Enum data_models::DataModel

pub enum DataModel {
    IP16,
    IP16L32,
    LP32,
    ILP32,
    LLP64,
    LP64,
    ILP64,
    SILP64,
    Unknown,
}

A data model is the choices of bit width of integer types by each platform.

Examples

use data_models::*;
let model = DataModel::LP64; // e.g. Linux
let p = model.size_of::<Pointer>();
assert_eq!(p, 8);

Background

The C standard defines five base types for integers

• char
• short
• int
• long
• long long

The standard does not specify the exact number of bits for each type. A platform or vendor-dependent data model specifies the exact bit widths.

The names of the models are conventions where the type is signified by a letter and its size; for example, ILP32 would mean (I)nteger, (L)ong, and (P)ointer are 32-bits. Although, make note, the naming scheme is not super consistent.

Four data models found wide acceptance:

• LP32 or 2/4/4 (int is 16-bit, long and pointer are 32-bit) M68k mac and Win16 API

• ILP32 or 4/4/4 (int, long, and pointer are 32-bit); Win32 API Unix and Unix-like systems (Linux, Mac OS X)

• LLP64 or 4/4/8 (int and long are 32-bit, pointer is 64-bit) Win64 API

• LP64 or 4/8/8 (int is 32-bit, long and pointer are 64-bit) Unix and Unix-like systems (Linux, Mac OS X)

References

1. J. R. Mashey. The long road to 64 bits. ACM Queue Magazine, 4(8):24–35, 1996.
2. T. Lauer. Porting to Win32: A Guide to Making Your Applications Ready for the 32-Bit Future of Windows. Springer, 1996.

Variants

IP16

16-bit integer and pointer (16-bit PDP-11)

IP16L32

16-bit integer and pointer and 32-bit long (32-bit PDP-11)

LP32

16-bit integer, and 32-bit long and pointer (m68k Mac & win16).

ILP32

32-bit integer, long, and pointer (Unix and Unix-like before mid-1990s & win32).

LLP64

32-bit integer, long, and 64-bit pointer (windows after XP).

LP64

32-bit integer, 64-bit long and pointer (Unix/Linux after the 1990s).

ILP64

64-bit integer, long and pointer (SPARC64 from hal/fujitsu I think).

SILP64

64-bit short, integer, long and pointer (UNICOS from Cray).

Unknown

Sentinel value for unknown model.

Implementations

impl DataModel

pub fn new(int: usize, long: usize, pointer: usize) -> DataModel

new tries to guess the data model from the byte size of int, long, and pointer.

Example

use data_models::*;
let model = DataModel::new(4, 8, 8); // LP64
let p = model.size_of::<Pointer>();
assert_eq!(p, 8);

pub fn size_of<T>(self) -> usize

size_of will report the size in bytes for one of the types defined in this crate.

Example

use data_models::*;
let model = DataModel::LLP64;
let p = model.size_of::<Long>();
assert_eq!(p, 4);

Trait Implementations

impl Debug for DataModel

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl PartialEq<DataModel> for DataModel

fn eq(&self, other: &DataModel) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl StructuralPartialEq for DataModel