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5889f45737
The previous functions just grabbed 62 characters and slapped quotes on the ends, but that doesn't work if we want to show strings with embedded control characters. This change replaces the simple formatter with the one used to generate assembly source code. This increases the cost of refreshing the display list, so a cache will need to be added in a future change. Converters for C64 PETSCII and C64 Screen Code have been defined. The results of changing the auto-scan encoding can now be viewed. The string operand formatter was using a single delimiter, but for the on-screen version we want open-quote and close-quote, and might want to identify some encodings with a prefix. The formatter now takes a class that defines the various parts. (It might be worth replacing the delimiter patterns recently added for single-character operands with this, so we don't have two mechanisms for very nearly the same thing.) While working on this change I remembered why there were two kinds of "reverse" in the old Merlin 32 string operand generator: what you want for assembly code is different from what you want on screen. The ReverseMode enum has been resurrected.
261 lines
10 KiB
C#
261 lines
10 KiB
C#
/*
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* Copyright 2019 faddenSoft
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System;
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using System.Diagnostics;
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namespace Asm65 {
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/// <summary>
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/// Character encoding helper methods.
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/// </summary>
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public static class CharEncoding {
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public const char UNPRINTABLE_CHAR = '\ufffd'; // Unicode REPLACEMENT CHARACTER
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/// <summary>
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/// Determines whether the byte represents a member of the character set. The
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/// specifics (e.g. printable only) are defined by the method.
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/// </summary>
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public delegate bool InclusionTest(byte val);
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/// <summary>
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/// Converts the byte to a printable character. Returns UNPRINTABLE_CHAR if the value
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/// does not map to something printable.
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/// </summary>
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/// <remarks>
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/// Yes, I'm assuming it all fits in a UTF-16 char. PETSCII has some glyphs that
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/// aren't part of the BMP, but we're targeting a variety of cross-assemblers with
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/// potentially different notions of Unicode mappings, so anything non-ASCII is
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/// getting hexified anyway.
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/// </remarks>
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public delegate char Convert(byte val);
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/// <summary>
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/// Character encoding.
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/// </summary>
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public enum Encoding {
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Unknown = 0,
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Ascii,
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HighAscii,
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C64Petscii,
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C64ScreenCode,
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}
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//
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// Plain ASCII.
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//
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// We recognize BELL, LF, and CR as control characters that may be present in
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// text strings. This allows use to generate:
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//
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// .str "hello",$0d
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//
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// instead of:
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//
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// .str "hello"
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// .dd1 $0d
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//
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public static bool IsPrintableAscii(byte val) {
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return (val >= 0x20 && val < 0x7f);
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}
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public static bool IsExtendedAscii(byte val) {
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return IsPrintableAscii(val) || val == 0x07 || val == 0x0a || val == 0x0d;
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}
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public static char ConvertAscii(byte val) {
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if (IsPrintableAscii(val)) {
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return (char)val;
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} else {
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return UNPRINTABLE_CHAR;
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}
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}
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//
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// High ASCII: plain ASCII with the high bit set.
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//
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public static bool IsPrintableHighAscii(byte val) {
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return (val >= 0xa0 && val < 0xff);
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}
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public static bool IsExtendedHighAscii(byte val) {
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return IsPrintableHighAscii(val) || val == 0x87 || val == 0x8a || val == 0x8d;
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}
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public static char ConvertHighAscii(byte val) {
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if (IsPrintableHighAscii(val)) {
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return (char)(val & 0x7f);
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} else {
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return UNPRINTABLE_CHAR;
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}
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}
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//
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// High and/or low ASCII.
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//
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public static bool IsPrintableLowOrHighAscii(byte val) {
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return IsPrintableAscii((byte)(val & 0x7f));
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}
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public static bool IsExtendedLowOrHighAscii(byte val) {
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return IsExtendedAscii((byte)(val & 0x7f));
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}
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public static char ConvertLowAndHighAscii(byte val) {
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if (IsPrintableAscii(val) || IsPrintableHighAscii(val)) {
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return (char)(val & 0x7f);
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} else {
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return UNPRINTABLE_CHAR;
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}
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}
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//
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// ATASCII (Atari 400/800)
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//
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// Substantially similar to ASCII, but with printable symbols in the control character
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// range ($00-1f). Characters $60 and $7b-7f don't correspond to ASCII symbols.
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//
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// Characters with the high bit set are shown with colors reversed.
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//
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//
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// PETSCII (C64 variant)
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//
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// Assemblers like ACME use the C64 character set 2, a/k/a shifted mode, lower case
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// mode, or text mode.
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//
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// Comparison to ASCII:
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// $00-1f: control codes, many with C64-specific meanings
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// $20-3f: same as ASCII
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// $40-5f: lower case letters (rather than upper case); backslash, caret, and underscore
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// replaced with non-ASCII symbols (though the up-arrow in place of caret is close)
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// $60-7f: upper case letters (rather than lower case); backquote, curly braces,
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// vertical bar, and tilde replaced with non-ASCII symbols
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// $80-9f: more control codes
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// $a0-bf: non-ASCII symbols
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// $c0-df: clone of $60-7f; by convention this is used for upper case, since it's
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// equal to lower case with the high bit set
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// $e0-ff: non-ASCII symbols (mostly a clone of $a0-bf)
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//
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// The printable ASCII set (glyphs in [$20,$7e]) is [$20,$5b]+$5d+[$c1,$da].
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// (Looks like the Pet had $5c=backslash, but C64 went with a \u00a3 POUND SIGN instead.)
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// Anything outside that range will get printed as hex to ensure proper conversion.
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//
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// Note for the pedantic: in ASCII-1963, up-arrow and left-arrow characters were
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// assigned to the caret and underscore values. So arguably those are "ASCII" as
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// well, unless you're sane and define ASCII more narrowly.
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//
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// Control codes that we might expect to appear in the middle of a string:
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// $05 1c 1e 1f 81 90 95 96 97 98 99 9a 9b 9c 9e 9f - set text color
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// $93 - clear
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// $12 92 - reverse on/off
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// $07 0a 0d - bell, LF, CR (note CR is favored for EOL)
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//
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// Other Commodore systems use variants on PETSCII, but the ASCII correspondence remains
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// the same -- only the non-ASCII symbols change. (On the original PET, $60-7f was a
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// duplicate of $20-3f rather than a duplicate of the upper-case letters, which might be
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// why $c0-df is preferred for upper case.)
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//
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// For full details, see the chart at https://www.aivosto.com/articles/petscii.pdf
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//
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private static bool[] sPrintablePetscii = CreatePrintablePetsciiMap();
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private static bool[] sExtendedPetscii = CreateExtendedPetsciiMap();
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private static bool[] CreatePrintablePetsciiMap() {
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bool[] map = new bool[256];
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for (int i = 0x20; i <= 0x5b; i++) {
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map[i] = true;
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}
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map[0x5d] = true;
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for (int i = 0xc1; i <= 0xda; i++) {
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map[i] = true;
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}
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return map;
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}
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private static bool[] CreateExtendedPetsciiMap() {
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bool[] map = CreatePrintablePetsciiMap();
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// control codes that we might expect to find in strings
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map[0x05] = map[0x1c] = map[0x1e] = map[0x1f] = map[0x81] = map[0x90] = map[0x95] =
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map[0x96] = map[0x97] = map[0x98] = map[0x99] = map[0x9a] = map[0x9b] =
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map[0x9c] = map[0x9e] = map[0x9f] = true;
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map[0x93] = map[0x12] = map[0x92] = true;
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map[0x07] = map[0x0a] = map[0x0d] = true;
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return map;
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}
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public static bool IsPrintableC64Petscii(byte val) {
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return sPrintablePetscii[val];
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}
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public static bool IsExtendedC64Petscii(byte val) {
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return sExtendedPetscii[val];
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}
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public static char ConvertC64Petscii(byte val) {
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if ((val >= 0x20 && val <= 0x40) || val == 0x5b || val == 0x5d) {
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return (char)val; // number/symbols, '[', ']'
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} else if (val >= 0x41 && val <= 0x5a) {
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return (char)(val + 0x20); // lower case
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} else if (val >= 0xc1 && val <= 0xda) {
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return (char)(val - 0x80); // upper case
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} else {
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Debug.Assert(!IsPrintableC64Petscii(val));
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return UNPRINTABLE_CHAR;
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}
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}
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//
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// C64 Screen Codes
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//
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// Using character set 2, which includes lower case letters.
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//
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// $00-1f: lower case letters (PETSCII $40-5f)
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// $20-3f: same as ASCII (PETSCII $20-3f)
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// $40-5f: upper case letters (PETSCII $60-7f / $c0-df)
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// $60-7f: non-ASCII symbols (PETSCII $a0-bf)
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//
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// With the high bit set, character colors are reversed. The printable ASCII set
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// is [$00,$1b]+$1d+[$20,$3f]+[$41,$5a]. By definition, only printable characters
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// are included in the set, so there are no control codes.
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//
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// For full details, see the chart at https://www.aivosto.com/articles/petscii.pdf
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//
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private static bool[] sPrintableScreenCode = CreatePrintableScreenCodeMap();
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private static bool[] CreatePrintableScreenCodeMap() {
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bool[] map = new bool[256];
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for (int i = 0x00; i <= 0x1b; i++) {
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map[i] = true;
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}
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map[0x1d] = true;
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for (int i = 0x20; i <= 0x3f; i++) {
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map[i] = true;
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}
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for (int i = 0x41; i <= 0x5a; i++) {
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map[i] = true;
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}
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return map;
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}
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public static bool IsPrintableC64ScreenCode(byte val) {
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return sPrintableScreenCode[val];
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}
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public static bool IsExtendedC64ScreenCode(byte val) {
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return sPrintableScreenCode[val];
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}
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public static char ConvertC64ScreenCode(byte val) {
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if (val == 0x00 || val == 0x1b || val == 0x1d) {
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return (char)(val + 0x40); // '@', '[', ']'
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} else if (val >= 0x01 && val <= 0x1a) {
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return (char)(val + 0x60); // lower case
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} else if (val >= 0x20 && val <= 0x3f) {
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return (char)(val); // numbers/symbols
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} else if (val >= 0x41 && val <= 0x5a) {
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return (char)(val); // upper case
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} else {
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Debug.Assert(!IsPrintableC64ScreenCode(val));
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return UNPRINTABLE_CHAR;
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}
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}
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}
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}
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