rename package enc -> hex

* Makefile (fmt): fmt lib instead of enc
* challenge/c01.go: Use lib instead of enc
* challenge/c02.go: Use lib instead of enc
* enc/b64.go -> lib/b64.go
* enc/hex.go -> lib/hex.go
* enc/xor.go -> lib/xor.go

1 files changed, 26 insertions, 0 deletions

diff --git a/lib/hex.go b/lib/hex.go
new file mode 100644
index 0000000..bf539bc
--- /dev/null
+++ b/lib/hex.go
@@ -0,0 +1,26 @@
+// Copyright © 2020 rsiddharth <s@ricketyspace.net>
+// SPDX-License-Identifier: ISC
+
+package lib
+
+// Adapted from
+// https://go.googlesource.com/go/+/refs/tags/go1.15/src/encoding/hex/hex.go#83
+func HexCharToDec(c byte) uint16 {
+	switch {
+	case '0' <= c && c <= '9':
+		return uint16(c - '0')
+	case 'a' <= c && c <= 'f':
+		return uint16(c - 'a' + 10)
+	}
+	return 0
+}
+
+func DecToHexChar(i uint16) byte {
+	switch {
+	case 0 <= i && i <= 9:
+		return byte(48 + i)
+	case 10 <= i && i <= 15:
+		return byte(97 + (i - 10))
+	}
+	return 0
+}