97c759b9d8
This flattens Memory and Table types, particularly making it a compilation error to add multiple of either. This also backfills binary encoding of Table. Signed-off-by: Adrian Cole <adrian@tetrate.io>
53 lines
1.4 KiB
Go
53 lines
1.4 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/internal/leb128"
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)
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// decodeLimitsType returns the `limitsType` (min, max) decoded with the WebAssembly 1.0 (20191205) Binary Format.
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//
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// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#limits%E2%91%A6
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func decodeLimitsType(r *bytes.Reader) (min uint32, max *uint32, err error) {
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var flag byte
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if flag, err = r.ReadByte(); err != nil {
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err = fmt.Errorf("read leading byte: %v", err)
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return
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}
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switch flag {
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case 0x00:
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min, _, err = leb128.DecodeUint32(r)
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if err != nil {
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err = fmt.Errorf("read min of limit: %v", err)
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}
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case 0x01:
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min, _, err = leb128.DecodeUint32(r)
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if err != nil {
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err = fmt.Errorf("read min of limit: %v", err)
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return
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}
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var m uint32
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if m, _, err = leb128.DecodeUint32(r); err != nil {
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err = fmt.Errorf("read max of limit: %v", err)
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} else {
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max = &m
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}
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default:
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err = fmt.Errorf("%v for limits: %#x != 0x00 or 0x01", ErrInvalidByte, flag)
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}
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return
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}
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// encodeLimitsType returns the `limitsType` (min, max) encoded in WebAssembly 1.0 (20191205) Binary Format.
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//
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// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#limits%E2%91%A6
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func encodeLimitsType(min uint32, max *uint32) []byte {
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if max == nil {
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return append(leb128.EncodeUint32(0x00), leb128.EncodeUint32(min)...)
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}
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return append(leb128.EncodeUint32(0x01), append(leb128.EncodeUint32(min), leb128.EncodeUint32(*max)...)...)
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}
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