encoder.go

Documentation: github.com/tetratelabs/wazero/internal/testing/binaryencoding

     1  package binaryencoding
     2  
     3  import (
     4  	"github.com/tetratelabs/wazero/internal/leb128"
     5  	"github.com/tetratelabs/wazero/internal/wasm"
     6  )
     7  
     8  var sizePrefixedName = []byte{4, 'n', 'a', 'm', 'e'}
     9  
    10  // EncodeModule implements wasm.EncodeModule for the WebAssembly 1.0 (20191205) Binary Format.
    11  // Note: If saving to a file, the conventional extension is wasm
    12  // See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#binary-format%E2%91%A0
    13  func EncodeModule(m *wasm.Module) (bytes []byte) {
    14  	bytes = append(Magic, version...)
    15  	if m.SectionElementCount(wasm.SectionIDType) > 0 {
    16  		bytes = append(bytes, encodeTypeSection(m.TypeSection)...)
    17  	}
    18  	if m.SectionElementCount(wasm.SectionIDImport) > 0 {
    19  		bytes = append(bytes, encodeImportSection(m.ImportSection)...)
    20  	}
    21  	if m.SectionElementCount(wasm.SectionIDFunction) > 0 {
    22  		bytes = append(bytes, EncodeFunctionSection(m.FunctionSection)...)
    23  	}
    24  	if m.SectionElementCount(wasm.SectionIDTable) > 0 {
    25  		bytes = append(bytes, encodeTableSection(m.TableSection)...)
    26  	}
    27  	if m.SectionElementCount(wasm.SectionIDMemory) > 0 {
    28  		bytes = append(bytes, encodeMemorySection(m.MemorySection)...)
    29  	}
    30  	if m.SectionElementCount(wasm.SectionIDGlobal) > 0 {
    31  		bytes = append(bytes, encodeGlobalSection(m.GlobalSection)...)
    32  	}
    33  	if m.SectionElementCount(wasm.SectionIDExport) > 0 {
    34  		bytes = append(bytes, encodeExportSection(m.ExportSection)...)
    35  	}
    36  	if m.SectionElementCount(wasm.SectionIDStart) > 0 {
    37  		bytes = append(bytes, EncodeStartSection(*m.StartSection)...)
    38  	}
    39  	if m.SectionElementCount(wasm.SectionIDElement) > 0 {
    40  		bytes = append(bytes, encodeElementSection(m.ElementSection)...)
    41  	}
    42  	if m.SectionElementCount(wasm.SectionIDCode) > 0 {
    43  		bytes = append(bytes, encodeCodeSection(m.CodeSection)...)
    44  	}
    45  	if m.SectionElementCount(wasm.SectionIDData) > 0 {
    46  		bytes = append(bytes, encodeDataSection(m.DataSection)...)
    47  	}
    48  	if dc := m.DataCountSection; dc != nil {
    49  		bytes = append(bytes, encodeSection(wasm.SectionIDDataCount, leb128.EncodeUint32(*dc))...)
    50  	}
    51  	if m.SectionElementCount(wasm.SectionIDCustom) > 0 {
    52  		// >> The name section should appear only once in a module, and only after the data section.
    53  		// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#binary-namesec
    54  		if m.NameSection != nil {
    55  			nameSection := append(sizePrefixedName, EncodeNameSectionData(m.NameSection)...)
    56  			bytes = append(bytes, encodeSection(wasm.SectionIDCustom, nameSection)...)
    57  		}
    58  		for _, custom := range m.CustomSections {
    59  			bytes = append(bytes, encodeCustomSection(custom)...)
    60  		}
    61  	}
    62  	return
    63  }
    64  
    65  func encodeCustomSection(c *wasm.CustomSection) []byte {
    66  	content := append(leb128.EncodeUint32(uint32(len(c.Name))), c.Name...)
    67  	content = append(content, c.Data...)
    68  	return encodeSection(wasm.SectionIDCustom, content)
    69  }
    70
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