mirror of
https://github.com/henrydcase/nobs.git
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51 lines
1.1 KiB
Go
51 lines
1.1 KiB
Go
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// +build amd64,!noasm
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package csidh
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import "math/bits"
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//go:noescape
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func mul512(a, b *fp, c uint64)
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//go:noescape
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func mul576(a *[9]uint64, b *fp, c uint64)
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//go:noescape
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func cswap512(x, y *fp, choice uint8)
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//go:noescape
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func mulBmiAsm(res, x, y *fp)
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// mulRdc performs montgomery multiplication r = x * y mod P.
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// Returned result r is already reduced and in Montgomery domain.
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func mulRdc(r, x, y *fp) {
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var t fp
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var c uint64
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if hasADXandBMI2 {
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mulBmiAsm(r, x, y)
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} else {
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mulGeneric(r, x, y)
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}
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// if p <= r < 2p then r = r-p
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t[0], c = bits.Sub64(r[0], p[0], 0)
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t[1], c = bits.Sub64(r[1], p[1], c)
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t[2], c = bits.Sub64(r[2], p[2], c)
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t[3], c = bits.Sub64(r[3], p[3], c)
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t[4], c = bits.Sub64(r[4], p[4], c)
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t[5], c = bits.Sub64(r[5], p[5], c)
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t[6], c = bits.Sub64(r[6], p[6], c)
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t[7], c = bits.Sub64(r[7], p[7], c)
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var w = 0 - c
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r[0] = ctPick64(w, r[0], t[0])
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r[1] = ctPick64(w, r[1], t[1])
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r[2] = ctPick64(w, r[2], t[2])
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r[3] = ctPick64(w, r[3], t[3])
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r[4] = ctPick64(w, r[4], t[4])
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r[5] = ctPick64(w, r[5], t[5])
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r[6] = ctPick64(w, r[6], t[6])
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r[7] = ctPick64(w, r[7], t[7])
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}
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