wasmer_runtime_core_near/
units.rs

1//! This module provides common WebAssembly units like [`Pages`] and conversion functions into
2//! other units.
3use crate::error::PageError;
4use borsh::{BorshDeserialize, BorshSerialize};
5use std::{
6    fmt,
7    ops::{Add, Sub},
8};
9
10/// The page size in bytes of a wasm page.
11pub const WASM_PAGE_SIZE: usize = 65_536;
12/// The max number of wasm pages allowed.
13pub const WASM_MAX_PAGES: usize = 65_536;
14// From emscripten resize_heap implementation
15/// The minimum number of wasm pages allowed.
16pub const WASM_MIN_PAGES: usize = 256;
17
18/// Units of WebAssembly pages (as specified to be 65,536 bytes).
19#[derive(
20    Serialize,
21    Deserialize,
22    Copy,
23    Clone,
24    PartialEq,
25    Eq,
26    PartialOrd,
27    Ord,
28    BorshSerialize,
29    BorshDeserialize,
30)]
31pub struct Pages(pub u32);
32
33impl Pages {
34    /// Checked add of Pages to Pages.
35    pub fn checked_add(self, rhs: Pages) -> Result<Pages, PageError> {
36        let added = (self.0 as usize) + (rhs.0 as usize);
37        if added <= WASM_MAX_PAGES {
38            Ok(Pages(added as u32))
39        } else {
40            Err(PageError::ExceededMaxPages(
41                self.0 as usize,
42                rhs.0 as usize,
43                added,
44            ))
45        }
46    }
47
48    /// Calculate number of bytes from pages.
49    pub fn bytes(self) -> Bytes {
50        self.into()
51    }
52}
53
54impl fmt::Debug for Pages {
55    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
56        write!(f, "{} pages", self.0)
57    }
58}
59
60impl From<u32> for Pages {
61    fn from(other: u32) -> Self {
62        Pages(other)
63    }
64}
65
66/// Units of WebAssembly memory in terms of 8-bit bytes.
67#[derive(Serialize, Deserialize, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
68pub struct Bytes(pub usize);
69
70impl fmt::Debug for Bytes {
71    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
72        write!(f, "{} bytes", self.0)
73    }
74}
75
76impl From<Pages> for Bytes {
77    fn from(pages: Pages) -> Bytes {
78        Bytes((pages.0 as usize) * WASM_PAGE_SIZE)
79    }
80}
81
82impl From<usize> for Bytes {
83    fn from(other: usize) -> Self {
84        Bytes(other)
85    }
86}
87
88impl<T> Sub<T> for Pages
89where
90    T: Into<Pages>,
91{
92    type Output = Pages;
93    fn sub(self, rhs: T) -> Pages {
94        Pages(self.0 - rhs.into().0)
95    }
96}
97
98impl<T> Add<T> for Pages
99where
100    T: Into<Pages>,
101{
102    type Output = Pages;
103    fn add(self, rhs: T) -> Pages {
104        Pages(self.0 + rhs.into().0)
105    }
106}
107
108impl From<Bytes> for Pages {
109    fn from(bytes: Bytes) -> Pages {
110        Pages((bytes.0 / WASM_PAGE_SIZE) as u32)
111    }
112}
113
114impl<T> Sub<T> for Bytes
115where
116    T: Into<Bytes>,
117{
118    type Output = Bytes;
119    fn sub(self, rhs: T) -> Bytes {
120        Bytes(self.0 - rhs.into().0)
121    }
122}
123
124impl<T> Add<T> for Bytes
125where
126    T: Into<Bytes>,
127{
128    type Output = Bytes;
129    fn add(self, rhs: T) -> Bytes {
130        Bytes(self.0 + rhs.into().0)
131    }
132}
wasmer_runtime_core_near/units.rs

wasmer_runtime_core_near/
units.rs
