refactor common parts into inc/ch375.h and add win9x, linux drivers

1 files changed, 61 insertions, 0 deletions

diff --git a/inc/scsi.h b/inc/scsi.h
new file mode 100644
index 0000000..a9d8b05
--- /dev/null
+++ b/inc/scsi.h
@@ -0,0 +1,61 @@
+#ifndef SCSICAM_H
+#define SCSICAM_H
+
+/** (from SCSICAM) converts a capacitity in sectors to CHS
+ *  keeps cylinders <= 1024 and sectors <= 62,
+ *  but may give very large head numbers, though. */
+static int setsize(unsigned long capacity, unsigned int *cyls, unsigned int *hds, unsigned int *secs)
+{
+	unsigned int rv = 0;
+	unsigned long heads, sectors, cylinders, temp;
+
+	cylinders = 1024L;	/* Set number of cylinders to max */
+	sectors = 62L;		/* Maximize sectors per track */
+
+	temp = cylinders * sectors;	/* Compute divisor for heads */
+	heads = capacity / temp;	/* Compute value for number of heads */
+	if (capacity % temp) {	/* If no remainder, done! */
+		heads++;	/* Else, increment number of heads */
+		temp = cylinders * heads;	/* Compute divisor for sectors */
+		sectors = capacity / temp;	/* Compute value for sectors per
+						   track */
+		if (capacity % temp) {	/* If no remainder, done! */
+			sectors++;	/* Else, increment number of sectors */
+			temp = heads * sectors;		/* Compute divisor for cylinders */
+			cylinders = capacity / temp;	/* Compute number of cylinders */
+		}
+	}
+	if (cylinders == 0)
+		rv = (unsigned) -1;	/* Give error if 0 cylinders */
+
+	*cyls = (unsigned int) cylinders;	/* Stuff return values */
+	*secs = (unsigned int) sectors;
+	*hds = (unsigned int) heads;
+	return (rv);
+}
+
+static void guess_geometry(uint32_t num_sectors, unsigned int *cyls, unsigned int *hds, unsigned int *secs)
+{
+	unsigned int cylinders, heads, sectors;
+	// First try to use SCSI CAM approach
+	if (setsize(num_sectors, &cylinders, &heads, &sectors) != 0
+	        || cylinders > 1024 || heads  > 255 || sectors > 63) {
+		// Didn't work. So now we just use max heads and sectors but a crazy number of cyls
+		if (num_sectors <= 64 * 32 * 65534) {
+			// This follows the same behavior as Linux,
+			// which uses smaller values for heads/sects as long as cyls fits < 65535
+			heads = 64;
+			sectors = 32;
+		} else {
+			heads = 255;
+			sectors = 63;
+		}
+		cylinders = num_sectors / (heads * sectors);
+	}
+
+	*cyls = cylinders;
+	*hds = heads;
+	*secs = sectors;
+}
+
+#endif // SCSICAM_H