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Implementation Decisions

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Phillip Allen Lane edited this page May 19, 2026 · 2 revisions

Fundamental Integer Types

For fundamental integer types, Castor implements the LP64 data model. Below is a list of fundamental integer types, their bit widths, their corresponding sizeof, and their range:

Integer Type Bit Width sizeof Range
char 8 1 -128 to 127
short int 16 2 -32768 to 32767
int 32 4 -2147483648 to 2147483647
long int 64 8 -9223372036854775808 to 9223372036854775807
long long int 64 8 -9223372036854775808 to 9223372036854775807
signed char 8 1 -128 to 127
signed short int 16 2 -32768 to 32767
signed int 32 4 -2147483648 to 2147483647
signed long int 64 8 -9223372036854775808 to 9223372036854775807
signed long long int 64 8 -9223372036854775808 to 9223372036854775807
unsigned char 8 1 0 to 255
unsigned short int 16 2 0 to 65535
unsigned int 32 4 0 to 4294967295
unsigned long int 64 8 0 to 18446744073709551615
unsigned long long int 64 8 0 to 18446744073709551615
wchar_t 8 1 0 to 255
char16_t 16 2 0 to 65535
char32_t 32 4 0 to 4294967295

Pointer Types

Pointer types have been implemented as unbounded, unsigned integers. This decision was made to eliminate problems with pointer overflow and out-of-memory issues in the underlying theory.

Header Types

Castor-defined replacements for system headers will occasionally define new data types. Below is a list of these data types, as well as the primitive type they alias:

Header Type Aliased Type
ptrdiff_t long long int
size_t unsigned long long int
nullptr_t decltype(nullptr)
int8_t char
int16_t short int
int32_t int
int64_t long long int
int_fast8_t int8_t
int_fast16_t int16_t
int_fast32_t int32_t
int_fast64_t int64_t
int_least8_t int8_t
int_least16_t int16_t
int_least32_t int32_t
int_least64_t int64_t
intmax_t int64_t
intptr_t int64_t
uint8_t unsigned char
uint16_t unsigned short int
uint32_t unsigned int
uint64_t unsigned long long int
uint_fast8_t uint8_t
uint_fast16_t uint16_t
uint_fast32_t uint32_t
uint_fast64_t uint64_t
uint_least8_t uint8_t
uint_least16_t uint16_t
uint_least32_t uint32_t
uint_least64_t uint64_t
uintmax_t uint64_t
uintptr_t uint64_t

Evaluation order

Function parameters are evaluated right-to-left. In the case of a member function call expression.foo(...), expression is evaluated before any of the parameters. Therefore, per the C++ standard, expression.foo(args1...).bar(args2...) evaluates expression first, then args1 right-to-left, then foo, then args2 right-to-left, then bar.

Release

This software manual is released as LLNL-SM-2018190.

This document was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor Lawrence Livermore National Security, LLC, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or Lawrence Livermore National Security, LLC. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or Lawrence Livermore National Security, LLC, and shall not be used for advertising or product endorsement purposes.

This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

This document is released as LLNL-SM-2018190.

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