SYS___MAC_EXECVE             = 415 // { int __mac_execve(char *fname, char **argv, char **envv, struct mac *mac_p); }
	SYS_SIGACTION                = 416 // { int sigaction(int sig, const struct sigaction *act, struct sigaction *oact); }
	SYS_SIGRETURN                = 417 // { int sigreturn(const struct __ucontext *sigcntxp); }

	SYS___MAC_EXECVE             = 415 // { int __mac_execve(char *fname, char **argv, char **envv, struct mac *mac_p); }
	SYS_SIGACTION                = 416 // { int sigaction(int sig, const struct sigaction *act, struct sigaction *oact); }
	SYS_SIGRETURN                = 417 // { int sigreturn( const struct __ucontext *sigcntxp); }

	SYS___MAC_EXECVE             = 415 // { int __mac_execve(char *fname, char **argv, char **envv, struct mac *mac_p); }
	SYS_SIGACTION                = 416 // { int sigaction(int sig, const struct sigaction *act, struct sigaction *oact); }
	SYS_SIGRETURN                = 417 // { int sigreturn( const struct __ucontext *sigcntxp); }

	SYS___MAC_EXECVE             = 415 // { int __mac_execve(char *fname, char **argv, char **envv, struct mac *mac_p); }
	SYS_SIGACTION                = 416 // { int sigaction(int sig, const struct sigaction *act, struct sigaction *oact); }
	SYS_SIGRETURN                = 417 // { int sigreturn(const struct __ucontext *sigcntxp); }

	SYS___MAC_EXECVE             = 415 // { int __mac_execve(char *fname, char **argv, char **envv, struct mac *mac_p); }
	SYS_SIGACTION                = 416 // { int sigaction(int sig, const struct sigaction *act, struct sigaction *oact); }
	SYS_SIGRETURN                = 417 // { int sigreturn(const struct __ucontext *sigcntxp); }

		s.next()
		return true
	case '0', '1', '2', '3', '4', '5', '6', '7':
		n, base, max = 3, 8, 255
	case 'x':
		s.next()
		n, base, max = 2, 16, 255
	case 'u':
		s.next()
		n, base, max = 4, 16, unicode.MaxRune
	case 'U':
		s.next()
		n, base, max = 8, 16, unicode.MaxRune
	default:
		msg := "unknown escape sequence"
		if s.ch < 0 {
			msg = "escape sequence not terminated"
		}

		if size == 0 {
			// Some clients add a Range header to all requests to
			// limit the size of the response. If the file is empty,
			// ignore the range header and respond with a 200 rather
			// than a 416.
			ranges = nil
			break
		}
		w.Header().Set("Content-Range", fmt.Sprintf("bytes */%d", size))
		fallthrough
	default:
		serveError(w, err.Error(), StatusRequestedRangeNotSatisfiable)
		return
	}

	// Do VCIPHERLAST on the last for each encryption
	// stream and XOR the result with the corresponding
	// value from the input block.
	VCIPHERLAST4_XOR_INPUT
	// Store the results (4*16) and update BLK_OUT by 64.
	STORE_OUTPUT_BLOCK64(BLK_OUT)
	ADD	$-64, IN_LEN		// decrement input block length
	CMP	IN_LEN, $0		// check for remaining length
	BEQ	done
block16_loop:
	CMP	IN_LEN, $16		// More input