87 lines
1.8 KiB
Markdown
87 lines
1.8 KiB
Markdown
# sha1
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[SHA-1](https://en.wikipedia.org/wiki/SHA-1) in `avo`.
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Compare to the [`crypto/sha1`](https://github.com/golang/go/blob/204a8f55dc2e0ac8d27a781dab0da609b98560da/src/crypto/sha1/sha1block_amd64.s#L16-L225) assembly.
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[embedmd]:# (asm.go /func main/ /^}/)
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```go
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func main() {
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TEXT("block", 0, "func(h *[5]uint32, m []byte)")
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Doc("block SHA-1 hashes the 64-byte message m into the running state h.")
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h := Mem{Base: Load(Param("h"), GP64())}
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m := Mem{Base: Load(Param("m").Base(), GP64())}
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// Store message values on the stack.
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w := AllocLocal(64)
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W := func(r int) Mem { return w.Offset((r % 16) * 4) }
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// Load initial hash.
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hash := [5]Register{GP32(), GP32(), GP32(), GP32(), GP32()}
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for i, r := range hash {
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MOVL(h.Offset(4*i), r)
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}
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// Initialize registers.
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a, b, c, d, e := GP32(), GP32(), GP32(), GP32(), GP32()
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for i, r := range []Register{a, b, c, d, e} {
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MOVL(hash[i], r)
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}
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// Generate round updates.
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quarter := []struct {
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F func(Register, Register, Register) Register
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K uint32
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}{
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{choose, 0x5a827999},
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{xor, 0x6ed9eba1},
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{majority, 0x8f1bbcdc},
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{xor, 0xca62c1d6},
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}
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for r := 0; r < 80; r++ {
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q := quarter[r/20]
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// Load message value.
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u := GP32()
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if r < 16 {
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MOVL(m.Offset(4*r), u)
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BSWAPL(u)
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} else {
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MOVL(W(r-3), u)
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XORL(W(r-8), u)
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XORL(W(r-14), u)
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XORL(W(r-16), u)
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ROLL(U8(1), u)
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}
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MOVL(u, W(r))
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// Compute the next state register.
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t := GP32()
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MOVL(a, t)
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ROLL(U8(5), t)
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ADDL(q.F(b, c, d), t)
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ADDL(e, t)
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ADDL(U32(q.K), t)
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ADDL(u, t)
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// Update registers.
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ROLL(Imm(30), b)
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a, b, c, d, e = t, a, b, c, d
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}
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// Final add.
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for i, r := range []Register{a, b, c, d, e} {
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ADDL(r, hash[i])
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}
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// Store results back.
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for i, r := range hash {
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MOVL(r, h.Offset(4*i))
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}
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RET()
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Generate()
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}
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```
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