Understanding C

Cgo scans the Go source files that import "C" for uses of that
package, such as C.puts. It collects all such identifiers. The next
step is to determine each kind of name. In C.xxx the xxx might refer
to a type, a function, a constant, or a global variable. Cgo must
decide which.

The obvious thing for cgo to do is to process the preamble, expanding

		for j := i; j <= 5; j++ {
			for k := 0; k <= 6; k++ {
				// 0 <= i <= j <= 5; 0 <= k <= 6
				// Check that if we start with a buffer
				// of length j at offset i and ask for
				// Next(k), we get the right bytes.
				buf := NewBuffer(b[0:j])
				n, _ := buf.Read(tmp[0:i])
				if n != i {
					t.Fatalf("Read %d returned %d", i, n)
				}
				bb := buf.Next(k)
				want := k
				if want > j-i {

<code>R0&lt;&lt;16</code>
<br>
<code>R0@&gt;16</code>:
For <code>&lt;&lt;</code>, left shift <code>R0</code> by 16 bits.
The other codes are <code>-&gt;</code> (arithmetic right shift),
<code>&gt;&gt;</code> (logical right shift), and
<code>@&gt;</code> (rotate right).
</li>

<li>
<code>R0-&gt;R1</code>
<br>
<code>R0&gt;&gt;R1</code>
<br>
<code>R0&lt;&lt;R1</code>
<br>
<code>R0@&gt;R1</code>:

			}
			return value << shift
		case lex.RSH:
			p.next()
			shift := p.term()
			if int64(shift) < 0 {
				p.errorf("negative right shift count")
			}
			if int64(value) < 0 {
				p.errorf("right shift of value with high bit set")
			}
			value >>= shift
		case '&':
			p.next()
			value &= p.factor()
		default:
			return value
		}
	}
}

		}
		a[na] = s[fieldStart:i:i]
		na++
		i++
		// Skip spaces in between fields.
		for i < len(s) && asciiSpace[s[i]] != 0 {
			i++
		}
		fieldStart = i
	}
	if fieldStart < len(s) { // Last field might end at EOF.
		a[na] = s[fieldStart:len(s):len(s)]
	}
	return a
}

// FieldsFunc interprets s as a sequence of UTF-8-encoded code points.
// It splits the slice s at each run of code points c satisfying f(c) and

	print(a)
}
</pre>

<p>
the assignment to <code>a</code> is not followed by
any synchronization event, so it is not guaranteed to be
observed by any other goroutine.
In fact, an aggressive compiler might delete the entire <code>go</code> statement.
</p>

<p>
If the effects of a goroutine must be observed by another goroutine,
use a synchronization mechanism such as a lock or channel

// then writeTo uses Seek to skip past holes defined in Header.SparseHoles,
// assuming that skipped regions are filled with NULs.
// This always writes the last byte to ensure w is the right size.
//
// TODO(dsnet): Re-export this when adding sparse file support.
// See https://golang.org/issue/22735
func (tr *Reader) writeTo(w io.Writer) (int64, error) {
	if tr.err != nil {
		return 0, tr.err
	}

			return false
		}
	}
	return true
}

// It would be nice if the error messages always began with
// the standard file:line: prefix,
// but that's not where we are today.
// It might be at the beginning but it might be in the middle of the printed instruction.
var fileLineRE = regexp.MustCompile(`(?:^|\()(testdata[/\\][\da-z]+\.s:\d+)(?:$|\)|:)`)

// Same as in test/run.go
var (

	// Both frameSize and argSize must be simple integers; only frameSize
	// can be negative.
	// The "-argSize" may be missing; if so, set it to objabi.ArgsSizeUnknown.
	// Parse left to right.
	op := operands[next]
	if len(op) < 2 || op[0].ScanToken != '$' {
		p.errorf("TEXT %s: frame size must be an immediate constant", name)
		return
	}
	op = op[1:]
	negative := false