From d90053b1bb6620dc999f723d64aadccfbe6e0bbf Mon Sep 17 00:00:00 2001
From: siddharth <s@ricketyspace.net>
Date: Sat, 19 Jun 2021 11:47:30 -0400
Subject: lib: add PrintableAscii, AsciiScores

Extracted from challenge 19
---
 challenge/c19.go | 25 ++-----------------------
 lib/str.go       | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/challenge/c19.go b/challenge/c19.go
index 544e30b..e785898 100644
--- a/challenge/c19.go
+++ b/challenge/c19.go
@@ -52,27 +52,6 @@ func C19() {
 		"VHJhbnNmb3JtZWQgdXR0ZXJseTo=",
 		"QSB0ZXJyaWJsZSBiZWF1dHkgaXMgYm9ybi4=",
 	}
-	// ASCII characters ordered by frequency
-	// (https://mdickens.me/typing/letter_frequency.html)
-	ascii := []byte{
-		' ', 'e', 't', 'a', 'o', 'i', 'n', 's', 'r', 'h', 'l', 'd',
-		'c', 'u', 'm', 'f', 'g', 'p', 'y', 'w', 'b', ',', '.',
-		'v', 'k', '-', '"', '_', '\'', 'x', ')', '(', ';', '0', 'j',
-		'1', 'q', '=', '2', ':', 'z', '/', '*', '!', '?', '$', '3',
-		'5', '>', '{', '}', '4', '9', '[', ']', '8', '6', '7', '\\',
-		'+', '|', '&', '<', '%', '@', '#', '^', '`', '~',
-	}
-	// Key: ASCII character; Value: score
-	asciiScores := make(map[byte]int, 0)
-	for pos, a := range ascii {
-		asciiScores[a] = 255 - pos
-		// Also add the uppercase version of ascii
-		// character if it exists.
-		au := lib.ByteToUpper(a)
-		if a != au {
-			asciiScores[au] = 255 - pos
-		}
-	}
 
 	// Utility functions.
 	cipherStreamByteGroups := func(ciphers [][]byte) map[int][]byte {
@@ -91,7 +70,7 @@ func C19() {
 		po := make([][]byte, len(g)) // Potential Output block bytes
 		for i, c := range g {
 			po[i] = make([]byte, 0)
-			for _, a := range ascii {
+			for _, a := range lib.PrintableAscii {
 				o := c ^ a
 				po[i] = append(po[i], o)
 
@@ -117,7 +96,7 @@ func C19() {
 			scr := 0
 			for _, c := range g {
 				p := c ^ o
-				if s, ok := asciiScores[p]; ok {
+				if s, ok := lib.AsciiScores[p]; ok {
 					scr += s
 				}
 				if pos == 0 && lib.ByteIsUpper(p) {
diff --git a/lib/str.go b/lib/str.go
index 8db415f..ee8667f 100644
--- a/lib/str.go
+++ b/lib/str.go
@@ -3,6 +3,33 @@
 
 package lib
 
+// Key: ASCII character; Value: score
+var AsciiScores map[byte]int = make(map[byte]int, 0)
+
+// Printable ASCII characters orrdered by frequency.
+// (https://mdickens.me/typing/letter_frequency.html)
+var PrintableAscii []byte = []byte{
+	' ', 'e', 't', 'a', 'o', 'i', 'n', 's', 'r', 'h', 'l', 'd',
+	'c', 'u', 'm', 'f', 'g', 'p', 'y', 'w', 'b', ',', '.',
+	'v', 'k', '-', '"', '_', '\'', 'x', ')', '(', ';', '0', 'j',
+	'1', 'q', '=', '2', ':', 'z', '/', '*', '!', '?', '$', '3',
+	'5', '>', '{', '}', '4', '9', '[', ']', '8', '6', '7', '\\',
+	'+', '|', '&', '<', '%', '@', '#', '^', '`', '~',
+}
+
+func init() {
+	// Initialize AsciiScores
+	for pos, a := range PrintableAscii {
+		AsciiScores[a] = 255 - pos
+		// Also add the uppercase version of ascii
+		// character if it exists.
+		au := ByteToUpper(a)
+		if a != au {
+			AsciiScores[au] = 255 - pos
+		}
+	}
+}
+
 func FillStr(a string, l int) string {
 	b := ""
 	if l < 1 {
-- 
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