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authorWim <wim@42.be>2022-03-20 02:20:54 +0100
committerWim <wim@42.be>2022-03-20 14:57:48 +0100
commit496d5b4ec7f5f4afae6199f928675d14d18de015 (patch)
tree3a649c80a76f0ffc33e6b3a63c0e65e892169cde /vendor/github.com/skip2/go-qrcode/reedsolomon/gf_poly.go
parent2623a412c42a81104b97ae8c81a5f66760fee4b6 (diff)
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Add whatsappmulti buildflag for whatsapp with multidevice support (whatsapp)
Diffstat (limited to 'vendor/github.com/skip2/go-qrcode/reedsolomon/gf_poly.go')
-rw-r--r--vendor/github.com/skip2/go-qrcode/reedsolomon/gf_poly.go216
1 files changed, 216 insertions, 0 deletions
diff --git a/vendor/github.com/skip2/go-qrcode/reedsolomon/gf_poly.go b/vendor/github.com/skip2/go-qrcode/reedsolomon/gf_poly.go
new file mode 100644
index 00000000..962f5454
--- /dev/null
+++ b/vendor/github.com/skip2/go-qrcode/reedsolomon/gf_poly.go
@@ -0,0 +1,216 @@
+// go-qrcode
+// Copyright 2014 Tom Harwood
+
+package reedsolomon
+
+import (
+ "fmt"
+ "log"
+
+ bitset "github.com/skip2/go-qrcode/bitset"
+)
+
+// gfPoly is a polynomial over GF(2^8).
+type gfPoly struct {
+ // The ith value is the coefficient of the ith degree of x.
+ // term[0]*(x^0) + term[1]*(x^1) + term[2]*(x^2) ...
+ term []gfElement
+}
+
+// newGFPolyFromData returns |data| as a polynomial over GF(2^8).
+//
+// Each data byte becomes the coefficient of an x term.
+//
+// For an n byte input the polynomial is:
+// data[n-1]*(x^n-1) + data[n-2]*(x^n-2) ... + data[0]*(x^0).
+func newGFPolyFromData(data *bitset.Bitset) gfPoly {
+ numTotalBytes := data.Len() / 8
+ if data.Len()%8 != 0 {
+ numTotalBytes++
+ }
+
+ result := gfPoly{term: make([]gfElement, numTotalBytes)}
+
+ i := numTotalBytes - 1
+ for j := 0; j < data.Len(); j += 8 {
+ result.term[i] = gfElement(data.ByteAt(j))
+ i--
+ }
+
+ return result
+}
+
+// newGFPolyMonomial returns term*(x^degree).
+func newGFPolyMonomial(term gfElement, degree int) gfPoly {
+ if term == gfZero {
+ return gfPoly{}
+ }
+
+ result := gfPoly{term: make([]gfElement, degree+1)}
+ result.term[degree] = term
+
+ return result
+}
+
+func (e gfPoly) data(numTerms int) []byte {
+ result := make([]byte, numTerms)
+
+ i := numTerms - len(e.term)
+ for j := len(e.term) - 1; j >= 0; j-- {
+ result[i] = byte(e.term[j])
+ i++
+ }
+
+ return result
+}
+
+// numTerms returns the number of
+func (e gfPoly) numTerms() int {
+ return len(e.term)
+}
+
+// gfPolyMultiply returns a * b.
+func gfPolyMultiply(a, b gfPoly) gfPoly {
+ numATerms := a.numTerms()
+ numBTerms := b.numTerms()
+
+ result := gfPoly{term: make([]gfElement, numATerms+numBTerms)}
+
+ for i := 0; i < numATerms; i++ {
+ for j := 0; j < numBTerms; j++ {
+ if a.term[i] != 0 && b.term[j] != 0 {
+ monomial := gfPoly{term: make([]gfElement, i+j+1)}
+ monomial.term[i+j] = gfMultiply(a.term[i], b.term[j])
+
+ result = gfPolyAdd(result, monomial)
+ }
+ }
+ }
+
+ return result.normalised()
+}
+
+// gfPolyRemainder return the remainder of numerator / denominator.
+func gfPolyRemainder(numerator, denominator gfPoly) gfPoly {
+ if denominator.equals(gfPoly{}) {
+ log.Panicln("Remainder by zero")
+ }
+
+ remainder := numerator
+
+ for remainder.numTerms() >= denominator.numTerms() {
+ degree := remainder.numTerms() - denominator.numTerms()
+ coefficient := gfDivide(remainder.term[remainder.numTerms()-1],
+ denominator.term[denominator.numTerms()-1])
+
+ divisor := gfPolyMultiply(denominator,
+ newGFPolyMonomial(coefficient, degree))
+
+ remainder = gfPolyAdd(remainder, divisor)
+ }
+
+ return remainder.normalised()
+}
+
+// gfPolyAdd returns a + b.
+func gfPolyAdd(a, b gfPoly) gfPoly {
+ numATerms := a.numTerms()
+ numBTerms := b.numTerms()
+
+ numTerms := numATerms
+ if numBTerms > numTerms {
+ numTerms = numBTerms
+ }
+
+ result := gfPoly{term: make([]gfElement, numTerms)}
+
+ for i := 0; i < numTerms; i++ {
+ switch {
+ case numATerms > i && numBTerms > i:
+ result.term[i] = gfAdd(a.term[i], b.term[i])
+ case numATerms > i:
+ result.term[i] = a.term[i]
+ default:
+ result.term[i] = b.term[i]
+ }
+ }
+
+ return result.normalised()
+}
+
+func (e gfPoly) normalised() gfPoly {
+ numTerms := e.numTerms()
+ maxNonzeroTerm := numTerms - 1
+
+ for i := numTerms - 1; i >= 0; i-- {
+ if e.term[i] != 0 {
+ break
+ }
+
+ maxNonzeroTerm = i - 1
+ }
+
+ if maxNonzeroTerm < 0 {
+ return gfPoly{}
+ } else if maxNonzeroTerm < numTerms-1 {
+ e.term = e.term[0 : maxNonzeroTerm+1]
+ }
+
+ return e
+}
+
+func (e gfPoly) string(useIndexForm bool) string {
+ var str string
+ numTerms := e.numTerms()
+
+ for i := numTerms - 1; i >= 0; i-- {
+ if e.term[i] > 0 {
+ if len(str) > 0 {
+ str += " + "
+ }
+
+ if !useIndexForm {
+ str += fmt.Sprintf("%dx^%d", e.term[i], i)
+ } else {
+ str += fmt.Sprintf("a^%dx^%d", gfLogTable[e.term[i]], i)
+ }
+ }
+ }
+
+ if len(str) == 0 {
+ str = "0"
+ }
+
+ return str
+}
+
+// equals returns true if e == other.
+func (e gfPoly) equals(other gfPoly) bool {
+ var minecPoly *gfPoly
+ var maxecPoly *gfPoly
+
+ if e.numTerms() > other.numTerms() {
+ minecPoly = &other
+ maxecPoly = &e
+ } else {
+ minecPoly = &e
+ maxecPoly = &other
+ }
+
+ numMinTerms := minecPoly.numTerms()
+ numMaxTerms := maxecPoly.numTerms()
+
+ for i := 0; i < numMinTerms; i++ {
+ if e.term[i] != other.term[i] {
+ return false
+ }
+ }
+
+ for i := numMinTerms; i < numMaxTerms; i++ {
+ if maxecPoly.term[i] != 0 {
+ return false
+ }
+ }
+
+ return true
+}