You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: sha256block.go
    path of file: ./repos/kerkour.com/blog/2023/sha256_length_extension_attacks
    
    the code of the file until where you have to start completion: // Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// SHA256 block step.
// In its own file so that a faster assembly or C version
// can be substituted easily.

package main

import "math/bits"

var _K = []uint32{
	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,
	0
    
func block(dig *digest, p []byte) {
	var w [64]uint32
	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]
	for len(p) >= 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] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3])
		}
		for i := 16; i < 64; i++ {
			v1 := w[i-2]
			t1 := (bits.RotateLeft32(v1, -17)) ^ (bits.RotateLeft32(v1, -19)) ^ (v1 >> 10)
			v2 := w[i-15]
			t2 := (bits.RotateLeft32(v2, -7)) ^ (bits.RotateLeft32(v2, -18)) ^ (v2 >> 3)
			w[i] = t1 + w[i-7] + t2 + w[i-16]
		}

		a, b, c, d, e, f, g, h := h0, h1, h2, h3, h4, h5, h6, h7

		for i := 0; i < 64; i++ {
			t1 := h + ((bits.RotateLeft32(e, -6)) ^ (bits.RotateLeft32(e, -11)) ^ (bits.RotateLeft32(e, -25))) + ((e & f) ^ (^e & g)) + _K[i] + w[i]

			t2 := ((bits.RotateLeft32(a, -2)) ^ (bits.RotateLeft32(a, -13)) ^ (bits.RotateLeft32(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

		p = p[chunk:]
	}

	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
}