Document acc language features.
Original text from http://www.ioccc.org/2001/bellard.hint
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+
+Supported C language subset (read joint example 'otccex.c' to have
+ an introduction to OTCC dialect):
+
+ - Expressions:
+
+ * binary operators, by decreasing priority order: '*' '/' '%',
+ '+' '-', '>>' '<<', '<' '<=' '>' '>=', '==' '!=', '&',
+ '^', '|', '=', '&&', '||'.
+
+ * '&&' and '||' have the same semantics as C : left to right
+ evaluation and early exit.
+
+ * Parenthesis are supported.
+
+ * Unary operators: '&', '*' (pointer indirection), '-'
+ (negation), '+', '!', '~', post fixed '++' and '--'.
+
+ * Pointer indirection ('*') only works with explicit cast to
+ 'char *', 'int *' or 'int (*)()' (function pointer).
+
+ * '++', '--', and unary '&' can only be used with variable
+ lvalue (left value).
+
+ * '=' can only be used with variable or '*' (pointer
+ indirection) lvalue.
+
+ * Function calls are supported with standard i386 calling
+ convention. Function pointers are supported with explicit
+ cast. Functions can be used before being declared.
+
+ - Types: only signed integer ('int') variables and functions can
+ be declared. Variables cannot be initialized in
+ declarations. Only old K&R function declarations are parsed
+ (implicit integer return value and no types on arguments).
+
+ - Any function or variable from the libc can be used because OTCC
+ uses the libc dynamic linker to resolve undefined symbols.
+
+ - Instructions: blocks ('{' '}') are supported as in C. 'if' and
+ 'else' can be used for tests. The 'while' and 'for' C constructs
+ are supported for loops. 'break' can be used to exit
+ loops. 'return' is used for the return value of a function.
+
+ - Identifiers are parsed the same way as C. Local variables are
+ handled, but there is no local name space (not a problem if
+ different names are used for local and global variables).
+
+ - Numbers can be entered in decimal, hexadecimal ('0x' or '0X'
+ prefix), or octal ('0' prefix).
+
+ - '#define' is supported without function like arguments. No macro
+ recursion is tolerated. Other preprocessor directives are
+ ignored.
+
+ - C Strings and C character constants are supported. Only '\n',
+ '\"', '\'' and '\\' escapes are recognized.
+
+ - C Comments can be used (but no C++ comments).
+
+ - No error is displayed if an incorrect program is given.
+
+ - Memory: the code, data, and symbol sizes are limited to 100KB
+ (it can be changed in the source code).
+