From a215f38d6dded1dec29767fbb47a0b5c0c0ec486 Mon Sep 17 00:00:00 2001
From: Connor Olding <cloningdonor@gmail.com>
Date: Sun, 5 Aug 2012 19:24:31 -0700
Subject: [PATCH] split crc_cycle by endianness

---
 crc32.c | 29 ++++++++++++++---------------
 crc32.h |  5 ++---
 main.c  |  9 ++++-----
 3 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/crc32.c b/crc32.c
index 015463d..94680c4 100644
--- a/crc32.c
+++ b/crc32.c
@@ -53,27 +53,26 @@ static void crc_fill_table(int big)
 	}
 }
 
-static void crc_fill_tables_once()
+void crc_be_cycle(ulong *remainder, char c)
 {
 	static char filled = 0;
-	if (crc_big_endian && !(filled & 1)) {
+	ulong byte;
+	if (!filled) {
 		crc_fill_table(1);
-		filled |= 1;
-	} else if (!crc_big_endian && !(filled & 2)) {
-		crc_fill_table(0);
-		filled |= 2;
+		filled = 1;
 	}
+	byte = crc_be_table[((*remainder) >> 24) ^ c];
+	*remainder = (((*remainder) << 8) ^ byte) & 0xFFFFFFFF;
 }
 
-void crc_cycle(ulong *remainder, char c)
+void crc_le_cycle(ulong *remainder, char c)
 {
-	crc_fill_tables_once();
-	if (crc_big_endian) {
-		const ulong byte = crc_be_table[((*remainder) >> 24) ^ c];
-		*remainder = ((*remainder) << 8) ^ byte;
-		*remainder &= 0xFFFFFFFF;
-	} else {
-		const ulong byte = crc_le_table[((*remainder) ^ c) & 0xFF];
-		*remainder = ((*remainder) >> 8) ^ byte;
+	static char filled = 0;
+	ulong byte;
+	if (!filled) {
+		crc_fill_table(0);
+		filled = 1;
 	}
+	byte = crc_le_table[((*remainder) ^ c) & 0xFF];
+	*remainder = ((*remainder) >> 8) ^ byte;
 }
diff --git a/crc32.h b/crc32.h
index b939d95..aa4dc99 100644
--- a/crc32.h
+++ b/crc32.h
@@ -5,9 +5,8 @@
  * copy of the license along with this program; see the file LICENSE.
  */
 
-int crc_big_endian;
 ulong crc_polynomial;
 
-void crc_cycle(ulong *remainder, char c);
+void crc_be_cycle(ulong *remainder, char c);
+void crc_le_cycle(ulong *remainder, char c);
 ulong crc_reflect(ulong input);
-
diff --git a/main.c b/main.c
index 0639436..7da9a78 100644
--- a/main.c
+++ b/main.c
@@ -34,6 +34,7 @@ struct string_node_s {
 static string_node *input_node = NULL;
 
 static ulong starting = 0xFFFFFFFF;
+static char big_endian = 0;
 static char print_binary = 0;
 static char xor_output = 1;
 static char reflect_output = 0;
@@ -72,7 +73,7 @@ static void handle_flag(char flag, char *(*nextarg)())
 		printf(help2);
 		exit(0);
 	case 'e':
-		crc_big_endian = 1;
+		big_endian = 1;
 		return;
 	case 'b':
 		print_binary = 1;
@@ -83,9 +84,6 @@ static void handle_flag(char flag, char *(*nextarg)())
 	case 'r':
 		reflect_output = 1;
 		return;
-	}
-
-	switch (flag) {
 	case 's':
 		next = check_next(flag, nextarg());
 		starting = strtoul(next, NULL, 0);
@@ -132,6 +130,7 @@ static FILE *open_stream(char *filename)
 static ulong cycle_file(FILE *stream)
 {
 	ulong remainder = starting;
+	void (*cycle)(ulong*, char) = (big_endian) ? crc_be_cycle : crc_le_cycle;
 
 	int i, len;
 	do {
@@ -142,7 +141,7 @@ static ulong cycle_file(FILE *stream)
 		}
 
 		for (i = 0; i < len; i++)
-			crc_cycle(&remainder, buff[i]);
+			cycle(&remainder, buff[i]);
 	} while (!feof(stream));
 
 	if (xor_output)