tinywasm 0.9.0

A tiny WebAssembly interpreter
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249

use super::stack::{CallFrame, ValueStack};
use crate::{Result, interpreter::simd::Value128};
use tinywasm_types::{ExternRef, FuncRef, LocalAddr, WasmType, WasmValue};

pub(crate) type Value32 = u32;
pub(crate) type Value64 = u64;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) struct ValueRef(u32);

impl Default for ValueRef {
    fn default() -> Self {
        Self::NULL
    }
}

impl ValueRef {
    pub(crate) const NULL: Self = Self(u32::MAX);

    #[inline]
    pub(crate) const fn from_raw(raw: u32) -> Self {
        Self(raw)
    }

    #[inline]
    pub(crate) const fn from_addr(addr: Option<u32>) -> Self {
        match addr {
            Some(addr) => Self(addr),
            None => Self::NULL,
        }
    }

    #[inline]
    pub(crate) const fn addr(self) -> Option<u32> {
        if self.is_null() { None } else { Some(self.0) }
    }

    #[inline]
    pub(crate) const fn is_null(self) -> bool {
        self.0 == Self::NULL.0
    }

    #[inline]
    pub(crate) const fn raw(self) -> u32 {
        self.0
    }
}

#[allow(private_interfaces)]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
/// A untyped WebAssembly value
pub enum TinyWasmValue {
    /// A 32-bit value
    Value32(Value32),
    /// A 64-bit value
    Value64(Value64),
    /// A 128-bit value
    Value128(Value128),
    /// A reference value
    ValueRef(ValueRef),
}

impl TinyWasmValue {
    /// Converts the value to a 32-bit value (returns None if the value is not a 32-bit value)
    pub fn as_32(self) -> Option<Value32> {
        match self {
            Self::Value32(v) => Some(v),
            _ => None,
        }
    }

    /// Converts the value to a 64-bit value (returns None if the value is not a 64-bit value)
    pub fn as_64(self) -> Option<Value64> {
        match self {
            Self::Value64(v) => Some(v),
            _ => None,
        }
    }

    /// Converts the value to a 128-bit value (returns None if the value is not a 128-bit value)
    pub fn as_128(self) -> Option<Value128> {
        match self {
            Self::Value128(v) => Some(v),
            _ => None,
        }
    }

    /// Converts the value to a reference value (returns None if the value is not a reference value)
    #[allow(private_interfaces, dead_code)]
    pub fn as_ref(self) -> Option<ValueRef> {
        match self {
            Self::ValueRef(v) => Some(v),
            _ => None,
        }
    }

    /// Attaches a type to the value (panics if the size of the value is not the same as the type)
    pub fn attach_type(self, ty: WasmType) -> Option<WasmValue> {
        match (self, ty) {
            (Self::Value32(v), WasmType::I32) => Some(WasmValue::I32(v as i32)),
            (Self::Value64(v), WasmType::I64) => Some(WasmValue::I64(v as i64)),
            (Self::Value32(v), WasmType::F32) => Some(WasmValue::F32(f32::from_bits(v))),
            (Self::Value64(v), WasmType::F64) => Some(WasmValue::F64(f64::from_bits(v))),
            (Self::ValueRef(v), WasmType::RefExtern) => Some(WasmValue::RefExtern(ExternRef::from_raw(v.raw()))),
            (Self::ValueRef(v), WasmType::RefFunc) => Some(WasmValue::RefFunc(FuncRef::from_raw(v.raw()))),
            (Self::Value128(v), WasmType::V128) => Some(WasmValue::V128(v.0)),
            (_, WasmType::I32 | WasmType::F32) => None,
            (_, WasmType::I64 | WasmType::F64) => None,
            (_, WasmType::RefExtern | WasmType::RefFunc) => None,
            (_, WasmType::V128) => None,
        }
    }
}

impl From<&WasmValue> for TinyWasmValue {
    fn from(value: &WasmValue) -> Self {
        match value {
            WasmValue::I32(v) => Self::Value32(*v as u32),
            WasmValue::I64(v) => Self::Value64(*v as u64),
            WasmValue::F32(v) => Self::Value32(v.to_bits()),
            WasmValue::F64(v) => Self::Value64(v.to_bits()),
            WasmValue::RefExtern(v) => Self::ValueRef(ValueRef::from_addr(v.addr())),
            WasmValue::RefFunc(v) => Self::ValueRef(ValueRef::from_addr(v.addr())),
            WasmValue::V128(v) => Self::Value128((*v).into()),
        }
    }
}

impl From<WasmValue> for TinyWasmValue {
    fn from(value: WasmValue) -> Self {
        Self::from(&value)
    }
}

impl From<[u8; 16]> for TinyWasmValue {
    fn from(value: [u8; 16]) -> Self {
        Self::Value128(Value128::from(value))
    }
}

mod sealed {
    #[expect(unreachable_pub)]
    pub trait Sealed {}
}

pub(crate) trait InternalValue: sealed::Sealed + Into<TinyWasmValue> + Copy + Default {
    fn stack_push(stack: &mut ValueStack, value: Self) -> Result<(), crate::Trap>;
    fn stack_pop(stack: &mut ValueStack) -> Self;
    fn stack_peek(stack: &ValueStack) -> Self;
    fn stack_select(stack: &mut ValueStack) -> Result<(), crate::Trap>;
    fn local_get(stack: &ValueStack, frame: &CallFrame, index: LocalAddr) -> Self;
    fn local_set(stack: &mut ValueStack, frame: &CallFrame, index: LocalAddr, value: Self);
    fn local_update(stack: &mut ValueStack, frame: &CallFrame, index: LocalAddr, f: impl FnOnce(Self) -> Self);
    fn local_copy(stack: &mut ValueStack, frame: &CallFrame, from: LocalAddr, to: LocalAddr);
}

macro_rules! impl_internalvalue {
    (
        $(
            $variant:ident, $stack:ident, $stack_base:ident, $outer:ty,
            |$to_value_v:ident| $to_value:expr,
            |$to_stack_v:ident| $to_stack:expr,
            |$from_stack_v:ident| $from_stack:expr
        )*
    ) => {
        $(
            impl sealed::Sealed for $outer {}

            impl From<$outer> for TinyWasmValue {
                #[inline(always)]
                fn from(value: $outer) -> Self {
                    let $to_value_v = value;
                    TinyWasmValue::$variant($to_value)
                }
            }

            impl InternalValue for $outer {
                #[inline(always)]
                fn stack_push(stack: &mut ValueStack, value: Self) -> Result<(), crate::Trap> {
                    let $to_stack_v = value;
                    stack.$stack.push($to_stack)
                }

                #[inline(always)]
                fn local_get(stack: &ValueStack, frame: &CallFrame, index: LocalAddr) -> Self {
                    let $from_stack_v = *stack.$stack.get(frame.locals_base.$stack_base as usize + index as usize);
                    $from_stack
                }

                #[inline(always)]
                fn local_set(stack: &mut ValueStack, frame: &CallFrame, index: LocalAddr, value: Self) {
                    let $to_stack_v = value;
                    let abs_index = frame.locals_base.$stack_base as usize + index as usize;
                    stack.$stack.set(abs_index, $to_stack);
                }

                #[inline(always)]
                fn local_update(stack: &mut ValueStack, frame: &CallFrame, index: LocalAddr, f: impl FnOnce(Self) -> Self) {
                    let abs_index = frame.locals_base.$stack_base as usize + index as usize;
                    let $from_stack_v = *stack.$stack.get(abs_index);
                    let $to_stack_v = f($from_stack);
                    stack.$stack.set(abs_index, $to_stack);
                }

                #[inline(always)]
                fn local_copy(stack: &mut ValueStack, frame: &CallFrame, from: LocalAddr, to: LocalAddr) {
                    let val = stack.$stack.get(frame.locals_base.$stack_base as usize + from as usize);
                    stack.$stack.set(frame.locals_base.$stack_base as usize + to as usize, *val);
                }

                #[inline(always)]
                fn stack_pop(stack: &mut ValueStack) -> Self {
                    let $from_stack_v = stack.$stack.pop();
                    $from_stack
                }

                #[inline(always)]
                fn stack_peek(stack: &ValueStack) -> Self {
                    let $from_stack_v = *stack.$stack.last();
                    $from_stack
                }

                #[inline(always)]
                fn stack_select(stack: &mut ValueStack) -> Result<(), crate::Trap> {
                    let cond = stack.stack_32.pop() as i32;
                    let val2 = stack.$stack.pop();

                    if cond == 0 {
                        Self::stack_pop(stack);
                        stack.$stack.push(val2)?;
                    }

                    Ok(())
                }
            }
        )*
    };
}

impl_internalvalue! {
    Value32,  stack_32,  s32,  u32,      |v| v,               |v| v,               |v| v
    Value64,  stack_64,  s64,  u64,      |v| v,               |v| v,               |v| v
    Value32,  stack_32,  s32,  i32,      |v| v as u32,        |v| v as u32,        |v| v as i32
    Value64,  stack_64,  s64,  i64,      |v| v as u64,        |v| v as u64,        |v| v as i64
    Value32,  stack_32,  s32,  f32,      |v| f32::to_bits(v), |v| f32::to_bits(v), |v| f32::from_bits(v)
    Value64,  stack_64,  s64,  f64,      |v| f64::to_bits(v), |v| f64::to_bits(v), |v| f64::from_bits(v)
    ValueRef, stack_32,  s32,  ValueRef, |v| v,               |v| v.raw(),         |v| ValueRef(v)
    Value128, stack_128, s128, Value128, |v| v,               |v| v,               |v| v
}