From ebe73ccc6c70a030ffa7c6dc2c6fac3e0f2091c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=BA=90=E6=96=87=E9=9B=A8?=
 <41315874+fumiama@users.noreply.github.com>
Date: Thu, 7 Jul 2022 00:08:32 +0800
Subject: [PATCH] fix: encode panic

---
 base14_generic.go | 69 ++++++++++++++++++++++++++++-------------------
 1 file changed, 42 insertions(+), 27 deletions(-)

diff --git a/base14_generic.go b/base14_generic.go
index 6718021..001ec94 100644
--- a/base14_generic.go
+++ b/base14_generic.go
@@ -9,7 +9,8 @@ import "encoding/binary"
 func encode(offset, outlen int, b, encd []byte) {
 	var n int
 	i := 0
-	for ; i <= len(b)-7; i += 7 {
+	if len(b) == 7 {
+		b = append(b, 0)
 		shift := binary.BigEndian.Uint64(b[i:]) >> 2
 		sum := shift
 		sum &= 0x3fff000000000000
@@ -21,37 +22,51 @@ func encode(offset, outlen int, b, encd []byte) {
 		sum |= shift & 0x0000000000003fff
 		sum += 0x4e004e004e004e00
 		binary.BigEndian.PutUint64(encd[n:], sum)
-		n += 8
-	}
-	if offset > 0 {
-		sum := 0x000000000000003f & ((uint64)(b[i]) >> 2)
-		sum |= ((uint64)(b[i]) << 14) & 0x000000000000c000
-		if offset > 1 {
-			sum |= ((uint64)(b[i+1]) << 6) & 0x0000000000003f00
-			sum |= ((uint64)(b[i+1]) << 20) & 0x0000000000300000
-			if offset > 2 {
-				sum |= ((uint64)(b[i+2]) << 12) & 0x00000000000f0000
-				sum |= ((uint64)(b[i+2]) << 28) & 0x00000000f0000000
-				if offset > 3 {
-					sum |= ((uint64)(b[i+3]) << 20) & 0x000000000f000000
-					sum |= ((uint64)(b[i+3]) << 34) & 0x0000003c00000000
-					if offset > 4 {
-						sum |= ((uint64)(b[i+4]) << 26) & 0x0000000300000000
-						sum |= ((uint64)(b[i+4]) << 42) & 0x0000fc0000000000
-						if offset > 5 {
-							sum |= ((uint64)(b[i+5]) << 34) & 0x0000030000000000
-							sum |= ((uint64)(b[i+5]) << 48) & 0x003f000000000000
+	} else {
+		for ; i <= len(b)-7; i += 7 {
+			shift := binary.BigEndian.Uint64(b[i:]) >> 2
+			sum := shift
+			sum &= 0x3fff000000000000
+			shift >>= 2
+			sum |= shift & 0x00003fff00000000
+			shift >>= 2
+			sum |= shift & 0x000000003fff0000
+			shift >>= 2
+			sum |= shift & 0x0000000000003fff
+			sum += 0x4e004e004e004e00
+			binary.BigEndian.PutUint64(encd[n:], sum)
+			n += 8
+		}
+		if offset > 0 {
+			sum := 0x000000000000003f & ((uint64)(b[i]) >> 2)
+			sum |= ((uint64)(b[i]) << 14) & 0x000000000000c000
+			if offset > 1 {
+				sum |= ((uint64)(b[i+1]) << 6) & 0x0000000000003f00
+				sum |= ((uint64)(b[i+1]) << 20) & 0x0000000000300000
+				if offset > 2 {
+					sum |= ((uint64)(b[i+2]) << 12) & 0x00000000000f0000
+					sum |= ((uint64)(b[i+2]) << 28) & 0x00000000f0000000
+					if offset > 3 {
+						sum |= ((uint64)(b[i+3]) << 20) & 0x000000000f000000
+						sum |= ((uint64)(b[i+3]) << 34) & 0x0000003c00000000
+						if offset > 4 {
+							sum |= ((uint64)(b[i+4]) << 26) & 0x0000000300000000
+							sum |= ((uint64)(b[i+4]) << 42) & 0x0000fc0000000000
+							if offset > 5 {
+								sum |= ((uint64)(b[i+5]) << 34) & 0x0000030000000000
+								sum |= ((uint64)(b[i+5]) << 48) & 0x003f000000000000
+							}
 						}
 					}
 				}
 			}
+			sum += 0x004e004e004e004e
+			var tmp [8]byte
+			binary.LittleEndian.PutUint64(tmp[:], sum)
+			copy(encd[n:], tmp[:])
+			encd[outlen-2] = '='
+			encd[outlen-1] = byte(offset)
 		}
-		sum += 0x004e004e004e004e
-		var tmp [8]byte
-		binary.LittleEndian.PutUint64(tmp[:], sum)
-		copy(encd[n:], tmp[:])
-		encd[outlen-2] = '='
-		encd[outlen-1] = byte(offset)
 	}
 }