// This file is part of https://github.com/racingmars/go3270/
// Copyright 2020 by Matthew R. Wilson, licensed under the MIT license. See
// LICENSE in the project root for license information.

package go3270

import (
	"fmt"
	"io"
)

// Enable go3270 library debugging by setting Debug to an io.Writer.
// Disable debugging by setting it to nil (the default value).
var Debug io.Writer

// debugf will print to the Debug io.Writer if it isn't nil.
func debugf(format string, a ...interface{}) {
	if Debug == nil {
		return
	}

	fmt.Fprintf(Debug, "dbg: ")
	fmt.Fprintf(Debug, format, a...)
}

// codes are the 3270 control character I/O codes, pre-computed as provided
// at http://www.tommysprinkle.com/mvs/P3270/iocodes.htm
var codes = []byte{0x40, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8,
	0xc9, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0xd1, 0xd2, 0xd3, 0xd4,
	0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60,
	0x61, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0x6a, 0x6b, 0x6c,
	0x6d, 0x6e, 0x6f, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
	0xf9, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f}

// decodes is the inverse of the above table; -1 is used in invalid positions
var decodes = []int{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, 10, 11, 12, 13, 14, 15, 16, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, -1, -1, -1, -1, -1, -1,
	-1, -1, 42, 43, 44, 45, 46, 47, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	58, 59, 60, 61, 62, 63, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1, 2,
	3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, -1, 17, 18, 19, 20, 21, 22,
	23, 24, 25, -1, -1, -1, -1, -1, -1, -1, -1, 34, 35, 36, 37, 38, 39, 40,
	41, -1, -1, -1, -1, -1, -1, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, -1,
	-1, -1, -1, -1}