Lexical structure

Comments

xtc uses C-family comment syntax:

// single-line — runs to end of line
/* block — runs until the matching closer */

Identifiers

• Case-sensitive (Foo and foo are distinct).
• Start with a letter; subsequent characters may be letters, digits, or underscore.
• Reserved words may not be used as variable, class, or struct names.

Numeric literals

Three radix prefixes are recognised, and _ is silently ignored anywhere inside a numeric literal so you can group digits for readability.

u16 a = 1234;        // decimal
u16 b = $1234;       // hex
u8  c = %1010_0101;  // binary, with grouping underscore
u32 big = 16_777_216;

There is no 0x prefix; xtc inherits $ from 6502 assembler tradition.

String and character literals

Strings are double-quoted, null-terminated, but the trailing \0 is not counted in length. The recognised escape sequences are:

Escape	Means
\n	newline (CR + LF)
\r	carriage return
\t	tab
\0	end-of-string marker
\\	a literal backslash
\"	a literal " inside a string
\'	a literal ' inside a character literal

string greeting = "hello\n";

A character literal is a single character (or two characters where the first is \) inside single quotes, evaluated as a u8:

u8 tab = '\t';
u8 a   = 'A';

String literals never split across source lines.

Reserved words

The following identifiers are reserved and may not be used as names. They cover types, control flow, declaration modifiers, class machinery, and inline-asm syntax.

asm, auto, bool, break, case, class, clobbers, continue, default, delete, dealloc, do, double, else, enum, false, float, for, global, i8, i16, i32, if, in, init, inline, naked, new, pointer, protocol, register, release, retain, return, self, sizeof, static, string, struct, super, switch, true, typedef, u8, u16, u32, va_arg, va_end, va_start, void, volatile, weak, while.

The exact set is what the lexer recognises; the parser may accept more in context (e.g. function annotations like :hwStack, :irq, :vbi) which are documented on the Functions page.

Block delimiters

Both { ... } and (( ... )) introduce a block; they are interchangeable everywhere a block is accepted (function bodies, control flow, inline-asm, and so on).

void greet(void) {
    Stdio.print("hi\n");
}

void greet(void) ((
    Stdio.print("hi\n");
))

The (( )) form exists so xtc source can be typed on an Atari 8-bit keyboard, which has no { or } keys. The current toolchain is cross-compiled from desktop machines so the alternative form isn’t load-bearing today, but it preserves the option of editing or even self-hosting xtc on-target in the future. There is no semantic difference between the two forms.

Statement terminator

Statements terminate with ;. The terminator is not optional — function declarations without a body, variable declarations, and expression statements all end in ;.