1 files changed, 72 insertions, 0 deletions
diff --git a/device.c b/device.c
new file mode 100644
index 0000000..4bbf7b8
--- /dev/null
+++ b/device.c
@@ -0,0 +1,72 @@
+/*  Copyright 2021 Alain Knaff.
+ *  This file is part of mtools.
+ *
+ *  Mtools is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Mtools is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with Mtools.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "sysincludes.h"
+#include "llong.h"
+#include "device.h"
+
+int check_if_sectors_fit(uint32_t tot_sectors,
+			 mt_off_t maxBytes,
+			 uint32_t sectorSize,
+			 char *errmsg)
+{
+	if(!maxBytes)
+		return 0; /* Maxbytes = 0 => no checking */
+	if(tot_sectors > (smt_off_t) maxBytes / (smt_off_t) sectorSize) {
+		sprintf(errmsg,
+			"%d sectors too large for this platform\n",
+			tot_sectors);
+		return -1;
+	}
+	return 0;
+}
+
+/*
+ * Calculate number of total sectors on device if needed, and check that
+ * they fit into 
+ */
+int chs_to_totsectors(struct device *dev, char *errmsg)
+{
+	uint32_t sect_per_track, tot_sectors;
+	
+	if(dev->tot_sectors)
+		return 0;
+		
+	if(!dev->heads || !dev->sectors || !dev->tracks)
+		return 0; /* not fully specified => we cannot do
+			     anything anyways */
+		
+	/* Cannot overflow as both dev->heads and dev->sectors are 16
+	 * bit quantities, whose product will be put into a 32 bit
+	 * field */
+	sect_per_track = dev->heads * dev->sectors;
+
+	if(dev->tracks > UINT32_MAX / sect_per_track) {
+		/* Would not fit in 32 bits */
+
+		if(errmsg)
+			sprintf(errmsg,
+				"Number of sectors larger than 2^32\n");
+		return -1;
+	}
+
+	tot_sectors = dev->tracks * sect_per_track;
+	if(tot_sectors > dev->hidden % sect_per_track)
+		tot_sectors -= dev->hidden % sect_per_track;
+	dev->tot_sectors = tot_sectors;
+	return 0;
+}