44 lines
1017 B
Go
44 lines
1017 B
Go
package tape
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type Tag byte; const (
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SI Tag = 0 << 5 // Small integer
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LI Tag = 1 << 5 // Large integer
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FP Tag = 2 << 5 // Floating point
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SBA Tag = 3 << 5 // Small byte array
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LBA Tag = 4 << 5 // Large byte array
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OTA Tag = 5 << 5 // One-tag array
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KTV Tag = 6 << 5 // Key-tag-value table
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TNMask Tag = 0xE0 // The entire TN bitfield
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CNMask Tag = 0x20 // The entire CN bitfield
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CNLimit Tag = 32 // All valid CNs are < CNLimit
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)
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func (tag Tag) TN() int {
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return int(tag >> 5)
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}
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func (tag Tag) CN() int {
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return int(tag & CNMask)
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}
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func (tag Tag) WithCN(cn int) Tag {
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return (tag & TNMask) | Tag(cn % 32)
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}
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func (tag Tag) Is(other Tag) bool {
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return tag.TN() == other.TN()
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}
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// BufferTag returns the appropriate tag for a buffer.
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func BufferTag(value []byte) Tag {
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return bufferLenTag(len(value))
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}
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func bufferLenTag(length int) Tag {
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if length < int(CNLimit) {
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return SBA.WithCN(length)
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} else {
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return LBA.WithCN(IntBytes(uint64(length)))
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}
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}
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