",
0xD4: "ABS",
0xD5: "USR",
0xD6: "FRE",
0xD7: "SCRN(",
0xD8: "PDL",
0xD9: "POS",
0xDA: "SQR",
0xDB: "RND",
0xDC: "LOG",
0xDD: "EXP",
0xDE: "COS",
0xDF: "SIN",
0xE0: "TAN",
0xE1: "ATN",
0xE2: "PEEK",
0xE3: "LEN",
0xE4: "STR$",
0xE5: "VAL",
0xE6: "ASC",
0xE7: "CHR$",
0xE8: "LEFT$",
0xE9: "RIGHT$",
0xEA: "MID$",
}
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// ConvertBasicToText converts AppleSoft BASIC to text
func ConvertBasicToText(basic []byte) string {
var builder strings.Builder
i := 0
for {
lo := basic[i]
i++
hi := basic[i]
i++
if lo == 0 && hi == 0 {
return builder.String()
}
line := int(basic[i]) + int(basic[i+1])*256
i += 2
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fmt.Fprintf(&builder, "%d ", line)
for {
t := basic[i]
if t == 0 {
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builder.WriteString("\n")
i++
break
}
if t > 127 {
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builder.WriteString(" ")
builder.WriteString(tokens[t])
builder.WriteString(" ")
} else {
builder.WriteString(string(t))
}
i++
}
}
}
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// ConvertTextToBasic converts text to AppleSoft BASIC
func ConvertTextToBasic(text string) ([]byte, error) {
// convert line endings
text = strings.Replace(text, "\r\n", "\n", -1)
text = strings.Replace(text, "\r", "\n", -1)
starting := true
parsingLineNumber := false
parsingData := false
parsingString := false
parsingRem := false
foundToken := false
currentByte := 0x0801
var lineNumberString string
basicFile := new(bytes.Buffer)
basicLine := new(bytes.Buffer)
skipChars := 0
// parse character by character
for index, c := range text {
// skip initial whitespace and look for the start of a line number
if starting {
if c == ' ' {
continue
}
if c >= '0' && c <= '9' {
starting = false
parsingLineNumber = true
} else {
return nil, errors.New("unexpected character before line number")
}
}
if skipChars > 0 && c != '\n' {
skipChars--
continue
}
// parse line number
if parsingLineNumber {
if c >= '0' && c <= '9' {
lineNumberString += string(c)
} else {
lineNumber, err := strconv.ParseUint(lineNumberString, 10, 16)
if err != nil {
return nil, err
}
basicLine.WriteByte(byte(lineNumber % 256)) // low byte
basicLine.WriteByte(byte(lineNumber / 256)) // high byte
parsingLineNumber = false
lineNumberString = ""
}
}
if !parsingLineNumber {
if c == '\n' {
starting = true
parsingLineNumber = false
parsingData = false
parsingRem = false
parsingString = false
foundToken = false
currentByte += basicLine.Len()
currentByte += 3
// write address of next line
basicFile.WriteByte(byte(currentByte % 256))
basicFile.WriteByte(byte(currentByte / 256))
// write the line
basicFile.Write(basicLine.Bytes())
basicFile.WriteByte(0x00)
basicLine.Reset()
} else if parsingData {
basicLine.WriteByte(byte(c))
} else if parsingRem {
basicLine.WriteByte(byte(c))
} else if parsingString {
basicLine.WriteByte(byte(c))
if c == '"' {
parsingString = false
}
} else if c == '"' {
parsingString = true
basicLine.WriteByte(byte(c))
} else {
if c == ' ' {
continue
}
for key, token := range tokens {
if index < len(text)-len(token) {
if text[index:index+len(token)] == token {
basicLine.WriteByte(byte(key))
skipChars = len(token)
foundToken = true
if key == 0x83 {
parsingData = true
}
if key == 0xB2 {
parsingRem = true
}
}
}
}
if foundToken {
foundToken = false
} else {
basicLine.WriteByte(byte(c))
}
}
}
}
basicFile.WriteByte(0x00)
basicFile.WriteByte(0x00)
return basicFile.Bytes(), nil
}