fixed issue #5 (new error correction code)
replaced the error correction code with some code based on xzing
This commit is contained in:
Florian Sundermann
parent
37c3048240
commit
63f4aa2c46
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@ -6,53 +6,42 @@ import (
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type errorCorrection struct {
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fld *utils.GaloisField
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polynomes map[byte][]byte
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polynomes []*utils.GFPoly
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}
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var ec = newGF()
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func newGF() *errorCorrection {
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return &errorCorrection{utils.NewGaloisField(285), make(map[byte][]byte)}
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fld := utils.NewGaloisField(285)
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return &errorCorrection{fld,
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[]*utils.GFPoly{
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utils.NewGFPoly(fld, []byte{1}),
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},
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}
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}
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func (ec *errorCorrection) getPolynomial(eccc byte) []byte {
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_, ok := ec.polynomes[eccc]
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if !ok {
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if eccc == 1 {
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ec.polynomes[eccc] = []byte{0, 0}
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} else {
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b1 := ec.getPolynomial(eccc - 1)
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result := make([]byte, eccc+1)
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for x := 0; x < len(b1); x++ {
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tmp1 := (int(b1[x]) + int(eccc-1)) % 255
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if x == 0 {
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result[x] = b1[x]
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} else {
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tmp0 := int(ec.fld.ALogTbl[result[x]]) ^ int(ec.fld.ALogTbl[b1[x]])
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result[x] = byte(ec.fld.LogTbl[tmp0])
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}
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result[x+1] = byte(tmp1)
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}
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ec.polynomes[eccc] = result
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func (ec *errorCorrection) getPolynomial(degree int) *utils.GFPoly {
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if degree >= len(ec.polynomes) {
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last := ec.polynomes[len(ec.polynomes)-1]
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for d := len(ec.polynomes); d <= degree; d++ {
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next := last.Multiply(utils.NewGFPoly(ec.fld, []byte{1, byte(ec.fld.ALogTbl[d-1])}))
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ec.polynomes = append(ec.polynomes, next)
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last = next
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}
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}
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return ec.polynomes[eccc]
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return ec.polynomes[degree]
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}
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func (ec *errorCorrection) calcECC(data []byte, eccCount byte) []byte {
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tmp := make([]byte, len(data)+int(eccCount))
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copy(tmp, data)
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generator := ec.getPolynomial(eccCount)
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generator := ec.getPolynomial(int(eccCount))
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info := utils.NewGFPoly(ec.fld, data)
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info = info.MultByMonominal(int(eccCount), 1)
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for i := 0; i < len(data); i++ {
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alpha := ec.fld.LogTbl[tmp[i]]
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for j := 0; j < len(generator); j++ {
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idx := (int(alpha) + int(generator[j])) % 255
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polyJ := ec.fld.ALogTbl[idx]
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tmp[i+j] = byte(ec.fld.AddOrSub(int(tmp[i+j]), polyJ))
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}
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}
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_, remainder := info.Divide(generator)
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return tmp[len(data):]
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result := make([]byte, eccCount)
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numZero := int(eccCount) - len(remainder.Coefficients)
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copy(result[numZero:], remainder.Coefficients)
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return result
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}
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@ -18,42 +18,56 @@ func Test_LogTables(t *testing.T) {
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}
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}
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func Test_GetPolynomial(t *testing.T) {
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doTest := func(b []byte) {
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cnt := byte(len(b) - 1)
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if bytes.Compare(ec.getPolynomial(cnt), b) != 0 {
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t.Errorf("Failed getPolynomial(%d)", cnt)
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}
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}
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doTest([]byte{0, 0})
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doTest([]byte{0, 87, 229, 146, 149, 238, 102, 21})
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doTest([]byte{0, 251, 67, 46, 61, 118, 70, 64, 94, 32, 45})
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doTest([]byte{0, 183, 26, 201, 87, 210, 221, 113, 21, 46, 65, 45, 50, 238, 184, 249, 225, 102, 58, 209, 218, 109, 165, 26, 95, 184, 192, 52, 245, 35, 254, 238, 175, 172, 79, 123, 25, 122, 43, 120, 108, 215, 80, 128, 201, 235, 8, 153, 59, 101, 31, 198, 76, 31, 156})
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}
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func Test_ErrorCorrection(t *testing.T) {
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doTest := func(b []byte, ecc []byte) {
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cnt := byte(len(ecc))
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if bytes.Compare(ec.calcECC(b, cnt), ecc) != 0 {
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t.Fail()
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res := ec.calcECC(b, cnt)
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if bytes.Compare(res, ecc) != 0 {
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t.Errorf("ECC error!\nGot: %v\nExpected:%v", res, ecc)
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}
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}
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// Issue #5
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doTest([]byte{66, 196, 148, 21, 99, 19, 151, 151, 53, 149, 54, 195, 4, 133, 87, 84, 115, 85, 22, 148, 52, 71, 102, 68, 134, 182, 247, 119, 22, 68, 117, 134, 35, 4, 134, 38, 21, 84, 21, 117, 87, 164, 135, 115, 211, 208, 236, 17, 236, 17, 236, 17, 236, 17, 236}, []byte{187, 187, 171, 253, 164, 129, 104, 133, 3, 75, 87, 98, 241, 146, 138})
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data1 := []byte{16, 32, 12, 86, 97, 128, 236, 17, 236, 17, 236, 17, 236, 17, 236, 17}
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doTest(data1, []byte{140, 250})
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doTest(data1, []byte{165, 36, 212, 193, 237, 54, 199, 135, 44, 85})
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doTest(data1, []byte{227, 219, 167, 206, 127, 77, 181, 205, 203, 131, 6, 102, 62, 113, 173, 153, 69, 210, 55, 111, 146, 227, 13, 144, 249, 87, 103, 81, 30, 125, 189, 61, 142, 129, 129, 43, 148, 88, 25, 249, 37, 58, 57, 108, 91, 241, 78, 248, 226, 177, 17, 58, 59, 218, 53, 146, 96, 165, 146, 163, 198, 190, 15, 71, 117, 164, 167, 53})
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data2 := []byte{0, 0, 255, 255}
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doTest(data2, []byte{171, 81, 216, 241, 210})
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doTest(data2, []byte{12, 183, 205, 34, 73, 117, 36, 75, 237, 235})
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}
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func Test_Issue5(t *testing.T) {
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data := []byte{66, 196, 148, 21, 99, 19, 151, 151, 53, 149, 54, 195, 4, 133, 87, 84, 115, 85, 22, 148, 52, 71, 102, 68, 134, 182, 247, 119, 22, 68, 117, 134, 35, 4, 134, 38, 21, 84, 21, 117, 87, 164, 135, 115, 211, 208, 236, 17, 236, 17, 236, 17, 236, 17, 236}
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correct := []byte{187, 187, 171, 253, 164, 129, 104, 133, 3, 75, 87, 98, 241, 146, 138}
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ecc := ec.calcECC(data, byte(len(correct)))
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if bytes.Compare(ecc, correct) != 0 {
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t.Errorf("ECC error!\nGot: %v\nExpected:%v", ecc, correct)
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}
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// Other tests
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doTest([]byte{17, 168, 162, 241, 255, 205, 240, 179, 88, 101, 71, 130, 2, 54, 147, 111, 232, 58, 202, 171, 85, 22, 229, 187}, []byte{30, 142, 171, 131, 189})
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doTest([]byte{36, 153, 55, 100, 228, 252, 0, 35, 85, 7, 237, 117, 182, 73, 83, 244, 8, 64, 55, 252, 200, 250, 72, 92, 97, 125, 96}, []byte{129, 124, 218, 148, 49, 108, 68, 255, 58, 212, 56, 60, 142, 45, 216, 124, 253, 214, 206, 208, 145, 169, 43})
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doTest([]byte{250, 195, 230, 128, 31, 168, 86, 123, 244, 129, 74, 130, 222, 225, 140, 129, 114, 132, 128, 88, 96, 13, 165, 132, 116, 22, 42, 81, 219, 3, 102, 156, 69, 70, 90, 68, 7, 245, 150, 160, 252, 121, 20}, []byte{124, 23, 233, 71, 200, 211, 54, 141, 10, 23, 206, 147, 116, 35, 45, 218, 158, 193, 80, 194, 129, 147, 8, 78, 229, 112, 89, 161, 167, 203, 11, 245, 186, 187, 17, 7, 175})
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doTest([]byte{121, 234, 24, 188, 218, 238, 248, 223, 98, 124, 237, 30, 98, 12, 9, 126, 5, 160, 240, 27, 174, 60, 152, 134, 71, 122, 125, 238, 223, 91, 231, 248, 230, 152, 250, 44, 17, 149, 0, 20, 109, 188, 227, 202}, []byte{209, 71, 225, 216, 240, 127, 111, 98, 194, 133, 114, 63, 35, 167, 184, 4, 209, 211, 40, 14, 74, 37, 21, 76, 95, 206, 90, 152, 110, 64, 6, 92, 80, 255, 127, 35, 111, 25, 1, 73})
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doTest([]byte{165, 233, 141, 34, 247, 216, 35, 163, 61, 61, 81, 146, 116, 96, 113, 10, 0, 6, 148, 244, 55, 201, 17, 220, 109, 111}, []byte{93, 173, 231, 160})
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doTest([]byte{173, 242, 89, 205, 24, 33, 213, 147, 96, 189, 100, 15, 213, 67, 91, 189, 218, 127, 32, 160, 162, 99, 187, 221, 53, 121, 238, 219, 215, 176, 181, 135, 56, 71, 246, 74, 228}, []byte{194, 130, 43, 168, 223, 144, 223, 49, 5, 162, 62, 218, 50, 205, 249, 84, 188, 25, 109, 110, 49, 224, 194, 244, 83, 221, 236, 71, 197, 159, 182})
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doTest([]byte{82, 138, 221, 169, 67, 161, 132, 31, 243, 110, 83, 1, 238, 79, 255, 57, 74, 54, 123, 151, 159, 50, 250, 188, 176, 8, 221, 215, 141, 77, 16}, []byte{197, 122, 225, 65, 40, 69, 153, 100, 73, 245, 150, 213, 104, 127, 3})
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doTest([]byte{5, 206, 21, 196, 185, 120, 60, 177, 90, 251, 109, 131, 174, 199, 55, 56, 14, 171, 19, 104, 236, 218, 31, 144, 33, 249, 58, 195, 173, 145, 166, 93, 122, 171, 232, 128, 233, 116, 144, 189, 62, 230, 68, 55, 140, 56, 1, 65, 165, 158, 127}, []byte{73, 141, 230, 252, 225, 173, 251, 194, 150, 98, 141, 241, 246, 11, 16, 8, 42})
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doTest([]byte{112, 106, 43, 174, 133, 163, 192, 61, 121, 3, 200, 84, 15, 9, 3, 222, 183, 78, 153, 26, 85, 41, 5, 149, 232, 3, 233, 247, 249, 29, 15, 18, 4, 96, 9, 64, 188, 210}, []byte{16, 254, 143, 110, 63, 167, 213, 242, 95, 78, 215, 145, 231, 59, 158, 36, 149, 247, 123, 114, 247, 202, 15, 56, 229, 163, 186, 73, 82, 230, 111, 108, 111, 182, 193, 46, 116})
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doTest([]byte{208, 128, 197, 227, 124, 226, 125, 46, 253, 98, 238, 80, 229, 134, 167, 70, 101, 150, 198, 130, 185, 200, 68, 91}, []byte{229, 167, 187, 39, 92, 90, 210, 25, 206, 237, 90, 194, 206, 39, 2, 11, 78, 48, 247})
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doTest([]byte{79, 175, 255, 194, 34, 229, 234, 200, 74, 213, 100, 33, 24, 5, 133, 186, 249, 151, 46, 190, 44, 126, 184, 195, 219, 37, 11, 225, 23, 8, 59, 106, 239, 198, 146, 205, 47, 59, 63, 9, 102, 29, 60, 209, 226, 67, 126, 193, 252, 255, 206, 172, 44, 53, 137, 209, 246}, []byte{237, 8, 12, 44, 90, 243, 24, 100, 123, 216, 185, 91, 182, 60, 9, 145, 126, 254, 139, 24, 211, 150, 219, 28, 138, 197, 13, 109, 227, 31, 60, 128, 237, 181, 183, 2, 138, 232, 112, 5})
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doTest([]byte{253, 217, 8, 176, 66, 153, 249, 49, 82, 114, 184, 139, 190, 87}, []byte{28, 55, 193, 193, 179, 246, 222, 5, 95, 96, 13, 242})
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doTest([]byte{15, 65, 231, 224, 151, 167, 74, 228, 23}, []byte{200, 90, 82})
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doTest([]byte{61, 186, 61, 193, 215, 243, 84, 66, 48, 93, 108, 249, 55, 232}, []byte{0, 180, 53, 152, 134, 252, 165, 168})
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doTest([]byte{78, 68, 116, 15, 85}, []byte{36})
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doTest([]byte{122, 143}, []byte{245})
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doTest([]byte{78, 85, 143, 35}, []byte{226, 85})
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doTest([]byte{11, 188, 118, 21, 177, 224, 151, 105, 21, 245, 251, 162, 72, 175, 248, 134, 123, 251, 160, 163, 42, 57, 53, 222, 195, 49, 199, 151, 5, 236, 160, 57, 212, 241, 44, 43}, []byte{186, 106})
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doTest([]byte{157, 99, 220, 166, 63, 18, 225, 215, 71, 95, 99, 200, 218, 147, 131, 245, 222, 209, 135, 152, 82, 128, 24, 0, 100, 40, 84, 193, 205, 86, 130, 204, 235, 100, 94, 61}, []byte{41, 171, 66, 233})
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doTest([]byte{249, 34, 253, 235, 233, 104, 52, 60, 17, 13, 182, 223, 19, 91, 164, 2, 196, 29, 74, 219, 65, 23, 190, 31, 10, 241, 221, 150, 221, 118, 53, 69, 45, 90, 215, 100, 155, 102, 150, 176, 203, 39, 22, 70, 10, 238}, []byte{161, 49, 179, 149, 178, 146, 208, 144, 19, 158, 180, 152, 243, 138, 143, 243, 82, 112, 229, 10, 113, 255, 139, 246})
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doTest([]byte{39, 232, 159, 64, 242, 235, 66, 226, 100, 221, 225, 247, 139, 157, 95, 155}, []byte{41, 9, 244})
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doTest([]byte{177, 185, 131, 64, 103, 93, 134, 153, 15, 26, 0, 119, 21, 27, 174, 181, 111, 245, 214, 244, 83, 66, 24, 244, 255, 189, 133, 158, 37, 46, 199, 123, 110, 153, 61, 137, 163, 231, 129, 65, 186, 89, 219, 39, 226, 236, 199, 197, 73, 213}, []byte{37, 59, 125, 211, 249, 177, 107, 79, 107, 47, 242, 168, 49, 38, 168, 198, 199, 91, 212, 22, 107, 244})
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doTest([]byte{196, 226, 29, 110, 161, 143, 64, 169, 216, 231, 115}, []byte{253, 93, 218, 129, 37})
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doTest([]byte{133, 8, 124, 221, 36, 17, 135, 115, 149, 58, 250, 103, 241, 18, 19, 246, 191, 85, 80, 255, 93, 182, 140, 123, 206, 232, 20, 166, 216, 105, 210, 229, 249, 212, 93, 227, 75, 231, 36, 195, 166, 246, 47, 168, 35, 7, 176, 124, 44, 179, 24, 145}, []byte{78, 57, 134, 181, 215, 149, 111, 51, 172, 58, 114, 3, 140, 186, 126, 40, 190})
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doTest([]byte{245, 206, 124, 0, 15, 59, 253, 225, 155}, []byte{65, 14, 188, 213, 18, 113, 161, 16})
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doTest([]byte{20, 109, 28, 180, 48, 170, 216, 48, 140, 89, 103}, []byte{193, 147, 50, 209, 160})
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doTest([]byte{87, 198, 56, 151, 121, 37, 81, 64, 193, 24, 222, 142, 102, 74, 216, 233, 198, 197, 90, 4, 65, 14, 154, 147, 200, 252, 8, 64, 97, 150, 136, 141}, []byte{231, 190, 32, 90, 100, 40, 41, 103, 200, 200, 243, 75, 177, 7, 93, 28, 83, 47, 188, 236, 20, 95, 69, 104, 155, 102, 110, 197})
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doTest([]byte{168, 72, 2, 101, 103, 118, 218, 38, 82, 85, 62, 37, 201, 96, 255, 71, 198}, []byte{129, 33, 28, 228, 195, 120, 101, 46, 119, 126})
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doTest([]byte{130, 162, 73, 44, 165, 207, 124, 28, 17, 223, 43, 143, 81, 70, 205, 161, 143, 230, 97, 94, 228, 41, 26, 187, 69, 85, 162, 51, 168, 64, 26, 207, 245, 128}, []byte{6, 171})
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doTest([]byte{95, 28, 93, 149, 234, 89, 201, 71, 39, 197, 236, 223, 251, 190, 112, 96, 101, 53, 40, 88, 136, 141, 230, 80, 45, 73, 116, 208, 197, 91, 154, 209, 128, 214, 66, 114, 137, 204, 115, 139, 96, 211, 148, 127, 104, 194}, []byte{10, 102, 57, 95, 61, 212, 130, 71, 74, 58, 82, 115, 238, 213, 251, 184, 203, 250, 55, 186, 37, 16, 71, 247, 146, 194, 74, 208, 221, 6, 81, 172, 204, 73, 102, 40, 247, 174, 213, 37, 225, 246, 8, 58})
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doTest([]byte{207, 185, 106, 191, 87, 109, 110, 210, 54, 12, 103, 161, 228}, []byte{214, 138, 159, 195, 154, 236, 33, 243, 53, 79, 227})
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doTest([]byte{203, 43, 26, 94, 37, 123, 254, 215, 153, 193, 157, 248, 180, 249, 103, 232, 107, 17, 138, 0, 11, 240, 218, 122, 19, 103, 112, 60, 125, 100, 209, 166, 103, 81, 200, 84, 77, 100, 18, 110, 209, 225, 209, 254, 185, 116, 186, 216, 206, 36, 252, 144, 90, 247, 117, 219, 81, 160}, []byte{185, 176, 106, 253, 76, 153, 185, 211, 187, 153, 210, 31, 99, 4, 46, 145, 221, 99, 236, 19, 126, 138, 66, 26, 40, 217, 170, 217, 147})
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doTest([]byte{11, 193, 90, 52, 239, 247, 144, 99, 48, 19, 154, 6, 255, 28, 47, 41, 30, 220}, []byte{235, 165, 125, 82, 28, 116, 21, 133, 243, 222, 241, 20, 134})
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doTest([]byte{173, 151, 109, 88, 104, 65, 76, 111, 219, 237, 2, 173, 25, 84, 98, 16, 135, 157, 14, 194, 228, 86, 167, 187, 137, 245, 144, 61, 200, 76, 188, 117, 223, 172, 16, 116, 84, 1, 203, 173, 170, 32, 135, 67, 16}, []byte{150, 31, 11, 211, 82, 221, 251, 84, 254, 121, 68, 34, 211, 142, 197, 246, 138, 204, 60, 197, 210, 238, 142, 234, 187, 200, 179, 228})
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doTest([]byte{171, 185, 30, 162, 129, 205, 254, 186, 86, 239, 178, 206, 115, 177, 14, 166, 143, 48, 141, 205, 109, 67, 238, 187, 134, 210, 96, 23, 195, 206, 100, 171, 156, 8, 229, 131, 169, 169, 59, 167, 224, 241, 185, 132, 162, 50, 87, 252, 156, 122, 248, 19, 130, 31, 127}, []byte{62, 42, 216, 109, 23, 176, 255, 137, 139, 90, 7, 186, 175, 243, 160, 206, 37, 94, 157, 217, 11, 169, 126, 41, 73, 133, 212, 232, 249, 117, 70, 147, 137, 156, 43, 243, 234, 155, 94, 38, 59, 211, 218, 165, 3, 33, 231, 237, 92, 16, 128})
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doTest([]byte{98, 28, 174, 108, 231, 247, 135, 139, 6, 50, 107, 203, 138, 252, 229, 245, 230, 236, 124, 138, 105, 25, 83, 122}, []byte{97, 214, 25, 2, 14, 48, 65, 212, 241, 200, 81, 57, 176, 59, 16, 55, 20, 91, 66})
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doTest([]byte{73, 214, 80, 41, 125, 136, 126, 184, 70, 141, 140, 58, 249, 250, 49, 249, 155, 0, 236, 49, 17, 125, 18, 29}, []byte{128, 16, 47, 235, 125, 128, 97, 245, 177, 210, 219, 195})
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doTest([]byte{3, 220, 98, 73, 200, 52, 8, 107, 173, 177, 58, 221, 180, 226, 76, 210, 182, 88, 104, 171, 243, 129, 88, 112, 126, 83, 141, 50, 106, 204, 195, 51, 141, 75, 132, 161}, []byte{110, 178, 213, 174, 1, 241, 95})
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doTest([]byte{196, 88, 50, 142, 76, 128, 190, 189, 76, 9, 228, 62, 198, 186, 180, 240, 62, 130, 132, 242}, []byte{244, 89, 17, 143, 3, 180, 150, 242, 167, 214, 209, 133, 120, 213, 173, 59, 25, 158, 251})
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doTest([]byte{166, 214, 1, 225, 237, 7, 80, 104, 94, 170, 125, 184, 148, 16, 121, 101, 52, 216, 177, 192, 6, 132, 77, 44, 5, 9, 126, 156, 12, 2, 29, 99, 51, 78, 177, 92, 140, 107, 146, 183, 109, 227, 171, 57, 193, 14, 37}, []byte{245, 46, 189, 11, 202, 195, 89, 53, 215, 172, 132, 196, 145, 141, 239, 160, 242, 7, 85, 251, 193, 85})
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}
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@ -30,6 +30,10 @@ func NewGaloisField(pp int) *GaloisField {
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return result
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}
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func (gf *GaloisField) Zero() *GFPoly {
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return NewGFPoly(gf, []byte{0})
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}
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// AddOrSub add or substract two numbers
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func (gf *GaloisField) AddOrSub(a, b int) int {
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return a ^ b
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@ -52,3 +56,7 @@ func (gf *GaloisField) Divide(a, b int) int {
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}
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return gf.ALogTbl[(gf.LogTbl[a]-gf.LogTbl[b])%255]
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}
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func (gf *GaloisField) Invers(num int) int {
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return gf.ALogTbl[255-gf.LogTbl[num]]
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}
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@ -0,0 +1,103 @@
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package utils
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type GFPoly struct {
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gf *GaloisField
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Coefficients []byte
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}
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func (gp *GFPoly) Degree() int {
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return len(gp.Coefficients) - 1
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}
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func (gp *GFPoly) Zero() bool {
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return gp.Coefficients[0] == 0
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}
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// GetCoefficient returns the coefficient of x ^ degree
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func (gp *GFPoly) GetCoefficient(degree int) byte {
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return gp.Coefficients[gp.Degree()-degree]
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}
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func (gp *GFPoly) AddOrSubstract(other *GFPoly) *GFPoly {
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if gp.Zero() {
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return other
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} else if other.Zero() {
|
||||
return gp
|
||||
}
|
||||
smallCoeff := gp.Coefficients
|
||||
largeCoeff := other.Coefficients
|
||||
if len(smallCoeff) > len(largeCoeff) {
|
||||
largeCoeff, smallCoeff = smallCoeff, largeCoeff
|
||||
}
|
||||
sumDiff := make([]byte, len(largeCoeff))
|
||||
lenDiff := len(largeCoeff) - len(smallCoeff)
|
||||
copy(sumDiff, largeCoeff[:lenDiff])
|
||||
for i := lenDiff; i < len(largeCoeff); i++ {
|
||||
sumDiff[i] = byte(gp.gf.AddOrSub(int(smallCoeff[i-lenDiff]), int(largeCoeff[i])))
|
||||
}
|
||||
return NewGFPoly(gp.gf, sumDiff)
|
||||
}
|
||||
|
||||
func (gp *GFPoly) MultByMonominal(degree int, coeff byte) *GFPoly {
|
||||
if coeff == 0 {
|
||||
return gp.gf.Zero()
|
||||
}
|
||||
size := len(gp.Coefficients)
|
||||
result := make([]byte, size+degree)
|
||||
for i := 0; i < size; i++ {
|
||||
result[i] = byte(gp.gf.Multiply(int(gp.Coefficients[i]), int(coeff)))
|
||||
}
|
||||
return NewGFPoly(gp.gf, result)
|
||||
}
|
||||
|
||||
func (gp *GFPoly) Multiply(other *GFPoly) *GFPoly {
|
||||
if gp.Zero() || other.Zero() {
|
||||
return gp.gf.Zero()
|
||||
}
|
||||
aCoeff := gp.Coefficients
|
||||
aLen := len(aCoeff)
|
||||
bCoeff := other.Coefficients
|
||||
bLen := len(bCoeff)
|
||||
product := make([]byte, aLen+bLen-1)
|
||||
for i := 0; i < aLen; i++ {
|
||||
ac := int(aCoeff[i])
|
||||
for j := 0; j < bLen; j++ {
|
||||
bc := int(bCoeff[j])
|
||||
product[i+j] = byte(gp.gf.AddOrSub(int(product[i+j]), gp.gf.Multiply(ac, bc)))
|
||||
}
|
||||
}
|
||||
return NewGFPoly(gp.gf, product)
|
||||
}
|
||||
|
||||
func (gp *GFPoly) Divide(other *GFPoly) (quotient *GFPoly, remainder *GFPoly) {
|
||||
quotient = gp.gf.Zero()
|
||||
remainder = gp
|
||||
fld := gp.gf
|
||||
denomLeadTerm := other.GetCoefficient(other.Degree())
|
||||
inversDenomLeadTerm := fld.Invers(int(denomLeadTerm))
|
||||
for remainder.Degree() >= other.Degree() && !remainder.Zero() {
|
||||
degreeDiff := remainder.Degree() - other.Degree()
|
||||
scale := byte(fld.Multiply(int(remainder.GetCoefficient(remainder.Degree())), inversDenomLeadTerm))
|
||||
term := other.MultByMonominal(degreeDiff, scale)
|
||||
itQuot := NewMonominalPoly(fld, degreeDiff, scale)
|
||||
quotient = quotient.AddOrSubstract(itQuot)
|
||||
remainder = remainder.AddOrSubstract(term)
|
||||
}
|
||||
return
|
||||
}
|
||||
|
||||
func NewMonominalPoly(field *GaloisField, degree int, coeff byte) *GFPoly {
|
||||
if coeff == 0 {
|
||||
return field.Zero()
|
||||
}
|
||||
result := make([]byte, degree+1)
|
||||
result[0] = coeff
|
||||
return NewGFPoly(field, result)
|
||||
}
|
||||
|
||||
func NewGFPoly(field *GaloisField, coefficients []byte) *GFPoly {
|
||||
for len(coefficients) > 1 && coefficients[0] == 0 {
|
||||
coefficients = coefficients[1:]
|
||||
}
|
||||
return &GFPoly{field, coefficients}
|
||||
}
|
||||
Loading…
Reference in New Issue