forked from gitea/gitea
45 lines
1.1 KiB
Go
45 lines
1.1 KiB
Go
package utils
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import (
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"sync"
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)
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type ReedSolomonEncoder struct {
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gf *GaloisField
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polynomes []*GFPoly
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m *sync.Mutex
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}
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func NewReedSolomonEncoder(gf *GaloisField) *ReedSolomonEncoder {
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return &ReedSolomonEncoder{
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gf, []*GFPoly{NewGFPoly(gf, []int{1})}, new(sync.Mutex),
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}
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}
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func (rs *ReedSolomonEncoder) getPolynomial(degree int) *GFPoly {
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rs.m.Lock()
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defer rs.m.Unlock()
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if degree >= len(rs.polynomes) {
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last := rs.polynomes[len(rs.polynomes)-1]
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for d := len(rs.polynomes); d <= degree; d++ {
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next := last.Multiply(NewGFPoly(rs.gf, []int{1, rs.gf.ALogTbl[d-1+rs.gf.Base]}))
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rs.polynomes = append(rs.polynomes, next)
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last = next
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}
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}
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return rs.polynomes[degree]
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}
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func (rs *ReedSolomonEncoder) Encode(data []int, eccCount int) []int {
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generator := rs.getPolynomial(eccCount)
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info := NewGFPoly(rs.gf, data)
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info = info.MultByMonominal(eccCount, 1)
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_, remainder := info.Divide(generator)
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result := make([]int, 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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