added crc32

sys/src/cmd/crc32.c

@@ -0,0 +1,99 @@
+#include <u.h>
+#include <libc.h>
+#include <libsec.h>
+
+u32int table[256];
+u32int xor = -1, init, poly = 0xedb88320;
+char *error;
+
+static void
+dotable(void)
+{
+	u32int c;
+	int n, k;
+
+	for(n = 0; n < 256; n++){
+		c = n;
+		for(k = 0; k < 8; k++)
+			if((c & 1) != 0)
+				c = poly ^ c >> 1;
+			else
+				c >>= 1;
+		table[n] = c;
+	}
+}
+
+static u32int
+calc(u32int init, uchar *buf, ulong len)
+{
+	u32int c;
+	
+	c = init;
+	while(len-- != 0)
+		c = table[(*buf++ ^ c) & 0xff] ^ c >> 8;
+	return c;
+}
+
+static void
+sum(int fd, char *name)
+{
+	int n;
+	uchar buf[8192];
+	u32int crc;
+
+	crc = init ^ xor;
+	while((n = read(fd, buf, sizeof buf)) > 0)
+		crc = calc(crc, buf, n);
+	if(n < 0){
+		fprint(2, "reading %s: %r\n", name ? name : "stdin");
+		error = "read";
+		return;
+	}
+	crc ^= xor;
+	if(name == nil)
+		print("%ux\n", crc);
+	else
+		print("%ux\t%s\n", crc, name);
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s [-x xorval] [-i initial] [-p poly] [file...]\n", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	int i, fd;
+
+	ARGBEGIN{
+	case 'x':
+		xor = strtol(EARGF(usage()), 0, 0);
+		break;
+	case 'i':
+		init = strtol(EARGF(usage()), 0, 0);
+		break;
+	case 'p':
+		poly = strtol(EARGF(usage()), 0, 0);
+		break;
+	default:
+		usage();
+	}ARGEND
+
+	dotable();
+	if(argc == 0)
+		sum(0, nil);
+	else for(i = 0; i < argc; i++){
+		fd = open(argv[i], OREAD);
+		if(fd < 0){
+			fprint(2, "crc32: can't open %s: %r\n", argv[i]);
+			error = "open";
+			continue;
+		}
+		sum(fd, argv[i]);
+		close(fd);
+	}
+	exits(error);
+}

sys/src/games/gba/gba.c

@@ -198,8 +198,8 @@ loadrom(char *file)
 	if(fd < 0)
 		sysfatal("open: %r");
 	sz = seek(fd, 0, 2);
-	if(sz <= 0 || sz >= 32*1024*1024)
+	if(sz <= 0 || sz > 32*1024*1024)
-		sysfatal("nope.jpg");
+		sysfatal("invalid file size");
 	seek(fd, 0, 0);
 	nrom = sz;
 	rom = emalloc(nrom);

sys/src/games/snes/snes.c

@@ -95,6 +95,7 @@ loadbat(char *file)
 	char *s;
 
 	if(battery && nsram != 0){
+		buf[sizeof buf - 1] = 0;
 		strncpy(buf, file, sizeof buf - 5);
 		s = buf + strlen(buf) - 4;
 		if(s < buf || strcmp(s, ".smc") != 0)