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