69 lines
1.9 KiB
Go
69 lines
1.9 KiB
Go
package binary
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import (
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"bytes"
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"fmt"
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"github.com/tetratelabs/wazero/api"
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"github.com/tetratelabs/wazero/internal/leb128"
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"github.com/tetratelabs/wazero/internal/wasm"
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)
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// encodeFunctionType returns the wasm.FunctionType encoded in WebAssembly 1.0 (20191205) Binary Format.
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//
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// Note: Function types are encoded by the byte 0x60 followed by the respective vectors of parameter and result types.
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// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#function-types%E2%91%A4
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func encodeFunctionType(t *wasm.FunctionType) []byte {
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// Only reached when "multi-value" is enabled because WebAssembly 1.0 (20191205) supports at most 1 result.
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data := append([]byte{0x60}, encodeValTypes(t.Params)...)
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return append(data, encodeValTypes(t.Results)...)
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}
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func decodeFunctionType(enabledFeatures api.CoreFeatures, r *bytes.Reader) (*wasm.FunctionType, error) {
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b, err := r.ReadByte()
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if err != nil {
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return nil, fmt.Errorf("read leading byte: %w", err)
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}
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if b != 0x60 {
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return nil, fmt.Errorf("%w: %#x != 0x60", ErrInvalidByte, b)
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}
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paramCount, _, err := leb128.DecodeUint32(r)
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if err != nil {
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return nil, fmt.Errorf("could not read parameter count: %w", err)
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}
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paramTypes, err := decodeValueTypes(r, paramCount)
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if err != nil {
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return nil, fmt.Errorf("could not read parameter types: %w", err)
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}
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resultCount, _, err := leb128.DecodeUint32(r)
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if err != nil {
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return nil, fmt.Errorf("could not read result count: %w", err)
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}
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// Guard >1.0 feature multi-value
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if resultCount > 1 {
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if err = enabledFeatures.RequireEnabled(api.CoreFeatureMultiValue); err != nil {
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return nil, fmt.Errorf("multiple result types invalid as %v", err)
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}
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}
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resultTypes, err := decodeValueTypes(r, resultCount)
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if err != nil {
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return nil, fmt.Errorf("could not read result types: %w", err)
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}
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ret := &wasm.FunctionType{
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Params: paramTypes,
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Results: resultTypes,
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}
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// cache the key for the function type
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_ = ret.String()
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return ret, nil
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}
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