34 lines
1.6 KiB
Go
34 lines
1.6 KiB
Go
package table
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import (
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"github.com/tetratelabs/wazero/api"
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"github.com/tetratelabs/wazero/internal/wasm"
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)
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// LookupFunction tries to get an api.Function from the table instance specified by `tableIndex` and `tableOffset` in the
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// given api.Module. The user of this function must be well aware of the structure of the given api.Module,
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// and the offset and table index must be valid. If this fails to find it, e.g. table is not found,
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// table offset is out of range, violates the expected types, this panics according to the same semantics as
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// call_indirect instruction: https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/exec/instructions.html#xref-syntax-instructions-syntax-instr-control-mathsf-call-indirect-x-y
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//
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// - `module` is a module instance to look up the function.
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// - `tableIndex` is the index of the table instance in the module.
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// - `tableOffset` is the offset of the lookup target in the table.
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// - `expectedParamTypes` and `expectedResultTypes` are used to check the type of the function found in the table.
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//
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// Note: the returned api.Function is always valid, i.e. not nil, if this returns without panic.
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func LookupFunction(
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module api.Module, tableIndex uint32, tableOffset uint32,
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expectedParamTypes, expectedResultTypes []api.ValueType,
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) api.Function {
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m := module.(*wasm.ModuleInstance)
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typ := &wasm.FunctionType{Params: expectedParamTypes, Results: expectedResultTypes}
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typ.CacheNumInUint64()
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typeID := m.GetFunctionTypeID(typ)
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if int(tableIndex) >= len(m.Tables) {
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panic("table index out of range")
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}
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table := m.Tables[tableIndex]
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return m.LookupFunction(table, typeID, tableOffset)
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}
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