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#![feature(min_specialization)]
//! A data model is the choices of bit width of integer types by each platform.
//!
//! This library is used to lookup the sizes of various C-types of a data model.
//!
//! # Examples
//!
//! ```
//! use data_models::*;
//! let model = DataModel::LP64; // e.g. Linux
//! let p = model.size_of::<Pointer>();
//! assert_eq!(p, 8);
//! ```
//!
/// 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.
///
#[derive(Debug, PartialEq)]
pub enum DataModel {
// char, short, int, long, long long, pointer, example
/// 16-bit integer and pointer (16-bit PDP-11)
IP16, // 8, --, 16, --, --, 16, 16-bit PDP-11
/// 16-bit integer and pointer and 32-bit long (32-bit PDP-11)
IP16L32, // 8, 16, 16, 32, --, 16, 32-bit PDP-11
/// 16-bit integer, and 32-bit long and pointer (m68k Mac & win16).
LP32, // 8, 16, 16, 32, 64, 32, m68k Mac; win16
/// 32-bit integer, long, and pointer (Unix and Unix-like before mid-1990s & win32).
ILP32, // 8, 16, 32, 32, 64, 32, unix < mid-1990; win32
/// 32-bit integer, long, and 64-bit pointer (windows after XP).
LLP64, // 8, 16, 32, 32, 64, 64, win >= XP
/// 32-bit integer, 64-bit long and pointer (Unix/Linux after the 1990s).
LP64, // 8, 16, 32, 64, 64, 64, unix/linux > 1990s
/// 64-bit integer, long and pointer (SPARC64 from hal/fujitsu I think).
ILP64, // 8, 16, 64, 64, 64, 64, hal/fujitsu
/// 64-bit short, integer, long and pointer (UNICOS from Cray).
SILP64, // 8, 64, 64, 64, 64, 64, cray
/// Sentinel value for unknown model.
Unknown, // I'd love to see more platforms here !
}
/// Char represents the `char` C type.
/// Smallest addressable unit of the machine.
/// It contains CHAR_BIT bits (typically 8).
///
/// Values stored in non-bit-field objects of any other integer type consist of
/// n × CHAR_BIT bits, where n is the size of an object of that type, in bytes.
///
/// # Example
/// ```
/// use data_models::*;
/// let model = DataModel::LP64;
/// let p = model.size_of::<Char>();
/// assert_eq!(p, 1);
/// ```
pub enum Char {}
/// Short represents the `short` C type.
/// It is required to be at least 16-bits.
///
/// # Example
/// ```
/// use data_models::*;
/// let model = DataModel::LP64;
/// let p = model.size_of::<Short>();
/// assert_eq!(p, 2);
/// ```
pub enum Short {}
/// Int represents the `int` C type.
/// It is required to be at least 16-bits.
///
/// # Example
/// ```
/// use data_models::*;
/// let model = DataModel::LP64;
/// let p = model.size_of::<Int>();
/// assert_eq!(p, 4);
/// ```
pub enum Int {}
/// Long represents the `long` C type.
/// It is required to be at least 32-bits.
///
/// # Example
/// ```
/// use data_models::*;
/// let model = DataModel::LP64;
/// let p = model.size_of::<Long>();
/// assert_eq!(p, 8);
/// ```
pub enum Long {}
/// LongLong represents the `long long` C type.
/// It is required to be at least 64-bits.
///
/// # Example
/// ```
/// use data_models::*;
/// let model = DataModel::LP64;
/// let p = model.size_of::<LongLong>();
/// assert_eq!(p, 8);
/// ```
pub enum LongLong {}
/// Pointer represents the `size_t` C type.
/// It is required to be at least 16-bits.
///
/// # Example
/// ```
/// use data_models::*;
/// let model = DataModel::LP64;
/// let p = model.size_of::<Pointer>();
/// assert_eq!(p, 8);
/// ```
pub enum Pointer {}
trait SizeOf<T> {
fn size_of(self) -> usize;
}
impl 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 new(int: usize, long: usize, pointer: usize) -> DataModel {
use DataModel::*;
match (int, long, pointer) {
(2, 0, 2) => IP16,
(2, 4, 2) => IP16L32,
(2, 4, 4) => LP32,
(4, 4, 4) => ILP32,
(4, 4, 8) => LLP64,
(4, 8, 8) => LP64,
(8, 8, 8) => ILP64,
_ => Unknown,
}
}
/// 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);
pub fn size_of<T>(self) -> usize {
<DataModel as SizeOf<T>>::size_of(self)
}
}
impl<T, U> SizeOf<T> for U {
default fn size_of(self) -> usize {
0
}
}
impl SizeOf<Char> for DataModel {
fn size_of(self) -> usize {
use DataModel::*;
match self {
IP16 | IP16L32 | LP32 | ILP32 | LLP64 | LP64 | ILP64 | SILP64 => 1,
Unknown => 0,
}
}
}
impl SizeOf<Short> for DataModel {
fn size_of(self) -> usize {
use DataModel::*;
match self {
IP16L32 | LP32 | ILP32 | LLP64 | LP64 | ILP64 => 2,
SILP64 => 8,
Unknown | IP16 => 0,
}
}
}
impl SizeOf<Int> for DataModel {
fn size_of(self) -> usize {
use DataModel::*;
match self {
IP16 | IP16L32 | LP32 => 2,
ILP32 | LLP64 | LP64 => 4,
ILP64 | SILP64 => 8,
Unknown => 0,
}
}
}
impl SizeOf<Long> for DataModel {
fn size_of(self) -> usize {
use DataModel::*;
match self {
IP16L32 | LP32 | ILP32 | LLP64 => 4,
LP64 | ILP64 | SILP64 => 8,
Unknown | IP16 => 0,
}
}
}
impl SizeOf<LongLong> for DataModel {
fn size_of(self) -> usize {
use DataModel::*;
match self {
LP32 | ILP32 | LLP64 | LP64 | ILP64 | SILP64 => 8,
Unknown | IP16 | IP16L32 => 0,
}
}
}
impl SizeOf<Pointer> for DataModel {
fn size_of(self) -> usize {
use DataModel::*;
match self {
IP16 | IP16L32 => 2,
LP32 | ILP32 => 4,
LLP64 | LP64 | ILP64 | SILP64 => 8,
Unknown => 0,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
macro_rules! sizeof_check {
(
$(
$model:ident: $type:path, $expect:expr
)
,
*
) => {
$(
let model = DataModel::$model;
let s = model.size_of::<$type>();
assert_eq!(s, $expect);
)*
}
}
#[test]
fn test_char() {
sizeof_check! {
IP16: Char, 1,
IP16L32: Char, 1,
LP32: Char, 1,
ILP32: Char, 1,
LLP64: Char, 1,
LP64: Char, 1,
ILP64: Char, 1,
SILP64: Char, 1,
Unknown: Char, 0
}
}
#[test]
fn test_short() {
sizeof_check! {
IP16: Short, 0,
IP16L32: Short, 2,
LP32: Short, 2,
ILP32: Short, 2,
LLP64: Short, 2,
LP64: Short, 2,
ILP64: Short, 2,
SILP64: Short, 8,
Unknown: Short, 0
}
}
#[test]
fn test_int() {
sizeof_check! {
IP16: Int, 2,
IP16L32: Int, 2,
LP32: Int, 2,
ILP32: Int, 4,
LLP64: Int, 4,
LP64: Int, 4,
ILP64: Int, 8,
SILP64: Int, 8,
Unknown: Int, 0
}
}
#[test]
fn test_long() {
sizeof_check! {
IP16: Long, 0,
IP16L32: Long, 4,
LP32: Long, 4,
ILP32: Long, 4,
LLP64: Long, 4,
LP64: Long, 8,
ILP64: Long, 8,
SILP64: Long, 8,
Unknown: Long, 0
}
}
#[test]
fn test_long_long() {
sizeof_check! {
IP16: LongLong, 0,
IP16L32: LongLong, 0,
LP32: LongLong, 8,
ILP32: LongLong, 8,
LLP64: LongLong, 8,
LP64: LongLong, 8,
ILP64: LongLong, 8,
SILP64: LongLong, 8,
Unknown: LongLong, 0
}
}
#[test]
fn test_pointer() {
sizeof_check! {
IP16: Pointer, 2,
IP16L32: Pointer, 2,
LP32: Pointer, 4,
ILP32: Pointer, 4,
LLP64: Pointer, 8,
LP64: Pointer, 8,
ILP64: Pointer, 8,
SILP64: Pointer, 8,
Unknown: Pointer, 0
}
}
#[test]
fn test_new() {
assert_eq!(DataModel::IP16, DataModel::new(2, 0, 2));
assert_eq!(DataModel::IP16L32, DataModel::new(2, 4, 2));
assert_eq!(DataModel::LP32, DataModel::new(2, 4, 4));
assert_eq!(DataModel::ILP32, DataModel::new(4, 4, 4));
assert_eq!(DataModel::LLP64, DataModel::new(4, 4, 8));
assert_eq!(DataModel::LP64, DataModel::new(4, 8, 8));
assert_eq!(DataModel::ILP64, DataModel::new(8, 8, 8));
}
}