C/C++ Programmer's Guide (G06.27+, H06.08+, J06.03+)

Alignment Issues
Native C and C++ considers objects of integral types to exist only on word boundaries.
Consequently, it is invalid to use an odd-byte address to access such an object. On TNS/R or
TNS/E systems, the results of using an integer type extended pointer containing an odd-byte address
are undefined. The code might continue executing or trap. Therefore, it is important for you to
ensure that all extended pointers contain addresses that are even except for pointers to char.
Extended pointers are those of type long int or those of type int with the 32-bit (wide) data
model in effect, in which case an int is represented by 32 bits.
Translation Limits for Native C Compilers
Native C uses dynamic data structures, so some program components are limited by the amount
of available memory. This list indicates minimums that are guaranteed (that is, a program that
meets but does not exceed each minimum is guaranteed to compile). However, if a program
significantly exceeds one or more minimums, it is possible to run out of memory and to receive an
error message on a component whose minimum has not been reached. The limits differ for the
TNS/R and TNS/E native C compilers.
TNS/R Native C Compiler
• Compound statements, iteration control statements, and selection control statements can be
nested 15 levels.
• Conditional #include directives can be nested 8 levels.
• Arithmetic, structure, union, or incomplete type declarations can have 12 pointer, array, and
function declarators modifying them.
• A declaration can have 31 nested levels of parenthesized declarators.
• An expression can have 32 nested levels of parenthesized expressions.
• An internal identifier or macro name can have 31 significant characters.
• An external identifier can have 31 significant initial characters.
• A single translation unit can have 511 external identifiers.
• A block can have 127 identifiers declared with block scope.
• A single translation unit can have 1024 macro identifiers defined simultaneously.
• A macro definition can have 31 parameters and a macro invocation 31 arguments.
• A logical source line can have 509 characters.
• A string literal or wide string literal can have 509 characters (after string concatenation).
• An object can consist of 32767 bytes.
• A switch statement can have 257 case labels (excluding any nested switch statements).
• A single struct or union can have 127 members.
• A single enumeration can have 127 enumeration constants.
• A single structure declaration can have 15 levels of nested structure or union definitions.
TNS/E Native C Compiler
• Compound statements, iteration control statements, and selection control statements can be
nested to at least 127 levels.
• Conditional #include directives can be nested 63 levels.
• Arithmetic, structure, union, or incomplete type declarations can have at least 12 pointer,
array, and function declarators modifying them.
• A declaration can have at least 63 nested levels of parenthesized declarators.
• An expression can have at least 63 nested levels of parenthesized expressions.
Translation Limits for Native C Compilers 405