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refactor binary encoding to its own package (#1187)

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move binary encoder to its own package

Signed-off-by: Edoardo Vacchi <evacchi@users.noreply.github.com>
This commit is contained in:
Edoardo Vacchi
2023-03-03 00:21:22 +01:00
committed by GitHub
parent e2660b3f17
commit 117474c477
56 changed files with 1042 additions and 608 deletions
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77
internal/wasm/binary/names.go
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@@ -149,80 +149,3 @@ func decodeFunctionCount(r *bytes.Reader, subsectionID uint8) (uint32, error) {
}
return functionCount, nil
}
// encodeNameSectionData serializes the data for the "name" key in wasm.SectionIDCustom according to the
// standard:
//
// Note: The result can be nil because this does not encode empty subsections
//
// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#binary-namesec
func encodeNameSectionData(n *wasm.NameSection) (data []byte) {
if n.ModuleName != "" {
data = append(data, encodeNameSubsection(subsectionIDModuleName, encodeSizePrefixed([]byte(n.ModuleName)))...)
}
if fd := encodeFunctionNameData(n); len(fd) > 0 {
data = append(data, encodeNameSubsection(subsectionIDFunctionNames, fd)...)
}
if ld := encodeLocalNameData(n); len(ld) > 0 {
data = append(data, encodeNameSubsection(subsectionIDLocalNames, ld)...)
}
return
}
// encodeFunctionNameData encodes the data for the function name subsection.
// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#binary-funcnamesec
func encodeFunctionNameData(n *wasm.NameSection) []byte {
if len(n.FunctionNames) == 0 {
return nil
}
return encodeNameMap(n.FunctionNames)
}
func encodeNameMap(m wasm.NameMap) []byte {
count := uint32(len(m))
data := leb128.EncodeUint32(count)
for _, na := range m {
data = append(data, encodeNameAssoc(na)...)
}
return data
}
// encodeLocalNameData encodes the data for the local name subsection.
// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#binary-localnamesec
func encodeLocalNameData(n *wasm.NameSection) []byte {
if len(n.LocalNames) == 0 {
return nil
}
funcNameCount := uint32(len(n.LocalNames))
subsection := leb128.EncodeUint32(funcNameCount)
for _, na := range n.LocalNames {
locals := encodeNameMap(na.NameMap)
subsection = append(subsection, append(leb128.EncodeUint32(na.Index), locals...)...)
}
return subsection
}
// encodeNameSubsection returns a buffer encoding the given subsection
// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#subsections%E2%91%A0
func encodeNameSubsection(subsectionID uint8, content []byte) []byte {
contentSizeInBytes := leb128.EncodeUint32(uint32(len(content)))
result := []byte{subsectionID}
result = append(result, contentSizeInBytes...)
result = append(result, content...)
return result
}
// encodeNameAssoc encodes the index and data prefixed by their size.
// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#binary-namemap
func encodeNameAssoc(na *wasm.NameAssoc) []byte {
return append(leb128.EncodeUint32(na.Index), encodeSizePrefixed([]byte(na.Name))...)
}
// encodeSizePrefixed encodes the data prefixed by their size.
func encodeSizePrefixed(data []byte) []byte {
size := leb128.EncodeUint32(uint32(len(data)))
return append(size, data...)
}