implement crypto.sha256 + some crypto cleanup

vlib/crypto/sha256/sha256block_generic.v

@@ -0,0 +1,158 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+
+// SHA256 block step.
+// This is the generic version with no architecture optimizations.
+// In its own file so that an architecture
+// optimized verision can be substituted
+
+module sha256
+
+import math.bits
+
+const (
+	_K = [
+		0x428a2f98,
+		0x71374491,
+		0xb5c0fbcf,
+		0xe9b5dba5,
+		0x3956c25b,
+		0x59f111f1,
+		0x923f82a4,
+		0xab1c5ed5,
+		0xd807aa98,
+		0x12835b01,
+		0x243185be,
+		0x550c7dc3,
+		0x72be5d74,
+		0x80deb1fe,
+		0x9bdc06a7,
+		0xc19bf174,
+		0xe49b69c1,
+		0xefbe4786,
+		0x0fc19dc6,
+		0x240ca1cc,
+		0x2de92c6f,
+		0x4a7484aa,
+		0x5cb0a9dc,
+		0x76f988da,
+		0x983e5152,
+		0xa831c66d,
+		0xb00327c8,
+		0xbf597fc7,
+		0xc6e00bf3,
+		0xd5a79147,
+		0x06ca6351,
+		0x14292967,
+		0x27b70a85,
+		0x2e1b2138,
+		0x4d2c6dfc,
+		0x53380d13,
+		0x650a7354,
+		0x766a0abb,
+		0x81c2c92e,
+		0x92722c85,
+		0xa2bfe8a1,
+		0xa81a664b,
+		0xc24b8b70,
+		0xc76c51a3,
+		0xd192e819,
+		0xd6990624,
+		0xf40e3585,
+		0x106aa070,
+		0x19a4c116,
+		0x1e376c08,
+		0x2748774c,
+		0x34b0bcb5,
+		0x391c0cb3,
+		0x4ed8aa4a,
+		0x5b9cca4f,
+		0x682e6ff3,
+		0x748f82ee,
+		0x78a5636f,
+		0x84c87814,
+		0x8cc70208,
+		0x90befffa,
+		0xa4506ceb,
+		0xbef9a3f7,
+		0xc67178f2,
+	]
+)
+
+fn block_generic(dig &Digest, p []byte) {
+	mut w := [u32(0); 64]
+	
+	mut h0 := dig.h[0]
+	mut h1 := dig.h[1]
+	mut h2 := dig.h[2]
+	mut h3 := dig.h[3]
+	mut h4 := dig.h[4]
+	mut h5 := dig.h[5]
+	mut h6 := dig.h[6]
+	mut h7 := dig.h[7]
+
+	for p.len >= Chunk {
+		// Can interlace the computation of w with the
+		// rounds below if needed for speed.
+		for i := 0; i < 16; i++ {
+			j := i * 4
+			w[i] = u32(u32(p[j])<<u32(24)) | u32(u32(p[j+1])<<u32(16)) | u32(u32(p[j+2])<<u32(8)) | u32(p[j+3])
+		}
+		for i := 16; i < 64; i++ {
+			v1 := w[i-2]
+			t1 := (bits.rotate_left_32(v1, -17)) ^ (bits.rotate_left_32(v1, -19)) ^ u32((v1 >> u32(10)))
+			v2 := w[i-15]
+			t2 := (bits.rotate_left_32(v2, -7)) ^ (bits.rotate_left_32(v2, -18)) ^ u32((v2 >> u32(3)))
+			w[i] = t1 + w[i-7] + t2 + w[i-16]
+		}
+
+		mut a := h0
+		mut b := h1
+		mut c := h2
+		mut d := h3
+		mut e := h4
+		mut f := h5
+		mut g := h6
+		mut h := h7
+
+		for i := 0; i < 64; i++ {
+			t1 := h + ((bits.rotate_left_32(e, -6)) ^ (bits.rotate_left_32(e, -11)) ^ (bits.rotate_left_32(e, -25))) + ((e & f) ^ (~e & g)) + u32(_K[i]) + w[i]
+
+			t2 := ((bits.rotate_left_32(a, -2)) ^ (bits.rotate_left_32(a, -13)) ^ (bits.rotate_left_32(a, -22))) + ((a & b) ^ (a & c) ^ (b & c))
+
+			h = g
+			g = f
+			f = e
+			e = d + t1
+			d = c
+			c = b
+			b = a
+			a = t1 + t2
+		}
+
+		h0 += a
+		h1 += b
+		h2 += c
+		h3 += d
+		h4 += e
+		h5 += f
+		h6 += g
+		h7 += h
+
+		if Chunk >= p.len {
+			p = []byte
+		} else {
+			p = p.right(Chunk)
+		}
+	}
+
+	dig.h[0] = h0
+	dig.h[1] = h1
+	dig.h[2] = h2
+	dig.h[3] = h3
+	dig.h[4] = h4
+	dig.h[5] = h5
+	dig.h[6] = h6
+	dig.h[7] = h7
+}