mirror of https://git.sr.ht/~michalr/go-satel
25 lines
450 B
Go
25 lines
450 B
Go
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package satel
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import "math/bits"
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const seed uint16 = 0x147A
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func frame(data ...byte) []byte {
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f := append([]byte{0xFE, 0xFE}, data...)
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f = append(f, crc(data)...)
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return append(f, 0xFE, 0x0D)
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}
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func crc(data []byte) []byte {
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c := seed
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for _, b := range data {
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c = update(c, b)
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}
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return []byte{byte(c >> 8), byte(c & 0xFF)}
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}
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func update(c uint16, b byte) uint16 {
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c = bits.RotateLeft16(c, 1)
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c ^= 0xFFFF
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return c + c>>8 + uint16(b)
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}
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