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      1 // Copyright 2009 The Go Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 // +build !386,!amd64
      6 
      7 // SHA256 block step.
      8 // In its own file so that a faster assembly or C version
      9 // can be substituted easily.
     10 
     11 package sha256
     12 
     13 var _K = []uint32{
     14 	0x428a2f98,
     15 	0x71374491,
     16 	0xb5c0fbcf,
     17 	0xe9b5dba5,
     18 	0x3956c25b,
     19 	0x59f111f1,
     20 	0x923f82a4,
     21 	0xab1c5ed5,
     22 	0xd807aa98,
     23 	0x12835b01,
     24 	0x243185be,
     25 	0x550c7dc3,
     26 	0x72be5d74,
     27 	0x80deb1fe,
     28 	0x9bdc06a7,
     29 	0xc19bf174,
     30 	0xe49b69c1,
     31 	0xefbe4786,
     32 	0x0fc19dc6,
     33 	0x240ca1cc,
     34 	0x2de92c6f,
     35 	0x4a7484aa,
     36 	0x5cb0a9dc,
     37 	0x76f988da,
     38 	0x983e5152,
     39 	0xa831c66d,
     40 	0xb00327c8,
     41 	0xbf597fc7,
     42 	0xc6e00bf3,
     43 	0xd5a79147,
     44 	0x06ca6351,
     45 	0x14292967,
     46 	0x27b70a85,
     47 	0x2e1b2138,
     48 	0x4d2c6dfc,
     49 	0x53380d13,
     50 	0x650a7354,
     51 	0x766a0abb,
     52 	0x81c2c92e,
     53 	0x92722c85,
     54 	0xa2bfe8a1,
     55 	0xa81a664b,
     56 	0xc24b8b70,
     57 	0xc76c51a3,
     58 	0xd192e819,
     59 	0xd6990624,
     60 	0xf40e3585,
     61 	0x106aa070,
     62 	0x19a4c116,
     63 	0x1e376c08,
     64 	0x2748774c,
     65 	0x34b0bcb5,
     66 	0x391c0cb3,
     67 	0x4ed8aa4a,
     68 	0x5b9cca4f,
     69 	0x682e6ff3,
     70 	0x748f82ee,
     71 	0x78a5636f,
     72 	0x84c87814,
     73 	0x8cc70208,
     74 	0x90befffa,
     75 	0xa4506ceb,
     76 	0xbef9a3f7,
     77 	0xc67178f2,
     78 }
     79 
     80 func block(dig *digest, p []byte) {
     81 	var w [64]uint32
     82 	h0, h1, h2, h3, h4, h5, h6, h7 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7]
     83 	for len(p) >= chunk {
     84 		// Can interlace the computation of w with the
     85 		// rounds below if needed for speed.
     86 		for i := 0; i < 16; i++ {
     87 			j := i * 4
     88 			w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3])
     89 		}
     90 		for i := 16; i < 64; i++ {
     91 			v1 := w[i-2]
     92 			t1 := (v1>>17 | v1<<(32-17)) ^ (v1>>19 | v1<<(32-19)) ^ (v1 >> 10)
     93 			v2 := w[i-15]
     94 			t2 := (v2>>7 | v2<<(32-7)) ^ (v2>>18 | v2<<(32-18)) ^ (v2 >> 3)
     95 			w[i] = t1 + w[i-7] + t2 + w[i-16]
     96 		}
     97 
     98 		a, b, c, d, e, f, g, h := h0, h1, h2, h3, h4, h5, h6, h7
     99 
    100 		for i := 0; i < 64; i++ {
    101 			t1 := h + ((e>>6 | e<<(32-6)) ^ (e>>11 | e<<(32-11)) ^ (e>>25 | e<<(32-25))) + ((e & f) ^ (^e & g)) + _K[i] + w[i]
    102 
    103 			t2 := ((a>>2 | a<<(32-2)) ^ (a>>13 | a<<(32-13)) ^ (a>>22 | a<<(32-22))) + ((a & b) ^ (a & c) ^ (b & c))
    104 
    105 			h = g
    106 			g = f
    107 			f = e
    108 			e = d + t1
    109 			d = c
    110 			c = b
    111 			b = a
    112 			a = t1 + t2
    113 		}
    114 
    115 		h0 += a
    116 		h1 += b
    117 		h2 += c
    118 		h3 += d
    119 		h4 += e
    120 		h5 += f
    121 		h6 += g
    122 		h7 += h
    123 
    124 		p = p[chunk:]
    125 	}
    126 
    127 	dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7] = h0, h1, h2, h3, h4, h5, h6, h7
    128 }
    129