117474c477
move binary encoder to its own package Signed-off-by: Edoardo Vacchi <evacchi@users.noreply.github.com>
42 lines
1.4 KiB
Go
42 lines
1.4 KiB
Go
package binaryencoding
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import (
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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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var noValType = []byte{0}
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// encodedValTypes is a cache of size prefixed binary encoding of known val types.
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var encodedValTypes = map[wasm.ValueType][]byte{
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wasm.ValueTypeI32: {1, wasm.ValueTypeI32},
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wasm.ValueTypeI64: {1, wasm.ValueTypeI64},
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wasm.ValueTypeF32: {1, wasm.ValueTypeF32},
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wasm.ValueTypeF64: {1, wasm.ValueTypeF64},
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wasm.ValueTypeExternref: {1, wasm.ValueTypeExternref},
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wasm.ValueTypeFuncref: {1, wasm.ValueTypeFuncref},
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wasm.ValueTypeV128: {1, wasm.ValueTypeV128},
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}
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// EncodeValTypes fast paths binary encoding of common value type lengths
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func EncodeValTypes(vt []wasm.ValueType) []byte {
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// Special case nullary and parameter lengths of wasi_snapshot_preview1 to avoid excess allocations
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switch uint32(len(vt)) {
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case 0: // nullary
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return noValType
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case 1: // ex $wasi.fd_close or any result
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if encoded, ok := encodedValTypes[vt[0]]; ok {
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return encoded
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}
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case 2: // ex $wasi.environ_sizes_get
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return []byte{2, vt[0], vt[1]}
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case 4: // ex $wasi.fd_write
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return []byte{4, vt[0], vt[1], vt[2], vt[3]}
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case 9: // ex $wasi.fd_write
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return []byte{9, vt[0], vt[1], vt[2], vt[3], vt[4], vt[5], vt[6], vt[7], vt[8]}
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}
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// Slow path others until someone complains with a valid signature
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count := leb128.EncodeUint32(uint32(len(vt)))
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return append(count, vt...)
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}
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