Merge branch 'modern'

LICENSE

@@ -1,4 +1,4 @@
-Copyright (C) 2012 Connor Olding
+Copyright (C) 2012, 2015 Connor Olding
 
 Permission is hereby granted, free of charge, to any person
 obtaining a copy of this software and associated documentation
@@ -20,4 +20,3 @@ HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 OTHER DEALINGS IN THE SOFTWARE.
-

Makefile

@@ -1,19 +1,14 @@
 PROGRAM = crc32
 .PHONY: all clean install
-FILES = main.c args.c crc32.c
-
-CFLAGS += -Wall -Werror -ansi -pedantic
-LDFLAGS +=
-PREFIX ?= /usr/local
 
 all: $(PROGRAM)
 
-$(PROGRAM): $(FILES)
+$(PROGRAM): main.c
-	$(CC) -o $@ $(CFLAGS) $(LDFLAGS) $(FILES)
+	$(CC) -o $@ -Wall -Winline -std=c99 $(CFLAGS) $(LDFLAGS) $^
 
 clean:
 	-rm -f $(PROGRAM)
 
 install:
-	cp $(PROGRAM) $(PREFIX)/bin
+	install -m 0755 -d $(PREFIX)/bin
-
+	install -m 0755 $(PROGRAM) $(PREFIX)/bin

README.md

@@ -5,12 +5,6 @@ It computes [crc32s,][crc] and what of it?
 
 [crc]: http://en.wikipedia.org/wiki/Cyclic_redundancy_check
 
-Update
-------
-If portability isn't a concern; as in your compiler can build gnu11 code;
-I'd recommend you use the ["modern"](https://github.com/notwa/crc32/tree/modern) branch.
-The code is much cleaner and slightly faster.
-
 Usage
 ----
 ```
@@ -25,13 +19,7 @@ crc32 - a 32-bit cyclic rendundancy check calculator
   -x                NOT the output
   -r                reverse output's bits
 
-numbers <n> may be entered as hexadecimal or octal with prefixes
+numbers <n> may be in hexadecimal or octal using proper prefixes
 ```
 
-Notes
------
-
-*	Does not pad input.
-*	Big endian calculations are somewhat untested.
-
 ## [Smaller Still](https://gist.github.com/notwa/5689243)

args.c

@@ -1,17 +1,10 @@
-/* Copyright (C) 2012 Connor Olding
- *
- * This program is licensed under the terms of the MIT License, and
- * is distributed without any warranty.  You should have received a
- * copy of the license along with this program; see the file LICENSE.
- */
-
 #include <stddef.h>
-#include "args.h"
 
 static int argc, argi;
 static char **argv, *flag;
 
-static char *nextarg()
+static char *
+nextarg()
 {
 	char *temp = flag;
 	flag = NULL;
@@ -22,7 +15,8 @@ static char *nextarg()
 	return argv[argi];
 }
 
-void args_parse(int argc_, char **argv_,
+static void
+args_parse(int argc_, char **argv_,
     void flagfn(char, char*()), void plainfn(char*))
 {
 	argc = argc_;
@@ -54,4 +48,3 @@ void args_parse(int argc_, char **argv_,
 		if (plainfn)
 			plainfn(argv[argi]);
 }
-

args.h

@@ -1,10 +0,0 @@
-/* Copyright (C) 2012 Connor Olding
- *
- * This program is licensed under the terms of the MIT License, and
- * is distributed without any warranty.  You should have received a
- * copy of the license along with this program; see the file LICENSE.
- */
-
-void args_parse(int argc, char **argv,
-    void flagfn(char, char*()), void plainfn(char*));
-

crc32.c

@@ -1,18 +1,10 @@
-/* Copyright (C) 2012 Connor Olding
+enum { CRC_TABLE_SIZE = 0x100 };
- *
- * This program is licensed under the terms of the MIT License, and
- * is distributed without any warranty.  You should have received a
- * copy of the license along with this program; see the file LICENSE.
- */
 
-typedef unsigned long ulong;
+static inline uint32_t
-#include "crc32.h"
+crc_reflect(uint32_t input)
-
-ulong crc_reflect(ulong input)
 {
-	ulong reflected = 0;
+	uint32_t reflected = 0;
-	int i;
+	for (int i = 0; i < 32; i++) {
-	for (i = 0; i < 4 * 8; i++) {
 		reflected <<= 1;
 		reflected |= input & 1;
 		input >>= 1;
@@ -20,34 +12,56 @@ ulong crc_reflect(ulong input)
 	return reflected;
 }
 
-void crc_fill_table(ulong *table, int big, ulong polynomial)
+static inline void
+crc_be_fill_table(uint32_t *table, uint32_t polynomial)
 {
-	ulong lsb = (big) ? 1 << 31 : 1; /* least significant bit */
+	const uint32_t lsb = 1 << 31;
-	ulong poly = (big) ? polynomial : crc_reflect(polynomial);
+	uint32_t poly = polynomial;
-	int c, i;
 
-	for (c = 0; c < CRC_TABLE_SIZE; c++, table++) {
+	for (int c = 0; c < CRC_TABLE_SIZE; c++) {
-		*table = (big) ? c << 24 : c;
+		uint32_t v = c << 24;
-		for (i = 0; i < 8; i++) {
+		for (int i = 0; i < 8; i++) {
-			if (*table & lsb) {
+			if (v & lsb) {
-				*table = (big) ? *table << 1 : *table >> 1;
+				v <<= 1;
-				*table ^= poly;
+				v ^= poly;
 			} else {
-				*table = (big) ? *table << 1 : *table >> 1;
+				v <<= 1;
 			}
-			*table &= 0xFFFFFFFF;
 		}
+		*table++ = v;
 	}
 }
 
-void crc_be_cycle(ulong *table, ulong *remainder, char c)
+static inline void
+crc_le_fill_table(uint32_t *table, uint32_t polynomial)
 {
-	ulong byte = table[(((*remainder) >> 24) ^ c) & 0xff];
+	const uint32_t lsb = 1;
-	*remainder = (((*remainder) << 8) ^ byte) & 0xFFFFFFFF;
+	uint32_t poly = crc_reflect(polynomial);
+
+	for (int c = 0; c < CRC_TABLE_SIZE; c++) {
+		uint32_t v = c;
+		for (int i = 0; i < 8; i++) {
+			if (v & lsb) {
+				v >>= 1;
+				v ^= poly;
+			} else {
+				v >>= 1;
+			}
+		}
+		*table++ = v;
+	}
 }
 
-void crc_le_cycle(ulong *table, ulong *remainder, char c)
+static inline void
+crc_be_cycle(uint32_t *table, uint32_t *remainder, uint8_t c)
 {
-	ulong byte = table[((*remainder) ^ c) & 0xFF];
+	const uint8_t i = (*remainder >> 24) ^ c;
-	*remainder = ((*remainder) >> 8) ^ byte;
+	*remainder = (*remainder << 8) ^ table[i];
+}
+
+static inline void
+crc_le_cycle(uint32_t *table, uint32_t *remainder, uint8_t c)
+{
+	const uint8_t i = (*remainder & 0xFF) ^ c;
+	*remainder = (*remainder >> 8) ^ table[i];
 }

crc32.h

@@ -1,13 +0,0 @@
-/* Copyright (C) 2012 Connor Olding
- *
- * This program is licensed under the terms of the MIT License, and
- * is distributed without any warranty.  You should have received a
- * copy of the license along with this program; see the file LICENSE.
- */
-
-enum { CRC_TABLE_SIZE = 0x100 };
-
-void crc_fill_table(ulong *table, int big, ulong polynomial);
-void crc_be_cycle(ulong *table, ulong *remainder, char c);
-void crc_le_cycle(ulong *table, ulong *remainder, char c);
-ulong crc_reflect(ulong input);

main.c

@@ -1,45 +1,30 @@
-/* Copyright (C) 2012 Connor Olding
- *
- * This program is licensed under the terms of the MIT License, and
- * is distributed without any warranty.  You should have received a
- * copy of the license along with this program; see the file LICENSE.
- */
-
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdint.h>
 
-typedef unsigned long ulong;
+#include "crc32.c"
+#include "args.c"
 
-#include "crc32.h"
+typedef int bool;
-#include "args.h"
-
-#ifdef _MSC_VER
-	#define FREOPEN_BLANK ("")
-#else
-	#define FREOPEN_BLANK (NULL)
-#endif
 
 #ifndef BUFFER_SIZE
 #define BUFFER_SIZE 4096
 #endif
 char buff[BUFFER_SIZE];
 
-typedef struct string_node_s string_node;
+#define MAX_INPUTS 256
-struct string_node_s {
-	char *s;
-	string_node *next;
-};
 
-static string_node *input_node = NULL;
+static char *inputs[MAX_INPUTS];
+static int input_n = 0;
 
-static ulong starting = 0xFFFFFFFF;
+static uint32_t starting = 0xFFFFFFFF;
-static char big_endian = 0;
+static bool big_endian = 0;
-static ulong polynomial = 0x04C11DB7;
+static uint32_t polynomial = 0x04C11DB7;
-static char print_binary = 0;
+static bool print_binary = 0;
-static char xor_output = 1;
+static bool xor_output = 1;
-static char reflect_output = 0;
+static bool reflect_output = 0;
 
-static const char help1[] = "\
+static const char help[] = "\
 crc32 - a 32-bit cyclic rendundancy check calculator\n\
 \n\
   <files...>        open files as inputs\n\
@@ -51,12 +36,11 @@ crc32 - a 32-bit cyclic rendundancy check calculator\n\
   -x                NOT the output\n\
   -r                reverse output's bits\n\
 \n\
-";
+numbers <n> may be in hexadecimal or octal using proper prefixes\n\
-static const char help2[] = "\
-numbers <n> may be entered as hexadecimal or octal with prefixes\n\
 ";
 
-static char *check_next(char flag, char *next) {
+static char
+*check_next(char flag, char *next) {
 	if (!next) {
 		fprintf(stderr, "-%c requires another argument\n", flag);
 		exit(1);
@@ -64,58 +48,52 @@ static char *check_next(char flag, char *next) {
 	return next;
 }
 
-static void handle_flag(char flag, char *(*nextarg)())
+static void
+handle_flag(char flag, char *(*nextarg)())
 {
 	char *next;
 	switch (flag) {
-	case 'h':
+	case 'h': {
-		printf(help1);
+		printf(help);
-		printf(help2);
+	} exit(0);
-		exit(0);
+	case 'e': {
-	case 'e':
 		big_endian = 1;
-		return;
+	} break;
-	case 'b':
+	case 'b': {
 		print_binary = 1;
-		return;
+	} break;
-	case 'x':
+	case 'x': {
 		xor_output = 0;
-		return;
+	} break;
-	case 'r':
+	case 'r': {
 		reflect_output = 1;
-		return;
+	} break;
-	case 's':
+	case 's': {
 		next = check_next(flag, nextarg());
 		starting = strtoul(next, NULL, 0);
-		break;
+	} break;
-	case 'p':
+	case 'p': {
 		next = check_next(flag, nextarg());
 		polynomial = strtoul(next, NULL, 0);
-		break;
+	} break;
-	default:
+	default: {
 		fprintf(stderr, "Unknown flag: -%c\n", flag);
-		exit(1);
+	} exit(1);
 	}
 }
 
-static void add_input(char *arg)
+static void
+add_input(char *arg)
 {
-	static string_node *last = NULL;
+	if (input_n >= MAX_INPUTS) {
-	string_node *n = calloc(1, sizeof(string_node));
+		fprintf(stderr, "Too many inputs specified\n");
-	if (!n) {
-		fprintf(stderr, "calloc failed\n");
 		exit(1);
 	}
-
+	inputs[input_n++] = arg;
-	n->s = arg;
-	if (!input_node)
-		input_node = n;
-	else
-		last->next = n;
-	last = n;
 }
 
-static FILE *open_stream(char *filename)
+static FILE *
+open_stream(char *filename)
 {
 	FILE *stream = NULL;
 	stream = fopen(filename, "rb");
@@ -126,25 +104,38 @@ static FILE *open_stream(char *filename)
 	return stream;
 }
 
-
+static inline size_t
-static ulong cycle_file(FILE *stream)
+buff_read(FILE *stream)
 {
-	ulong remainder = starting;
+	size_t len = fread(buff, 1, BUFFER_SIZE, stream);
-	void (*cycle)(ulong*, ulong*, char) =
+	if (ferror(stream)) {
-	    (big_endian) ? crc_be_cycle : crc_le_cycle;
+		perror(NULL);
-	ulong table[CRC_TABLE_SIZE];
+		exit(1);
-	int i, len;
+	}
+	return len;
+}
 
-	crc_fill_table(table, big_endian, polynomial);
+static uint32_t
-	do {
+cycle_file(FILE *stream)
-		len = fread(buff, 1, BUFFER_SIZE, stream);
+{
-		if (ferror(stream)) {
+	uint32_t remainder = starting;
-			perror(NULL);
+	uint32_t table[CRC_TABLE_SIZE];
-			exit(1);
-		}
 
-		for (i = 0; i < len; i++)
+	if (big_endian)
-			cycle(table, &remainder, buff[i]);
+		crc_be_fill_table(table, polynomial);
+	else
+		crc_le_fill_table(table, polynomial);
+
+	// cast len to int to enable potential signedness optimizations.
+	// this is safe so long as BUFFER_SIZE can fit in an int.
+	if (big_endian) do {
+		int len = (int) buff_read(stream);
+		for (int i = 0; i < len; i++)
+			crc_be_cycle(table, &remainder, buff[i]);
+	} while (!feof(stream)); else do {
+		int len = (int) buff_read(stream);
+		for (int i = 0; i < len; i++)
+			crc_le_cycle(table, &remainder, buff[i]);
 	} while (!feof(stream));
 
 	if (xor_output)
@@ -154,7 +145,8 @@ static ulong cycle_file(FILE *stream)
 	return remainder;
 }
 
-static void print_crc(ulong remainder)
+static void
+print_crc(uint32_t remainder)
 {
 	if (print_binary)
 		fwrite(&remainder, sizeof(remainder), 1, stdout);
@@ -162,30 +154,19 @@ static void print_crc(ulong remainder)
 		printf("%08X\n", (int) remainder);
 }
 
-static void free_nodes(string_node *n)
+int
+main(int argc, char **argv)
 {
-	string_node *next;
-	while (n) {
-		next = n->next;
-		free(n);
-		n = next;
-	}
-}
-
-int main(int argc, char **argv)
-{
-	string_node *n;
 	args_parse(argc, argv, handle_flag, add_input);
 
-	if (!input_node) {
+	if (!input_n) {
-		freopen(FREOPEN_BLANK, "rb", stdin);
+		freopen(NULL, "rb", stdin);
 		print_crc(cycle_file(stdin));
 	}
-	for (n = input_node; n; n = n->next) {
+	for (int i = 0; i < input_n; i++) {
-		FILE *stream = open_stream(n->s);
+		FILE *stream = open_stream(inputs[i]);
 		print_crc(cycle_file(stream));
 		fclose(stream);
 	}
-	free_nodes(input_node);
 	return 0;
 }