// nearest block edge where 0 <= n < blockSize.
func blockPadding(offset int64) (n int64) {
	return -offset & (blockSize - 1)
}

var zeroBlock block

type block [blockSize]byte

// Convert block to any number of formats.
func (b *block) toV7() *headerV7       { return (*headerV7)(b) }
func (b *block) toGNU() *headerGNU     { return (*headerGNU)(b) }

</pre>


<h2 id="Blocks">Blocks</h2>

<p>
A <i>block</i> is a possibly empty sequence of declarations and statements
within matching brace brackets.
</p>

<pre class="ebnf">
Block = "{" StatementList "}" .
StatementList = { Statement ";" } .
</pre>

<p>
In addition to explicit blocks in the source code, there are implicit blocks:
</p>

<ol>

pkg syscall (freebsd-riscv64), const SYS_CLOCK_GETCPUCLOCKID2 = 247 #53466
pkg syscall (freebsd-riscv64), const SYS_CLOCK_GETCPUCLOCKID2 ideal-int #53466
pkg syscall (freebsd-riscv64), const SYS_CLOCK_GETRES = 234 #53466
pkg syscall (freebsd-riscv64), const SYS_CLOCK_GETRES ideal-int #53466
pkg syscall (freebsd-riscv64), const SYS_CLOCK_GETTIME = 232 #53466
pkg syscall (freebsd-riscv64), const SYS_CLOCK_GETTIME ideal-int #53466

		if len(extra) < fieldSize {
			break
		}
		fieldBuf := extra.sub(fieldSize)

		switch fieldTag {
		case zip64ExtraID:
			f.zip64 = true

			// update directory values from the zip64 extra block.
			// They should only be consulted if the sizes read earlier
			// are maxed out.
			// See golang.org/issue/13367.
			if needUSize {
				needUSize = false
				if len(fieldBuf) < 8 {
					return ErrFormat

directive declares the symbol <code>runtime·profileloop</code> and the instructions
that follow form the body of the function.
The last instruction in a <code>TEXT</code> block must be some sort of jump, usually a <code>RET</code> (pseudo-)instruction.
(If it's not, the linker will append a jump-to-itself instruction; there is no fallthrough in <code>TEXTs</code>.)

			b.Write(buf[:1])
		}
	}
}

func BenchmarkBufferWriteBlock(b *testing.B) {
	block := make([]byte, 1024)
	for _, n := range []int{1 << 12, 1 << 16, 1 << 20} {
		b.Run(fmt.Sprintf("N%d", n), func(b *testing.B) {
			b.ReportAllocs()
			for i := 0; i < b.N; i++ {
				var bb Buffer
				for bb.Len() < n {
					bb.Write(block)
				}
			}
		})
	}
}

func BenchmarkBufferAppendNoCopy(b *testing.B) {

		// Write the initial GNU header.
		var blk block
		gnu := blk.toGNU()
		sparse := gnu.sparse()
		copy(gnu.realSize(), size)
		sps = populateSparseMap(sparse, sps)
		if format != FormatUnknown {
			blk.setFormat(format)
		}
		out = append(out, blk[:]...)

		// Write extended sparse blocks.
		for len(sps) > 0 {
			var blk block
			sps = populateSparseMap(blk.toSparse(), sps)

		}
		pre = cur
	}
	return true
}

// alignSparseEntries mutates src and returns dst where each fragment's
// starting offset is aligned up to the nearest block edge, and each
// ending offset is aligned down to the nearest block edge.
//
// Even though the Go tar Reader and the BSD tar utility can handle entries
// with arbitrary offsets and lengths, the GNU tar utility can only handle

pkg syscall (freebsd-arm64), const LOCK_EX = 2
pkg syscall (freebsd-arm64), const LOCK_EX ideal-int
pkg syscall (freebsd-arm64), const LOCK_NB = 4
pkg syscall (freebsd-arm64), const LOCK_NB ideal-int
pkg syscall (freebsd-arm64), const LOCK_SH = 1
pkg syscall (freebsd-arm64), const LOCK_SH ideal-int
pkg syscall (freebsd-arm64), const LOCK_UN = 8
pkg syscall (freebsd-arm64), const LOCK_UN ideal-int

pkg syscall (darwin-arm64), const LOCK_EX = 2
pkg syscall (darwin-arm64), const LOCK_EX ideal-int
pkg syscall (darwin-arm64), const LOCK_NB = 4
pkg syscall (darwin-arm64), const LOCK_NB ideal-int
pkg syscall (darwin-arm64), const LOCK_SH = 1
pkg syscall (darwin-arm64), const LOCK_SH ideal-int
pkg syscall (darwin-arm64), const LOCK_UN = 8
pkg syscall (darwin-arm64), const LOCK_UN ideal-int