Files
ghostty/src/terminal/charsets.zig
2025-11-19 15:17:05 -07:00

116 lines
3.2 KiB
Zig

const std = @import("std");
const build_options = @import("terminal_options");
const assert = @import("../quirks.zig").inlineAssert;
const LibEnum = @import("../lib/enum.zig").Enum;
/// The available charset slots for a terminal.
pub const Slots = LibEnum(
if (build_options.c_abi) .c else .zig,
&.{ "G0", "G1", "G2", "G3" },
);
/// The name of the active slots.
pub const ActiveSlot = LibEnum(
if (build_options.c_abi) .c else .zig,
&.{ "GL", "GR" },
);
/// The list of supported character sets and their associated tables.
pub const Charset = LibEnum(
if (build_options.c_abi) .c else .zig,
&.{ "utf8", "ascii", "british", "dec_special" },
);
/// The table for the given charset. This returns a pointer to a
/// slice that is guaranteed to be 255 chars that can be used to map
/// ASCII to the given charset.
pub inline fn table(set: Charset) []const u16 {
return switch (set) {
.british => &british,
.dec_special => &dec_special,
// utf8 is not a table, callers should double-check if the
// charset is utf8 and NOT use tables.
.utf8 => unreachable,
// recommended that callers just map ascii directly but we can
// support a table
.ascii => &ascii,
};
}
/// Just a basic c => c ascii table
const ascii = initTable();
/// https://vt100.net/docs/vt220-rm/chapter2.html
const british = british: {
var tbl = initTable();
tbl[0x23] = 0x00a3;
break :british tbl;
};
/// https://en.wikipedia.org/wiki/DEC_Special_Graphics
const dec_special = tech: {
var tbl = initTable();
tbl[0x60] = 0x25C6;
tbl[0x61] = 0x2592;
tbl[0x62] = 0x2409;
tbl[0x63] = 0x240C;
tbl[0x64] = 0x240D;
tbl[0x65] = 0x240A;
tbl[0x66] = 0x00B0;
tbl[0x67] = 0x00B1;
tbl[0x68] = 0x2424;
tbl[0x69] = 0x240B;
tbl[0x6a] = 0x2518;
tbl[0x6b] = 0x2510;
tbl[0x6c] = 0x250C;
tbl[0x6d] = 0x2514;
tbl[0x6e] = 0x253C;
tbl[0x6f] = 0x23BA;
tbl[0x70] = 0x23BB;
tbl[0x71] = 0x2500;
tbl[0x72] = 0x23BC;
tbl[0x73] = 0x23BD;
tbl[0x74] = 0x251C;
tbl[0x75] = 0x2524;
tbl[0x76] = 0x2534;
tbl[0x77] = 0x252C;
tbl[0x78] = 0x2502;
tbl[0x79] = 0x2264;
tbl[0x7a] = 0x2265;
tbl[0x7b] = 0x03C0;
tbl[0x7c] = 0x2260;
tbl[0x7d] = 0x00A3;
tbl[0x7e] = 0x00B7;
break :tech tbl;
};
/// Our table length is 256 so we can contain all ASCII chars.
const table_len = std.math.maxInt(u8) + 1;
/// Creates a table that maps ASCII to ASCII as a getting started point.
fn initTable() [table_len]u16 {
var result: [table_len]u16 = undefined;
var i: usize = 0;
while (i < table_len) : (i += 1) result[i] = @intCast(i);
assert(i == table_len);
return result;
}
test {
const testing = std.testing;
const info = @typeInfo(Charset).@"enum";
inline for (info.fields) |field| {
// utf8 has no table
if (@field(Charset, field.name) == .utf8) continue;
const tbl = table(@field(Charset, field.name));
// Yes, I could use `table_len` here, but I want to explicitly use a
// hardcoded constant so that if there are miscompilations or a comptime
// issue, we catch it.
try testing.expectEqual(@as(usize, 256), tbl.len);
}
}