Synnefo » snf-image

    def lba2chs(self, lba, hpc=None, spt=None):

        """Return the CHS address for a given LBA address"""

        # NetBSD uses LBA-Assisted translation. The sectors per track (spt)

        # value is always 63 and the heads per cylinder (hpc) value depends on

        # the size of the disk

        disk_size = self.field['secperunit']

        # Maximum disk size that can be addressed is 1024 * HPC* SPT

        spt = 63

        for hpc in 16, 32, 64, 128, 255:

            if disk_size <= 1024 * hpc * spt:

                break

        chs = super(BSDDisklabel, self).lba2chs(lba, hpc, spt)

        if chs[0] > 1023:  # Cylinders overflowed

            assert hpc == 255  # Cylinders may overflow only for large disks

            return (1023, chs[1], chs[2])

        return chs