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92 lines
1.4 KiB
Go
92 lines
1.4 KiB
Go
package dmr
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const (
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// G(x) = x^9+x^6+x^4+x^3+1
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crc9poly = 0x59
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// G(x) = x^16+x^12+x^5+1
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crc16poly = 0x1021
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crc32poly = 0x04c11db7
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)
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func crc9(crc *uint16, b uint8, bits int) {
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var v uint8 = 0x80
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for i := 0; i < 8-bits; i++ {
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v >>= 1
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}
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for i := 0; i < 8; i++ {
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xor := (*crc)&0x0100 > 0
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(*crc) <<= 1
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// Limit the number of shift registers to 9.
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*crc &= 0x01ff
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if b&v > 0 {
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(*crc)++
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}
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if xor {
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(*crc) ^= crc9poly
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}
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v >>= 1
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}
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}
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func crc9end(crc *uint16, bits int) {
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for i := 0; i < bits; i++ {
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xor := (*crc)&0x100 > 0
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(*crc) <<= 1
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// Limit the number of shift registers to 9.
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*crc &= 0x01ff
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if xor {
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(*crc) ^= crc9poly
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}
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}
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}
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func crc16(crc *uint16, b byte) {
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var v uint8 = 0x80
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for i := 0; i < 8; i++ {
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xor := ((*crc) & 0x8000) > 0
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(*crc) <<= 1
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if b&v > 0 {
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(*crc)++
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}
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if xor {
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(*crc) ^= crc16poly
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}
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v >>= 1
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}
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}
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func crc16end(crc *uint16) {
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for i := 0; i < 16; i++ {
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xor := ((*crc) & 0x8000) > 0
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(*crc) <<= 1
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if xor {
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(*crc) ^= crc16poly
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}
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}
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}
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func crc32(crc *uint32, b byte) {
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var v uint8 = 0x80
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for i := 0; i < 8; i++ {
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xor := ((*crc) & 0x80000000) > 0
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(*crc) <<= 1
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if b&v > 0 {
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(*crc)++
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}
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if xor {
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(*crc) ^= crc32poly
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}
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v >>= 1
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}
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}
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func crc32end(crc *uint32) {
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for i := 0; i < 32; i++ {
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xor := ((*crc) & 0x80000000) > 0
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(*crc) <<= 1
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if xor {
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(*crc) ^= crc32poly
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}
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}
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}
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